M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: JHZR2 on July 30, 2008, 08:26:24 PM
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Hello,
My 91 318i runs like a top, good power, good mileage, etc. It always starts cold. However, when I start it hot, i.e. after using it for a while, and let it sit from 30 seconds to an hour or two... then it will start up and immediately, gracefully go right back to 0 rpm, i.e. stall. No odd noises, and this will happen multiple times.
If I give a little bit of gas, the car will stay running very easily, and then idle just fine - rock solid stable. And its not much gas, just 1500 RPM for about 5 seconds is all it takes.
The car starts, runs, idles, etc perfectly otherwise... There is no clear issue that exists. The fuel pump is recent, as though it wasnt exhibiting any problems, it was noisier than I thought it should be, and the connection was a bit flaky...
Any thoughts as to what it could be???
Thanks,
JMH
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Welcome to the club... been dealing with this since I bought my car in Feb. Changed all kinds of parts, but still no solution... keep us updated if you figure it out.
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Two things you can try:
1) remove the ICV valve and clean it - if you have never done it, it's possible it's carbon'd up inside. Get Brake cleaner and squirt a liberal amount inside, let it side for about 10 mins, shake it out and repeat 2 more times. After it's dry, then squirt WD40 inside of it, reinstall and your idle should be alot better than previously. The ICV regulates the air going into the engine for idle speed, driving, etc...
2) coolant temp sensor is malfunctioning, thus sending bad data to the DME. If the sensor is not able to determine or sense the correct temps for hot, warm or cold drivability, once the data is sent to the DME, the car could be dumping fuel or leaning out, which will affect drivability and hot/cold starts.
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Here's a link to the other thread with more things you can try. None of us have figured it out yet though... I think there are 3 or 4 of us working on it. http://www.m42club.com/forums/showthread.php?t=6077 (http://www.m42club.com/forums/showthread.php?t=6077)
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Hi, I am new and this is my first post. I am sort of relieved to see that I am not crazy and that other people are having the same problem. My wife drives a '91 318i sedan, and it has been doing the warm start stumble for as long as we have had it, a few years now. She loves the car and just considers the problem to be part of the cars personality, however as a dedicated car geek who does all my own work I find it to be like a rusty knife thrust into my soul. When we bought the car I replaced just about everything under the hood as far as sensors and hoses goes, and I have swapped in different coils, ECUs and AFMs and replaced the ICV and FPR in chasing the problem. Nothing has ever made a difference. The car always starts fine and drives great, until you shut it down and then attempt a warm start. Then it starts OK, but the idle will get rough and it will eventually stumble and die if you don't give it some pedal, sometimes a whole lot of pedal. You can keep it going this way, and after roughly 45 seconds it starts to run fine again until the next warm start. I eventually gave up trying to fix it and intalled a little button and a timer-relay that sends a bogus cold reading to the engine temp input to the ECU for like 30 seconds, this will help it run somewhat better until it clears up on its own. I am to the point that I am considering ripping the Motronic entirely and going MS2, but that is a lot of work on a car that is just a commutermobile and is otherwise stock. I have thought about welding in another O2 boss and temporarily putting in a wideband O2 to help figure out what is going on, I may still do this someday.
Daryl
'91 318i sedan, and a bunch of E28 535s.
(http://naskale.com/images/e30/main.jpg)
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My dad and I have been trying to figure out what the problem is with the warm rough start for a few years. We talked to a mechanic that we get some parts from and he mentioned that a fuel injector might be leaking extra fuel into one of the cylinders and making it idle rough until the extra fuel burns off. This seems to be good explanation for it, but we couldn't find any visual signs that one might be bad when we took it apart today. We just ordered 4 injectors. Hopefully this will help. We will probably install them on Wednesday. What do you guys think?
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My dad and I have been trying to figure out what the problem is with the warm rough start for a few years. We talked to a mechanic that we get some parts from and he mentioned that a fuel injector might be leaking extra fuel into one of the cylinders and making it idle rough until the extra fuel burns off. This seems to be good explanation for it, but we couldn't find any visual signs that one might be bad when we took it apart today. We just ordered 4 injectors. Hopefully this will help. We will probably install them on Wednesday. What do you guys think?
