M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: 91 318is on May 25, 2009, 01:44:20 PM
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First off, I've searched on a few boards to see if this is a common problem, everyone seems to say it's the vacuum hoses under the intake. I took care of that last year and replace every gasket that I took off, still have this problem. When you first start it up, for some reason, it idles at about 600, and almost everytime, it will stumble, sometimes it will catch itself and come back up, sometimes it stalls. I checked the plugs, change the coolant sensor for the ECU, and changed all the gaskets on the intake and bypassed all the vacuum hoses.
Anyone have any ideas? I'm thinking it might be the AFM, anyway I can confirm this? I would hate to drop $250+ for a new AFM and it not be the problem.
Thanks
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You've really done a lot of work so far, I'd check all the same stuff in the same order. Have you tested the fuel pressure regulator or pump?
I'd try to adjust the AFM before replacing it. I don't think they can be easily tested.
There's an idle control screw in there, but I've never messed with it.
There is a temp sensor too, never messed with that either.
There is also a gear wheel inside that puts tension on the flap door spring. It's easily adjustable. I HAVE messed with that. It helps a little with some idle and throttle response issues.
Get a knife, carefully cut the silicone all the way around the little black cover on top of the AFM, and paint a location mark on the gear and housing. Then you can return to stock if necessary.
Then change the gear setting by a tooth or two. Test and repeat. If I recall correctly, turning the toothed wheel clockwise tensions the spring (leaner), CCW loosens it (richer).
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Only does this on cold starts? Not warm starts?
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I have done that myself.
So 91 318IS, you can adjust the spring tension to accomodate the lack of idle. I would suggest leaning the motor out, loosen the tension on the AFM spring. This kinda guarentee's that the motor wont start. Then you work your way back up. But too much tension and of course it wont run right.
When I first got my 91 318is (Natasha) back in 97 she had the same issue. The first thing I checked was all the hoses.
Then for S n G's I changed the O2 sensor. Good luck.
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You've really done a lot of work so far, I'd check all the same stuff in the same order. Have you tested the fuel pressure regulator or pump?
I'd try to adjust the AFM before replacing it. I don't think they can be easily tested.
There's an idle control screw in there, but I've never messed with it.
There is a temp sensor too, never messed with that either.
There is also a gear wheel inside that puts tension on the flap door spring. It's easily adjustable. I HAVE messed with that. It helps a little with some idle and throttle response issues.
Get a knife, carefully cut the silicone all the way around the little black cover on top of the AFM, and paint a location mark on the gear and housing. Then you can return to stock if necessary.
Then change the gear setting by a tooth or two. Test and repeat. If I recall correctly, turning the toothed wheel clockwise tensions the spring (leaner), CCW loosens it (richer).
Haven't checked the pressure yet, I will though. I actually did take the top off the AFM and wanted to look inside at the potentiometer, I cleaned it with contact cleaner, but that didn't help. I will take the top back off and try to adjust it.
Here's another question, is it normal for the idle to rise as the engine get's warmer? For every other car I've owned, it was always backwards.
Only does this on cold starts? Not warm starts?
You know, now that I think about it, it does it on warm start up sometimes too.
Sorry, it's been 9 months since I've driven it (got back from paint) so I forgot all the little quarks of her.
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Here's another question, is it normal for the idle to rise as the engine get's warmer? For every other car I've owned, it was always backwards.
It's normal for the computer (DME) to raise idle on cold starts, but the car will idle very badly if the DME doesn't 'see' that the engine is cold. The DME uses the coolant and intake air temp sensors to determine temperature.
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It's normal for the computer (DME) to raise idle on cold starts, but the car will idle very badly if the DME doesn't 'see' that the engine is cold. The DME uses the coolant and intake air temp sensors to determine temperature.
Right, so on a cold start, it should idle higher then on a warm start? Mine is backwards, it idles at about 600 on a cold start and when it's fully warm, it's about at 1,000.
Also, where is the fuel pressure test port? I figured it would be somewhere on the rail but I didn't see it, am I not looking hard enough?
Thanks again for all the help guys, really want to get this bug out.
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Right, so on a cold start, it should idle higher then on a warm start? Mine is backwards, it idles at about 600 on a cold start and when it's fully warm, it's about at 1,000.
Also, where is the fuel pressure test port? I figured it would be somewhere on the rail but I didn't see it, am I not looking hard enough?
Thanks again for all the help guys, really want to get this bug out.
I'd guess that the car isn't getting the right signal to know it's cold, so it's not rich enough and it never gets to high idle... I think the fuel pressure valve is only on M44 fuel rails, it's not on our M42s. Not sure...anyone else know?
Did you do the stomp test to see what the computer thinks is wrong? That was where I started. I hate to tell you this, but I had to eliminate almost every major system before I found out what was wrong:
1. Stomp test told me code 1215, AFM problem.
2. Fuel pump test gave me acceptable flow, pressure was a little low.
3. Spark plugs were oily, but gave a good spark anyway.
4. After working my way around the sensors, I found that the AFM plug was waterlogged and the CPS was well oiled from my weeping main seal.
5. Car started after I cleared up those two problems. DME still tells me code 1215 - AFM is bad. I'll be looking at that again and posting my findings...
The lesson I learned (other than that so many systems are close to total failure), was that I had to single out each component for testing. I wasted hours guessing before I started eliminating the good sensors one at a time. I can't afford to replace every sensor...for that price I could be probably be leasing a new BMW.
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I'd guess that the car isn't getting the right signal to know it's cold, so it's not rich enough and it never gets to high idle... I think the fuel pressure valve is only on M44 fuel rails, it's not on our M42s. Not sure...anyone else know?
Did you do the stomp test to see what the computer thinks is wrong? That was where I started. I hate to tell you this, but I had to eliminate almost every major system before I found out what was wrong:
1. Stomp test told me code 1215, AFM problem.
2. Fuel pump test gave me acceptable flow, pressure was a little low.
3. Spark plugs were oily, but gave a good spark anyway.
4. After working my way around the sensors, I found that the AFM plug was waterlogged and the CPS was well oiled from my weeping main seal.
5. Car started after I cleared up those two problems. DME still tells me code 1215 - AFM is bad. I'll be looking at that again and posting my findings...
The lesson I learned (other than that so many systems are close to total failure), was that I had to single out each component for testing. I wasted hours guessing before I started eliminating the good sensors one at a time. I can't afford to replace every sensor...for that price I could be probably be leasing a new BMW.
Thanks for all the good tips man, I will definitely try some of this out. I've actually never heard of the stomp test, but I'll look into it. I've worked on american cars my whole life, so german cars are a new thing for me.
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bump on the pressure test port, still haven't found it.
Also, been looking and haven't found any info yet but what exactly is the "stomp" test?
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Get in the car and turn key to position 2... stomp (literally) the pedal 5 times in rapid succession. Then the car should start blinking the check light at you. It will do a code so count how many short blinks and long blinks there are. Then return with answer.
Also try the "Did we ever figure out that warm start issue" thread. Simple to check one wire. Did the trick for a bunch of us. If the car has always done this then it might be that wire. If the car developed this problem then it's not likely.
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Get in the car and turn key to position 2... stomp (literally) the pedal 5 times in rapid succession. Then the car should start blinking the check light at you. It will do a code so count how many short blinks and long blinks there are. Then return with answer.
Also try the "Did we ever figure out that warm start issue" thread. Simple to check one wire. Did the trick for a bunch of us. If the car has always done this then it might be that wire. If the car developed this problem then it's not likely.
Thanks! Ever since I've driven the car, it's done this. I'll go out and try check it and let you know what happens.
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Check the wire, unfortunely the wire wasn't the problem.
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I was trying to count service engine light flashes and I confused myself so I didn't get it. How many numbers are in the code so I know how many I should look for?
I guess if you don't catch the code the first time, you can't get it to repeat? I tried to get it to repeat a few times and was unsuccessful.
Thanks
EDIT: Nevermind about the codes, realized it's 4.
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Was the wire plugged in or unplugged?
Did you manage to get the code? I should keep repeating the series of 4 numbers over and over separated by one long period (4 or 5 seconds) of no light flashing.
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Was the wire plugged in or unplugged?
Did you manage to get the code? I should keep repeating the series of 4 numbers over and over separated by one long period (4 or 5 seconds) of no light flashing.
The wire was unplugged.
Hold on, now I'm confused, am I counting the flashing of the light? Or the pauses between the flashes? I've read codes by the flashing SES light, and they were counted by the number of times the SES light flashes.
Hopefully I'm not confusing you.
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When you do the stomp test, are you resetting the computer? The reason I say this is because since I did the test the first time, I can't get the code to flash again.
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Sorry...I should have been more specific. All Bosch cars have this feature (with different tricks to access it), some American cars have it too. It's the way things were before OBDII and code readers.
You're definitely counting the blinks. The pauses are important too because they tell you if you're between codes.
The codes are a little hard to read until you get some practice. I take a tablet and jot them down because I forget them as they blink out. They're all four digit codes, and when you get the stomping just right it'll start blinking. They look random but they aren't...and you have to pay close attention. If you miss one, that's OK, they'll keep repeating as long as you keep the key in position 2. Here's a list of the codes:
http://e30world.com/fuel/BMW-E30-DME-Motronic-fault-codes
The light will start with a long (4-5 seconds) blink on. Then a long pause (4-5 seconds again) and it'll start into the codes it has stored. Each code is four numbers, it'll blink them out quickly with shorter pauses between the four digits.
When it's all done, it'll give another long blink on and start all over again.
For example, when I tried mine I saw this pattern with the check engine light:
Long flash (lets you know that it's starting the sequence)
long pause
one quick blink, short pause
four quick blinks & a short pause
four quick blinks & a short pause
four quick blinks & a long pause...then it starts all over again with a long blink and repeats until you turn off the ignition or break the instrument cluster out of sheer frustration :rolleyes:
It's a code 1444, 'No Codes'. I'm all clear...no troubles at all :D You might get that even if the car isn't starting...it's frustrating at times :mad:. I did have a code 1215 (AFM) when I bought the car, but it ended up being a vacuum leak. The codes are just clues, don't replace things willy-nilly when the ECU/DME/computer starts telling you they're bad.