At least in the case of my car, I don't think a leaky injector could be the problem because the car will eventually stall if it is allowed to idle without touching the gas. One cylinder burning off extra fuel would not slowly kill the engine. Does your car stall if you let it idle after a warm start?
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A leaky injector could cause this but it would not only happen on warm.. it would happen most of the time. My guess would be the coolant sensor or vacuum lines. If not that just check the fuel pressure coming out of the fuel filter. Could be starving for fuel.
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My dad and I have been trying to figure out what the problem is with the warm rough start for a few years. We talked to a mechanic that we get some parts from and he mentioned that a fuel injector might be leaking extra fuel into one of the cylinders and making it idle rough until the extra fuel burns off. This seems to be good explanation for it, but we couldn't find any visual signs that one might be bad when we took it apart today. We just ordered 4 injectors. Hopefully this will help. We will probably install them on Wednesday. What do you guys think?
I replaced my injectors even though i wasn't 100% sure they were bad.. I gained about 10mpg just by replacing them. It was more than worth it even though it didn't fix my stall issue. I am very happy that i replaced my entire fuel system.
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The fuel injectors were delivered today.
I replaced my injectors even though i wasn't 100% sure they were bad.. I gained about 10mpg just by replacing them. It was more than worth it even though it didn't fix my stall issue. I am very happy that i replaced my entire fuel system.
That makes me feel better about spending $250 even though it won't fix the problem.
Has anyone who had this problem successfully fixed it by doing any of the things mentioned? It seems like nobody has had any luck.
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The fuel injectors were delivered today.
That makes me feel better about spending $250 even though it won't fix the problem.
Has anyone who had this problem successfully fixed it by doing any of the things mentioned? It seems like nobody has had any luck.
You should have shopped around and tested the fuel pressure before spending 250.. 222 for a fuel pump on rockauto, same price as an employee gets the bosch for at my local dealer. I paid 26 per injectors off rockauto.
I've learned from buying tons and tons of parts that even if it doesn't fix your issue it prevents one in the future. Why not replace an o2 sensor if you dont know the mileage on it?
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Has anyone who had this problem successfully fixed it by doing any of the things mentioned? It seems like nobody has had any luck.
Nope no luck. Just fixed my exhaust leaks and still no luck. Even worse I stopped by a dealer who had a low mileage ~150k 318is 91 and it started right up and idled awesome. Sounded way healthier than my 34k motor. Pissed me off :) For some reason my engine sounds way raspier than the other one did.
I'm having my mechanic pull the valve cover and check the timing to see if it is in spec for the Delta regrinds. I'd switch back to stock cams if I thought it would help... but so many ppl with stock cams have this exact same issue. Becoming a real thorn in my side.
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This problem has plagued me for nearly 2 years now as well.
It seemed to have begun immediately after I cleaned out my ISV and AFM with TB cleaner and attempted a hot air intake install. I've attempted and done the following with no joy.
Tried a known good AFM
made sure fuel pump connections were tight
(fuel pump 3 years old)
replaced all the hoses below the intake manifold
fuel injection cleaner
replaced with known good FPR
went back to stock airbox
just wanted to add this in to this official thread - i've almost come to accept my old e30 likes make me look bad in front of a group of people as it always does this only in front of an audience, not when we're alone :D
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^LOL consider yourself lucky then, because mine does it all the time... unless I let her sit there and idle for 2 minutes before trying to drive off. LOL it pisses ppl off in busy parking lots. "Why aren't you pulling out already!!!!????";)
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"Why aren't you pulling out already!!!!????";)
LOL i get the same thing. I have replaced tons of shit and have fixed up my idle issue but its still present. I am pretty sure its either the coolant sensor or the cam sensor but people freak out when my car is running in that nice front row spot and im not pulling out forever. sometimes i say a little extra longer just so they move on to the next spot than i pull out.