Oh yeah...one more thing...if you have multiple codes it'll do them in sequence. Even if you mess one up, you can catch the others and wait for it to repeat. Sorry for the short novel here, but it's hard to explain it...but when you understand it you can impress your friends with your psychic mechanic powers.
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Sorry...I should have been more specific. All Bosch cars have this feature (with different tricks to access it), some American cars have it too. It's the way things were before OBDII and code readers.
You're definitely counting the blinks. The pauses are important too because they tell you if you're between codes.
The codes are a little hard to read until you get some practice. I take a tablet and jot them down because I forget them as they blink out. They're all four digit codes, and when you get the stomping just right it'll start blinking. They look random but they aren't...and you have to pay close attention. If you miss one, that's OK, they'll keep repeating as long as you keep the key in position 2. Here's a list of the codes:
http://e30world.com/fuel/BMW-E30-DME-Motronic-fault-codes
The light will start with a long (4-5 seconds) blink on. Then a long pause (4-5 seconds again) and it'll start into the codes it has stored. Each code is four numbers, it'll blink them out quickly with shorter pauses between the four digits.
When it's all done, it'll give another long blink on and start all over again.
For example, when I tried mine I saw this pattern with the check engine light:
Long flash (lets you know that it's starting the sequence)
long pause
one quick blink, short pause
four quick blinks & a short pause
four quick blinks & a short pause
four quick blinks & a long pause...then it starts all over again with a long blink and repeats until you turn off the ignition or break the instrument cluster out of sheer frustration :rolleyes:
It's a code 1444, 'No Codes'. I'm all clear...no troubles at all :D You might get that even if the car isn't starting...it's frustrating at times :mad:. I did have a code 1215 (AFM) when I bought the car, but it ended up being a vacuum leak. The codes are just clues, don't replace things willy-nilly when the ECU/DME/computer starts telling you they're bad.
Oh yeah...one more thing...if you have multiple codes it'll do them in sequence. Even if you mess one up, you can catch the others and wait for it to repeat. Sorry for the short novel here, but it's hard to explain it...but when you understand it you can impress your friends with your psychic mechanic powers.
Thanks much. So even if I don't have any codes, it will still flash 1444? Because I can't get it to flash anything. The first time I tried it, I got it working, but since then, nothing.
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I sometimes have a lot of trouble getting it to work too. It'll always flash something, code 1444 even if nothing else.
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Ok, just got back in, slowed my stomps down a little and got it to working.
Flashed code 1444 so I'm guessing it's nothing DME related.
Maybe the ICV?
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Yeah, that's what I'm thinking. You already did the vacuum lines. Unless it's some odd fuel pump/pressure issue...they're undoubtedly the three biggest trouble spots on these cars.
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Yeah, that's what I'm thinking. You already did the vacuum lines. Unless it's some odd fuel pump/pressure issue...they're undoubtedly the three biggest trouble spots on these cars.
I still haven't found the test port to check the pressure, any idea where it's at?
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I don't think there is a port on the e30...if one was added later on my 8/90 was too early in the production run. Wasn't that added in the e36? Might be M44 only.
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I don't think there is a port on the e30...if one was added later on my 8/90 was too early in the production run. Wasn't that added in the e36? Might be M44 only.
Thanks, found my buddy's bentley and went through that. Turns out there isn't a test port, but you have to T in between the regulator and the fuel rail.
Also kept the bentley so I plan on troubleshooting and will update as soon as I find something.
Thanks again for ALL the help!
EDIT: Bentley manual doesn't have anything for the M42, would like to check fuel pressure and rail pressure, but don't have any specs or procedure. CRAP
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http://media.savarturbo.se/~mattias/...-manual-v7.pdf
And you'll need a copy of the E36 Bentley for engine stuff.
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http://media.savarturbo.se/~mattias/...-manual-v7.pdf
And you'll need a copy of the E36 Bentley for engine stuff.
page doesn't work:(
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I just found this link for the E36 Bentley...
http://www.maxbimmer.com/forums/showthread.php?p=1278645
Same 750 pages, but half the size? You'll need 7-zip or WinRAR to extract it. I'd also recommend Foxit Reader instead of the bloated Adobe Reader. SO much faster to open big PDFs.
Of course I already own the Bentley, but it's nice to have an electronic backup.
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So I checked the ICV today, was 8.5 ohms when it was cold, bentley calls for 40 ohms, but I checked another guys 318 ICV and it read the same thing, not sure about that. I also found out another thing, when I turn the ac on, the idle drops down to 750 (where it's suppose to be), as soon as I turn the ac off, it shoots back up to 1100, tell you anything?
My next step is checking the TPS and possibly replacing the 02 sensor. Also need to check the fuel pressure and regulator, still working on finding T fittings and such.
Unless anyone else has suggestions?
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page doesn't work:(
I see that. It worked when I tried from the thread in the M42 Reference section of the FAQ/Reference forum, but not from the direct link I provided you.:confused:
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I see that. It worked when I tried from the thread in the M42 Reference section of the FAQ/Reference forum, but not from the direct link I provided you.:confused:
no worries, just found it a copy of it.
Anyone have ideas yet?
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The fuel pressure should be about 40 psi. If its within 10 psi of that, you're Ok. (Or maybe not OK, because the problem is somewhere else.)
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thanks for this post. I had a problem like this in subzero temps in the winter. I never did figure out the source of the problem but figured it was due to extreme cold. I guess it could happen at any temp.
any updates?
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I had this same problem, engine starts up fine then bogs down after idling for a few seconds and it doesn't help if you give it gas. Only does it on really cold days - no vacuum leaks.
Anyway its likely the AFM. Don't bother with a new one - they are crazy expensive. Find someone on craigslist parting out an E36 with an M42 in it, or go to a junkyard. The AFM in the m42 - E36 is a different part # but it still works - mine runs even smoother. Anyway - shouldn't be more than $25-$40.
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If it's the AFM, take it apart and tune it a little. They're simple and not too hard to fix. Getting the mixture just right needs a WBO2 or exhaust gas analyzer though. I'll post some pics when I do mine.
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Hey guys, here's my update.........
I also found that the stumbling problem is more pronounced when the A/C is on, it will buck even more and harder then with the A/C off.
A guy at work has been helping me, he's been into europeans for a while so he has a better idea about bosch style systems. Anywho, I unplugged the o2 sensor and drove it for about a day to see how it would. By doing this, the car stays in open loop I think. Anywho, I didn't stumble, even with the A/C on, so he was thinking it was the 02 sensor. Changed that today, unhooked the battery to reset the DME and that didn't fix it. He also has an E30 318, so we swapped out his AFM to see if that would fix it and that didn't do anything either.
I also found that if I just stomp the gas at idle, it will stumble really hard, and continue to stumble almost to 5k, then will smooth out. My buddy was telling me it sounded like it was backfiring into the intake. The ICV shouldn't affect anything other then idle qualities correct?
Any ideas from that?
I hate to just throw parts at it, I just don't have the money for that. If I have to, I guess I will.
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So the O2 sensor cleared the problem up - I think you're onto something with the open loop. I also think that your 5k test puts the car in open loop. Most cars at wide-open throttle will go open loop, might be the same case for high RPMs. Might be a timing or fuel issue in closed loop then. Some sensor is telling the computer the wrong data, and the computer is just doing what it's programmed to do. Garbage In Garbage Out.
Something is keeping the car do high idle. A cold start should run up to 1200+rpm for a little while, and the car should also raise idle when A/C is on to compensate for the compressor drag. I thought it was programmed into the chip on Bosch Motronic systems. My old CIS system had relays to raise idle, but I'm sure they're now part of the engine management system.
I know I'm getting into really unusual causes, but maybe run some continuity tests on wires? Likely culprits are the temp sensor in the AFM, the AFM harness, coolant temp sensor on the block and that wiring. They all signal for a higher idle. That might explain why swapping parts didn't fix the problem. Don't just replace parts...test everything. It'll run so well that you'll be glad you did!
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So the O2 sensor cleared the problem up - I think you're onto something with the open loop. I also think that your 5k test puts the car in open loop. Most cars at wide-open throttle will go open loop, might be the same case for high RPMs. Might be a timing or fuel issue in closed loop then. Some sensor is telling the computer the wrong data, and the computer is just doing what it's programmed to do. Garbage In Garbage Out.
Something is keeping the car do high idle. A cold start should run up to 1200+rpm for a little while, and the car should also raise idle when A/C is on to compensate for the compressor drag. I thought it was programmed into the chip on Bosch Motronic systems. My old CIS system had relays to raise idle, but I'm sure they're now part of the engine management system.
I know I'm getting into really unusual causes, but maybe run some continuity tests on wires? Likely culprits are the temp sensor in the AFM, the AFM harness, coolant temp sensor on the block and that wiring. They all signal for a higher idle. That might explain why swapping parts didn't fix the problem. Don't just replace parts...test everything. It'll run so well that you'll be glad you did!
No the new o2 sensor DID NOT fix it. But before I changed it, I unplugged the o2 sensor and drove around for a day or so with it unplugged. Apparently from what my buddy told me, unplugging the o2 and driving put the car into open loop. So when it was open loop I wasn't having any problems driving. I didn't have the stumble or nothing like that, but the idle was still high.
My guy thinks it may be a "false" air leak, meaning there's a leak after the AFM on the engine. I personally don't think it is because as I stated, the problem seems to go away when I'm running the car with the o2 unplugged. I'm not sure it runs better in OPEN loop, because it stumbles when it's cold too.
Here's a list of what I've replaced/swapped for testing
~New temp sensor for the DME
~New o2 sensor
~heater plate delete on intake, removed all vacuum hoses
~New upper and lower intake gaskets, new throttle body gasket
~cleaned ICV 2 seperate times
~Swapped AFM
Hope that help anyone.
I gotta figure this out, it's killing me!
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No the new o2 sensor DID NOT fix it. But before I changed it, I unplugged the o2 sensor and drove around for a day or so with it unplugged. Apparently from what my buddy told me, unplugging the o2 and driving put the car into open loop. So when it was open loop I wasn't having any problems driving. I didn't have the stumble or nothing like that, but the idle was still high.