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Has anyone tried swapping their Engine ECU. Test all ECU inputs first, if they check out, replace/swap the ECU.
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^I've replaced the ECU... but have not tested the pinouts on the harness. Changing ECU's didn't help.
I want to try the cam sensor... only sensor I have not replaced yet... lol. The crank sensor wouldn't have any effect would it? Oh and do our cars have a "Thermal Time Switch". That's what a couple of friends said would be worth looking into.
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^I've replaced the ECU... but have not tested the pinouts on the harness. Changing ECU's didn't help.
I want to try the cam sensor... only sensor I have not replaced yet... lol. The crank sensor wouldn't have any effect would it? Oh and do our cars have a "Thermal Time Switch". That's what a couple of friends said would be worth looking into.
I don't think i've ever heard of a thermal time switch in a M42, i'm pretty sure our ECU is smart enough to figure out what the engine is hot and when its cold( no cold start). not 100% on that but 99%, get a new cam sensor off pelican and let me know, either way i'm gonna order myself a new cam sensor just because i want my car to run like it did in 1991
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Bump... you try that cam sensor? I haven't had the time/extra cash to order one yet.
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Ok, so it seems alot of guys have changed nearly every sensor on the engine with no result. Try looking for any breaks in the engine wiring harness, also check engine earth straps. Check wiring for short circuits.
I remember working on OBD-II vehicle that had a warm start stalling issue, it ended up being a blocked carbon canister. It may not be related in this case but hey it could be worth ltaking a look at.
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^I was wondering if the carbon canister could be causing any kind of problem. It has to be something external to the engine. I talked to the original owner of the motor I bought and he said it had no problems. Then talked to the dealer I bought the car from and he said the old motor exhibited the same starting issues. After 2 mins it ran fine.
So it has to be something external to the engine that didn't get swapped in. IE: brake booster vacuum (brakes feel a tad weak, but I'm coming from an e46), carbon canister, wiring harness, coils, or plug wires. Any suggestions on where to start?
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I would first look into the wiring harness. Inspect wiring for damage, short circuits etc. Also if it was throwing up a oxygen sensor fault, inspect the wiring and the routing of the wiring from the sensor to the ecu. Then after that inspect all vacuum lines, breather pipes, and look for any air/vacuum leaks particularly around the intake manifold.
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^I was wondering if the carbon canister could be causing any kind of problem. It has to be something external to the engine. I talked to the original owner of the motor I bought and he said it had no problems. Then talked to the dealer I bought the car from and he said the old motor exhibited the same starting issues. After 2 mins it ran fine.
So it has to be something external to the engine that didn't get swapped in. IE: brake booster vacuum (brakes feel a tad weak, but I'm coming from an e46), carbon canister, wiring harness, coils, or plug wires. Any suggestions on where to start?
FWIW, my brakes feel very weak, but I've always attributed that to never getting around to flushing it with new good fluid.
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^Mine has been flushed and bled with new good fluid... and still feels weak. I thought it was my MC or something, but maybe it's the booster.
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^Mine has been flushed and bled with new good fluid... and still feels weak. I thought it was my MC or something, but maybe it's the booster.
I noticed when fudging with hoses, i've accidentally tugged the vacuum line to brake booster and you hear the hiss but i've always pushed it back on, should it be so loose that we can just tug on it and it creates a massive leak?
Just a shot in the dark.
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Mine feels very loose as well... can anyone with a car that idles properly chime in as to whether that is normal?
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I've tried a camshaft sensor on mine and that didn't help. Also after today's hot restart the antilock brake light came on, that's a new one.
I had a Mitsu Galant VR-4 once and one time it started dieing and it turned out to be the alternator, reason I mention this is that the antilock brake light came on while this was happening, the alternator light never came on. Apparently the antilock system is much more sensitive to low voltage than the rest of the car.
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Drove it a while today, the antilock light is out and the car ran great. Put a voltmeter on it and all is well there too. I hate intermittent crap.
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Mine feels very loose as well... can anyone with a car that idles properly chime in as to whether that is normal?