That's not what I was trying to get at. The new O2 sensor didn't fix the problem, but you used it to force open loop. I'm saying that when the car is in closed loop there is a bad sensor reading. When you plugged the sensor back in, you've eliminated it as a problem AND you're closer to the root of the problem.
My guy thinks it may be a "false" air leak, meaning there's a leak after the AFM on the engine. I personally don't think it is because as I stated, the problem seems to go away when I'm running the car with the o2 unplugged. I'm not sure it runs better in OPEN loop, because it stumbles when it's cold too.
I agree with you. I think it's a bad sensor, not a vacuum leak. Mine always stumbles when it's cold too, but only if it's ice cold and only for a minute maybe. I'm figuring your problem is a bad wire or harness connection, or even possibly a bad ECU. If your sensors & wiring keep testing out OK, maybe it's time to consider swapping them? BlackMagic has an ECU for sale here for $50 shipped:
http://www.m42club.com/forums/showthread.php?t=8837
If it's not the ECU I'm sure you could get your $50 back out of it.
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That's not what I was trying to get at. The new O2 sensor didn't fix the problem, but you used it to force open loop. I'm saying that when the car is in closed loop there is a bad sensor reading. When you plugged the sensor back in, you've eliminated it as a problem AND you're closer to the root of the problem.
I agree with you. I think it's a bad sensor, not a vacuum leak. Mine always stumbles when it's cold too, but only if it's ice cold and only for a minute maybe. I'm figuring your problem is a bad wire or harness connection, or even possibly a bad ECU. If your sensors & wiring keep testing out OK, maybe it's time to consider swapping them? BlackMagic has an ECU for sale here for $50 shipped:
http://www.m42club.com/forums/showthread.php?t=8837
If it's not the ECU I'm sure you could get your $50 back out of it.
Oh ok, I understand you now, sorry. Yeah now I just gotta figure out where the problem is. Also, I swapped out my ICV with the one the guy had at work, didn't seem to fix the problem. It seems to idle a little better at cold idle, but still idles high when warm.
Looks like I'll just dig into it in the next few days and see what I'll find.
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Oh another thing I was thinking about, could someone have tampered with my idle screw and that's causing the high idle? I swapped out the ICV from another E30 that worked on his and it's doing the EXACT same thing.
I also think the 02 sensor may have fixed the stumbling problem, is hasn't done it to me since I changed it, so hopefully that's fixed.
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bump, anyone have any input on the idle screw issue?
I actually adjusted the idle down the recommended idle (850) and seems to run better, except when I turn the A/C on, it stumbles down to about 500 for a few seconds and then comes back up to 850. Is this because I tampered with the idle screw?
Also, the car stumbled on me last night so I guess the 02 sensor didn't do the trick. Gonna dig into it some more this weekend I guess and start checking.
Thanks
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I was thinking about this a while...seems like you're getting closer...I'd be tempted to pick up a cheap $30 vacuum gauge, put it in the car somewhere and see what the engine is actually doing. I'd probably tee it off the FPR hose.
I'd adjust the idle control screw back up to a higher idle...you'll still have the stumble, but it won't go so low and stall the car.
Unfortunately I don't have an hard data on what you should be seeing, but I've run these on older cars to troubleshoot carbs (I know, I'm old...please hold off on the sarcasm...)
You'd get two benefits from this...first, you can 'see' what the engine is really doing when it's stumbling, and you can use it to improve your gas mileage. It works a little like the mileage meter on the dash but without the real-time calculation for approx MPG.
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I was thinking about this a while...seems like you're getting closer...I'd be tempted to pick up a cheap $30 vacuum gauge, put it in the car somewhere and see what the engine is actually doing. I'd probably tee it off the FPR hose.
I'd adjust the idle control screw back up to a higher idle...you'll still have the stumble, but it won't go so low and stall the car.
Unfortunately I don't have an hard data on what you should be seeing, but I've run these on older cars to troubleshoot carbs (I know, I'm old...please hold off on the sarcasm...)
You'd get two benefits from this...first, you can 'see' what the engine is really doing when it's stumbling, and you can use it to improve your gas mileage. It works a little like the mileage meter on the dash but without the real-time calculation for approx MPG.
And by reading the vacuum, I guess that would tell me if I have a leak somewhere? It's just hard for me because I understand troubleshooting and where to start, but I don't have any specs on anything or the "proper" test equipment. What should the vacuum be at idle?
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I don't think there is any hard and fast number for what a perfect idle is. When I'm looking at a compression gauge, temperature indicator or vacuum gauge I'm just looking for consistency. Any aberrations get my attention. I'm told about 20 inches is a healthy number.
An easy way to find vac leaks is to start the engine and spray a little carb cleaner around the hoses. If the engine idle smooths out, you're closing up the leak with the cleaner & you've found it. You can't test things like the brake booster or valve seals this way, but it's pretty simple.
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I don't think there is any hard and fast number for what a perfect idle is. When I'm looking at a compression gauge, temperature indicator or vacuum gauge I'm just looking for consistency. Any aberrations get my attention. I'm told about 20 inches is a healthy number.
An easy way to find vac leaks is to start the engine and spray a little carb cleaner around the hoses. If the engine idle smooths out, you're closing up the leak with the cleaner & you've found it. You can't test things like the brake booster or valve seals this way, but it's pretty simple.
Yeah, I did that when I first got the car and never could find anything. I sprayed so much the engine looked like new when I was done!
Anywho, I'll continue to slowly chip away at it, although it's getting frustrating, hopefully I'll find the culprit.
Oh and BTW, changed the plugs out today too, old ones look ok, but were worn down a little too much.
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Yeah, I did that when I first got the car and never could find anything. I sprayed so much the engine looked like new when I was done!
I might do that myself, the power steering is slowly mucking up my clean engine. That and a few seals, timing case gaskets, etc. etc...these cars are never done...:mad: But they're so much fun:D
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Here's another update
I hooked up my fuel pressure gauge inline with the feed line into the engine. I'll just make a list of what I did and the pressures I got.
Return line capped, fuel relay jumped with engine off - 71 psi
cold idle at 850, regulator vacuum line connected - 40 psi
cold idle at 850, regulator vacuum line disconnected and plugged - 49 psi
I also let it warm up to NEAR operating temps, pressure dropped a tad to 38-39 psi. I also held the RPM's at 3k and at first the psi went to about 50 something, then came back down about 40 psi. Stomped on the gas from idle and the car stumbled a few times like it's been, pressure seemed to fluctuate a little on the pressure gauge, but didn't drop significantly.
One other thing I heard was what sounded like the ignition arching near the coils/plugs and the RPM would drop, say maybe 50 rpm, nothing major, but you could definitely hear the RPM's flucuate. The arching didn't happen a lot, just every once in a while.
This info help anyone?
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bump, anyone?
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Swapped out the DME today with another guys at work, DME is for a 91 318is. Stumbled on me again coming home.
I give up:(
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Here's a thread I posted about using a vacuum gauge:
http://www.m42club.com/forums/showthread.php?t=7234
I agree with Dave about the usefulness of a vacuum gauge for troubleshooting. I've found most M42/M44 motors run about 17-18 hg at idle.
You can even put together a homemade vacuum gauge for just a few dollars.
http://www.komar.org/faq/manometer/
http://www.audiworld.com/tech/eng116.shtml
http://www.powerchutes.com/manometer.asp
(Disclaimer: I neither endorse or oppose the contents included in provided links)
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Here's a thread I posted about using a vacuum gauge:
http://www.m42club.com/forums/showthread.php?t=7234
I agree with Dave about the usefulness of a vacuum gauge for troubleshooting. I've found most M42/M44 motors run about 17-18 hg at idle.
You can even put together a homemade vacuum gauge for just a few dollars.
http://www.komar.org/faq/manometer/
http://www.audiworld.com/tech/eng116.shtml
http://www.powerchutes.com/manometer.asp
(Disclaimer: I neither endorse or oppose the contents included in provided links)
Thanks, I'll try and pick one up today and see what I come up with.
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Borrowed a vacuum gauge from my dad and have been checking my vacuum at different times and here's what I came up with.
Cold start, starts and idle at 600 for about 10 seconds, vacuum is at 14 psi, then idle bumps up to 850, idle come up to 17 psi.
Hot idle at 850, vacuum is between 18-19 psi.
From this, sounds like I have good vacuum right?
So vacuum tested good, fuel pressure tested good, what's the next step now? Either the cam or crank sensor?
Car hasn't stumbled on me in about a week. It seems like the o2 sensor helped some, but didn't cure it. Could it be air/fuel related?
I'd hate to take it to the dealer, bosch system seems like a pretty basic system, but I'm running out of stuff to check and things to swap.
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Yeah, vacuum sounds good. I have to admit I'm puzzled too. Now I'm just guessing, but could it be a bad injector? Maybe a flat spot somewhere on the AFM? I know you swapped that, might be worth a quick look under the AFM cover.
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Looks like you ruled out vacuum leaks.
Maybe it's not related, but the A/C idle bugs me.
The Electrical Manual, pg 77, Section 6452-2 discusses circuit operation of the A/C compressor controls (reference manual from this thread: http://www.m42club.com/forums/showthread.php?t=7748 courtesy of ak96ss). There's some good troubleshooting tables in there.
Some more crazy thoughts:
-What about the evap system? Is there something in there that could cause a problem like this?
-It sounds like the DME is getting signals, but they're mixed up. By any chance is it possible to cross the connectors between the temp gauge sender and the coolant temp sensor:confused:
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Yeah, vacuum sounds good. I have to admit I'm puzzled too. Now I'm just guessing, but could it be a bad injector? Maybe a flat spot somewhere on the AFM? I know you swapped that, might be worth a quick look under the AFM cover.
Popped the cover off the AFM before and cleaned the wiper with contact cleaner, didn't see anything that looked bad either. That was actually my first thought was the AFM was bad because of when it stumbled while rolling from a stoplight. I thought it was hitting a deadsopt and losing signal.
Looks like you ruled out vacuum leaks.