Next time my car does it, i'll jump out and try to push/tighten the the brake vacuum host to the booster and see what happens.
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Next time my car does it, i'll jump out and try to push/tighten the the brake vacuum host to the booster and see what happens.
I just tried it... didn't do anything for me. I think if the problem is a vacuum problem with the booster, it's internal and only way to fix is to replace the booster. No way to confirm this is the actual problem though, or that it is even a problem. Ahhhh how I love troubleshooting hard to find problems.
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A faulty brake booster will not cause stalling of the engine. Has anyone tried or checked anything else regarding the stalling problem when hot?
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A faulty brake booster will not cause stalling of the engine. Has anyone tried or checked anything else regarding the stalling problem when hot?
Sure have, below is everything I've checked/replaced
1. ICV (replaced)
2. Vacuum Leaks (did TB heater delete and replaced hoses)
3. o2 Sensor (replaced)
4. Plugs & Wires (replaced as part of maintenance)
5. Fuel Injectors (mustang 19#)
6. Exhaust Header Gasket (had a leak)
7. AFM (replaced)
8. Engine Temp Sensor (replaced)
9. Throttle Position Sensor (replaced)
10. Fuel Pressure (40-50lbs)
11. Smoke tested (ok)
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Im having the same issue guys.... I really havent looked into it much. For me it runs great under cold starting conditions. As soon as the motor is shut off and restarted it idles rough and you can smell the massive rich condition... All I do it give the car full throttle under load a few times and it fixes itself. I have replaced the O2 sensor and the coolant temp sensor. It all started happening after I replaced the alternator and fuel pump. Im going to make sure the evap system is breathing like it should. Its rather annoying.
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Mine seems to happen more on hotter days and I too notice the fuel smell. Sometimes it just stumbles and idles very poorly, other times the engine will die but start right up and run fine.
Sometimes the check engine light will come on when it is stumbling, that usually only happens when the engine goes on to die. The CEL never stays on and is always off on the restart.
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ok, i put this in the other thread, but i thought it should be in both threads.
as we all know, the m42 vibrates quite a bit.... wires don't like to vibrate.
has anyone tried replacing their fuel pressure regulator?
Fixed my similar problems to your guys.
my point is, check all of your plugs, pull the rubber sleeve back on your plugs, and check for loose or broken wires, a multi meter works good too. I have experienced this on 3 separate occasions.
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My fuel pressure is 41 psi steady,
your fuel pressure should not be wavering around at idle...
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Mine seems to happen more on hotter days and I too notice the fuel smell. Sometimes it just stumbles and idles very poorly, other times the engine will die but start right up and run fine.
Sometimes the check engine light will come on when it is stumbling, that usually only happens when the engine goes on to die. The CEL never stays on and is always off on the restart.
have you done the stomp test to see which code it gives you??
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Kowalski... betting the only code that comes up is 1222. My fuel pressure is 40-50psi according to the shop that tested it for me (specializes in BMW's taken all 5 of my bimmers there for hard to find problems and this is the first time they are stumped). They want to check the timing. I don't think that's the issue though.
As I said in the other thread... I will replace the FPR (for peace of mind), and recheck my new plugs/wires. Will let you guys know if I find anything.
If we keep at it... one of us HAS to figure out the culprit. LOL there are now 10+ ppl suffering from it on this board alone.
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Kowalski... betting the only code that comes up is 1222. My fuel pressure is 40-50psi according to the shop that tested it for me (specializes in BMW's taken all 5 of my bimmers there for hard to find problems and this is the first time they are stumped). They want to check the timing. I don't think that's the issue though.
As I said in the other thread... I will replace the FPR (for peace of mind), and recheck my new plugs/wires. Will let you guys know if I find anything.
If we keep at it... one of us HAS to figure out the culprit. LOL there are now 10+ ppl suffering from it on this board alone.
while your at it you should tel the 4 wire plug for the TPS, pull back the rubber and inspect each wire and connector.