Maybe it's not related, but the A/C idle bugs me.
The Electrical Manual, pg 77, Section 6452-2 discusses circuit operation of the A/C compressor controls (reference manual from this thread: http://www.m42club.com/forums/showthread.php?t=7748 courtesy of ak96ss). There's some good troubleshooting tables in there.
Some more crazy thoughts:
-What about the evap system? Is there something in there that could cause a problem like this?
-It sounds like the DME is getting signals, but they're mixed up. By any chance is it possible to cross the connectors between the temp gauge sender and the coolant temp sensor:confused:
Yeah the A/C idle kills to me too. I'm wondering if the A/C switch would be casuing that? I also thought about the connectors too, but that would mean that the temp gauge wouldn't work at all right? Haven't thought about the EVAP system, don't know what would that would be.
The whole thing just boggles me, I just can't figure it out. It comes down to me just throwing parts at it until the problem goes away I guess. Sucks but I just can't figure it out.
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Yeah the A/C idle kills to me too. I'm wondering if the A/C switch would be casuing that? I also thought about the connectors too, but that would mean that the temp gauge wouldn't work at all right? Haven't thought about the EVAP system, don't know what would that would be.
The whole thing just boggles me, I just can't figure it out. It comes down to me just throwing parts at it until the problem goes away I guess. Sucks but I just can't figure it out.
I'm still thinking that the car is running well in open-loop and having this trouble when it goes closed-loop. The A/C high idle and cold idle is sent from the DME to the idle valve. You checked both the coolant sensors already, so I discounted this. Unless it's some odd wiring gremlin in the harness.
Don't throw parts at it. We'll figure it out...these are well put-together cars.
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I'm still thinking that the car is running well in open-loop and having this trouble when it goes closed-loop. The A/C high idle and cold idle is sent from the DME to the idle valve. You checked both the coolant sensors already, so I discounted this. Unless it's some odd wiring gremlin in the harness.
Don't throw parts at it. We'll figure it out...these are well put-together cars.
Well it used to stumble on cold starts sometimes, but since I put the new o2 on, it hasn't done it since, maybe luck, maybe it partially fixed it. The A/C idle isn't high, the idle drops down when I turn the A/C on, and when I turn it off, it shoots right back up. Only coolant sensor I changed was the one for the DME.
ONLY other thing besides the AFM possibly is the cam or crank sensor maybe is losing signal.
Like I stated before, it usually stumbles and bucks below 2k if I put a load on the engine is say 2nd or 3rd gear. I can get it stumble pretty good when the A/C's on and putting a load on it. Almost like a timing issue. Do the cam and crank sensor both play a role in timing?
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Both play a role in timing, but the cam sensor is the one that sets advance, along with coolant, air temp, AFM door, TPS, well pretty much all of them!
Odd that the O2 sensor helped cold idle. It really doesn't do much until it's heated up.
I'm not sure if we went over this, but did you test for cracked spark plug wires or just worn out plugs? Leaky wires would make lots of little gremlins for you.
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Both play a role in timing, but the cam sensor is the one that sets advance, along with coolant, air temp, AFM door, TPS, well pretty much all of them!
Odd that the O2 sensor helped cold idle. It really doesn't do much until it's heated up.
I'm not sure if we went over this, but did you test for cracked spark plug wires or just worn out plugs? Leaky wires would make lots of little gremlins for you.
Changed the spark plugs, ohmed out the wires, wires checked out good. I could change them if I need to.
AHHHHHH, this is annoying me!:mad:
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No miracles promised...
BMW issued a service bulletin 13 03 91 (3290) dated July 1991 for M42s produced between 2/90 and 12/90, last seven of serial #s EE65001-72808 for the 318is and EJ00000 - EJ05097 for the 318i.
Dealer has to run a check through their Dealer Communication System to see if a particular car gets the fix or not.
The next two paragraphs are verbatim quotes:
Situation: Due to an occasional impairment of the signal between the air flow meter potentiometer and the DME control unit, the engine idle may dip below specification at times causing a possible rough idle condition.
Correction: Adapter harness (P/N 13 62 1 734 516) must be installed on all affected vehicles between the engine wiring harness and the air flow meter. The adapter harness, which incorporates and impedance converter, filters and amplifies the signal from the air flow meter to the DME control unit.
Edit: Again the correct part # is (P/N 13 62 1 734 516), my original post had 61.
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No miracles promised...
BMW issued a service bulletin 13 03 91 (3290) dated July 1991 for M42s produced between 2/90 and 12/90, last seven of serial #s EE65001-72808 for the 318is and EJ00000 - EJ05097 for the 318i.
Dealer has to run a check through their Dealer Communication System to see if a particular car gets the fix or not.
The next two paragraphs are verbatim quotes:
Situation: Due to an occasional impairment of the signal between the air flow meter potentiometer and the DME control unit, the engine idle may dip below specification at times causing a possible rough idle condition.
Correction: Adapter harness (P/N 13 61 1 734 516) must be installed on all affected vehicles between the engine wiring harness and the air flow meter. The adapter harness, which incorporates and impedance converter, filters and amplifies the signal from the air flow meter to the DME control unit.