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^Will do... but I can't see it being wiring. Doesn't happen over bumps or anything like that. Only on initial starts. My main engine ground is a good bit worn... will replace that, but not holding my breath.
Haven't had time to check out the other suggestions yet... I am remodeling a bath and bedroom in our house preparing for a sale. Hasn't left me much time to work on a problem with the car that is basically just an annoyance. LOL albeit a VERY big annoyance.
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let me know when your done.
If its ONLY doing it when warm, you should test the resistance of your cam and crank sensors when warm. they have a cold test rating, and a warm test rating...
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I have the same problem and have replaced the FPR...
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I have the same problem and have replaced the FPR...
this problem can be caused by a multitude of things, its something that is on its way to failing.
My suggestion is to test everything thats free, get a multi meter and check all your sensors and wiring, then move on to other things.
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this problem can be caused by a multitude of things, its something that is on its way to failing.
My suggestion is to test everything thats free, get a multi meter and check all your sensors and wiring, then move on to other things.
I have tested and replaced pretty much everything thats been listed in this thread.
I wish it would just fail so i can replace it already.
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Well, checked the 3 wire plug at the TPS and the 2 wire one at the ICV. Both are fine and wiring actually looks fairly new. I want to check the long plastic box under the intake that houses all the wiring for any problems, but I'm not holding my breath. Waiting on my new engine ground to get here...
I swear I can hear a whistle, like a vacuum leak from in front of the intake. But all those hoses/lines were replaced. I'll inspect all those lines VERY carefully next time I have the intake off to check those wires.
Anyone else make any progress?
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I really think the OP problem is a sensor, thinking about it:
1. Only on hot starts he has a problem, if it was a vacuum leak it would happen every time you start your car, like mine
2. Cold starts he is fine, there is a signal that is able to be read when cold, but hot not...
I would really lean toward sensor on this one.
My problem exist whether the car is cold or hot -> leads me to sensor & vacuum leak
Only time it doesn't do anything is when its really cool outside, temp , and the car has been sitting for a while like overnight
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My car has been doing funny things ALMOST like this. It started just like the OP described and got worse from there. By the time I started getting massive power loss as I accelerated and the inability to re-start the motor after shopping on the hottest day of the year, I decided to take care of "the mess under the intake." no change. In fact, I think it's even worse. I also replaced the O2 sensor, so I'm thinking fuel pressure (or AFM... or temp sensor... but the stomp test gives the all-clear)
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Massive power loss...get the tester on fuel pressure. Let us know what you find.
I wonder if this has something to do with the BMW resistor pack on the AFM harness? I had one installed on my e30, does anyone else? It's an extension plug that BMW installed as a TSB...might be that it's changing the intake air temp sensor reading. If the IAT is wrong, the car will run pig rich, spark plugs won't fire & you'll get no start and strong smell of gas.
I'll test my TSB resistor pack later & report my findings.
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I recently bought a 1991 318i (M42) for my son's first car and it had the same problem. It started fine cold but after being shut down hot for more than a couple of minutes it would start fine then begin to idle rough and if you attempted to drive it would surge and come close to stalling. If you let it idle for a minute or reved it up over 3000 RPM OR shut it off and restarted it would clear itself and be fine until the next hot start.
The solution turned out to be a very simple one. There is a single wire connector in the wiring harness under the cover on the firewall covering the DME/Fuel Pump/O2 Sensor relays that should be disconnected if the car has a catalytic converter and connected if it doesn't. I disconnected this connector and everything is fine! I wish I did this first however on the bright side I have a spare of pretty much every sensor plus a ECU (Luckily I got them cheap on ebay).
We have only had the car a couple of months and I must say I've learned a lot about it and love it. It is excellent to work on and a pleasure to drive. I'm looking for a clean '91 is for myself! I hope this helps someone as it seems we weren't the only ones troubleshooting this snag.
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There's a long post somewhere about that CO plug in the harness...I'm glad you've fixed it though. Post your spares up in the WTB classifieds section.
Welcome to the 'club, BTW...we're always looking for new members, especially if they're decent mechanics!