Hmmm, I'm gonna have to call on the dealer on this one to see what they say. That's what I've been saying the whole time, it almost acts like it loses signal from a sensor, stumbles, and then picks the signal back up and keeps going.
Also, thought the condition was getting better? WRONG. Started it up yesterday after it was sitting for a few days, as it was running, I was moving another car in the driveway and the car stumbled again.........again..............and again. It's never stumbled repeatedly.
So obviously everything I've put on it has done nothing. Hopefully this service bulletin will give me some higher hopes.
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No miracles promised...
BMW issued a service bulletin 13 03 91 (3290) dated July 1991 for M42s produced between 2/90 and 12/90, last seven of serial #s EE65001-72808 for the 318is and EJ00000 - EJ05097 for the 318i.
Dealer has to run a check through their Dealer Communication System to see if a particular car gets the fix or not.
The next two paragraphs are verbatim quotes:
Situation: Due to an occasional impairment of the signal between the air flow meter potentiometer and the DME control unit, the engine idle may dip below specification at times causing a possible rough idle condition.
Correction: Adapter harness (P/N 13 61 1 734 516) must be installed on all affected vehicles between the engine wiring harness and the air flow meter. The adapter harness, which incorporates and impedance converter, filters and amplifies the signal from the air flow meter to the DME control unit.
Just checked my mfg date and VIN and they both fall under the service bulletin. I'm gonna call my dealer now and see what they say.
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Called and service had to take my info down because they're short-handed today. Haven't heard back from them yet but I did talk to parts about that adapter harness part # and they said the number is no good.
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Called and service had to take my info down because they're short-handed today. Haven't heard back from them yet but I did talk to parts about that adapter harness part # and they said the number is no good.
Sorry I was off one on the part # re-read the bulletin and the correct number is (P/N 13 62 1 734 516).
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Sorry I was off one on the part # re-read the bulletin and the correct number is (P/N 13 62 1 734 516).
Thanks, I'll call monday and see what they say.
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Did a quick look at pelicanparts.com for the adapter cable 13 62 1 734 516, and it's $246.50.
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Aha! I wondered what that was...I pulled it out of mine to fix an AFM code! I'll post a pic of this ridiculous little piece of cable for you:
(http://i729.photobucket.com/albums/ww299/desktopdave/318i/th_IMG_1508.jpg) (http://s729.photobucket.com/albums/ww299/desktopdave/318i/?action=view¤t=IMG_1508.jpg)
Not worth $250 IMHO. I never figured there would be a pack of resistors there, but when I peeled back the cover, there it was.
I'll let you borrow it for troubleshooting if the BMW dealer won't help out.
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Did a quick look at pelicanparts.com for the adapter cable 13 62 1 734 516, and it's $246.50.
GOOD GOD!
Aha! I wondered what that was...I pulled it out of mine to fix an AFM code! I'll post a pic of this ridiculous little piece of cable for you:
(http://i729.photobucket.com/albums/ww299/desktopdave/318i/th_IMG_1508.jpg) (http://s729.photobucket.com/albums/ww299/desktopdave/318i/?action=view¤t=IMG_1508.jpg)
Not worth $250 IMHO. I never figured there would be a pack of resistors there, but when I peeled back the cover, there it was.
I'll let you borrow it for troubleshooting if the BMW dealer won't help out.
So you took the adapter out because it was giving you issues? Wonder if the resistors went bad? Are you still using it?
I would REALLY appreciate it if you would let me try it out. I would hate to drop $250 for an 1' harness that won't fix it.
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Found out that my car had it on already, removed it and drove it home from work, seemed to idle smoother, no stumble either. I probably should disconnect the batter to reset the DME to make sure it's good. Only bad thing is now I found a bad leak from my steering rack, so it parked until I can swap that out.
I'll update in a few weeks hopefully.
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I don't know if this will be the kissing cousin to the catalytic converter provision plug (hot start issue), as in disconnect things and performance improves.
Now leaking steering racks, that's more typical, albeit not much fun either.
Good luck sorting it out.
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Got the new rack on, but I still have my stumble, seems to do when it's cold, once it warms up, it doesn't do it much at all.
I have noticed that the idle is A LOT smoother without the harness adapter in. Even when the A/C's on, the car use to idle rougher, now it's better.
Next step is to replace the crank and cam sensor, we'll see what happens there.
I'm tired of troubleshooting, just gonna start throwing parts at it.:(
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+1 on the harness. Mine ran when I pulled it, though it was probably the CPS too.
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Thanks for the updates guys, as stated before I had similar issue with stumbling in subzero temps. Sortof forgot about it once the weather warmed up. I'll check to see if I have the harness in mine.
In the meantime, I ordered a new ICV. Will see what happens once the winter starts in Michigan.
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I know this my OLD thread, but I never gave an update and I thought I did so here you go:
After troubleshooting basically blind, I read on another site that a M42 owner was having a similar problem and found out it was ignition coil failing. So I was gonna try the COP kit, but ended up getting a used set of coils just to make sure that was the problem. Swapped them out and haven't had a problem since. I don't know how I would have found it if I didn't have talked to the other owner.
Hope this helps future troubleshooting!