M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: Stück on August 19, 2007, 09:54:44 AM
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I have an interesting hesitation that is giving me a hard time on my recently purchased 91 318iS.
It does it worst and most consistently at cold, but often when warm it will do it much "softer" so much so its almost not at all.
Off idle if you apply the throttle quickly it will start hesitation, it feels like its only hitting on 2 cylinders and there is a distinct miss sound. If you ease up on the pedal it does seem to do it less. Once the engine reaches the 1500-2000rpm range it completely stops the hesitation and will eagerly rip to redline gear after gear.
Outside of that RPM range off idle the problem is not present.
I've already checked all the hoses I can see for vacuum leaks, I'm reasonably sure there are not any. I've worked on quite a few m42s and am familiar with the rats nest under the manifold.
The engine does hold a smooth steady idle, with or without the AC on.
Any suggestions on where to start?
So far I have:
Removed the spark plugs. They looks like fairly new Bosch +2's
Removed the crank & cam position sensors and cleaned the grease cakes off them.
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The hot vs. cold has me wondering a bit; my first impulse would be to say to check the AFM or TPS, but those shouldn't really be any different hot or cold - I would expect them to exhibit the same symptoms all the time.
Don't have a spare DME there do you?
I wish mine would idle smoothly. I get a lovely hunt, but only when the engine is hot. Cold idle is steady.
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I dont have a spare ECU no.
I'm kinda leaning towards it being the cam position sensor. I know on my e36 M3 when it went bad on me it displayed similar symptoms. Same busted ass missing through some RPM ranges, and others it was fine... until it stopped working altogether.
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Have you checked the condition of the spark plug wires?
I had a similar issue with my car about a year ago.
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I have not removed them all to verify condition, but from what I can see they look ok? That is a good idea though. Next time I have a chance I will pull off the cover plate, start the engine, turn out the lights... and look for arching.
I wouldn't *think* this would be the problem though, as it runs fine past a certain RPM.
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Just checked for arching in the dark... nothing.
Also pulled easy plug wire off the plug with the engine running and listened, all produce a nice spark while hovered above the plug. Each when pulled fully away produces the normal dropped cylinder running.
Don't think its a spark issue, at least not on the side of the coils/wires/plugs
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I would say cam pos. sensor. sounds like the problem i had as well and fixed it with that. as well i would check the MAF, the engine is mostly in those RPM's and the carbon strip could be worn out on the path for the lower rpms throwing off the signal.
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I would say cam pos. sensor. sounds like the problem i had as well and fixed it with that. as well i would check the MAF, the engine is mostly in those RPM's and the carbon strip could be worn out on the path for the lower rpms throwing off the signal.
+1 on camshaft position sensor... mine whas like it misfired when it was bad, it had a bad idle and car was losing a bit of torque too..;) but I changed it at the same time of lambda sensor, that was bad too.. now the car is like new:)
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The hot vs. cold has me wondering a bit; my first impulse would be to say to check the AFM or TPS, but those shouldn't really be any different hot or cold - I would expect them to exhibit the same symptoms all the time.
Well the basic air fuel mixture equation shows the coolant temp sensor as well as the AFM and the ECU as other players in the party.
These engines are sensitive with the air intake path as we all know and since his spark seems to be 100% I'd start off with cleaning/testing the AFM. It's annoying to open up an AFM but they can be sealed back easily as we all know.
I had a tempermental issue that was related to the AFM at one point. Do you have one to swap with?
The other I had which was related to throttle application was the TPS wires being frayed in the sheath/sleeve of the connector.
One time my cam sensor came loose on the track and the car had a odd stuttering issue.
G. Luck
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I had a similar issue on mine and it turned out to be the AFM. It was pretty intermittent (though consistent enough to really piss me off), but after installing my MAF conversion over a year ago I have not had one problem/misfire. I tried testing the AFM with an Ohmmeter and there were no resistance jumps. I still cannot say what it was in the AFM that was messing up for sure, but I an 99% sure it was that. *knocks on wood*
My guess about it was that the volume of air flowing around the range you are describing is where the AFM parts spend most of their time when cruising, and the carbon track just gets a little worn there. Maybe the thermal expansion in some of the parts is just enough to put the follower in a badly worn groove or something. Good luck, keep us posted!
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I will pop the top on the AFM this afternoon. I've had to bent the arms before to account for a worn track back when I had a AFM on my 328iS. Fixed it then, would be nice if it was the same deal since that is free :)
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Opened the AFM, cover has never been off before. The carbon tracks look very nice and the resistance range is steady.
While I was there I decided to OHM out the cam and crank position sensors. Car has been parked about 30mins or so from fully heated up.
Crank sensor was 610ohms.
Cam sensor was 1480ohms.
Seems to be the cam sensor is WAY outside of range..... thoughts?
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According to the factory manual, the cam sensor should be 1150 - 1410 Ohms. The crank sensor should be 540 +/- 60 Ohms.
Taken from:
http://ee1394.com/bmw/docs/factory/repair/en/index1.htm which can be downloaded from a link in the Reference Forum.
(http://ee1394.com/bmw/docs/factory/repair/en/repair/images/0215.jpg)
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Eh.. so maybe its not that then.
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Haha well, if this is your daily driver then I probably know how you feel. I tested everything repeatedly, tried disconnecting various sensors to see if it would at least run better in "limp" mode, you name it (though I did not try it without the AFM connected...that never goes too well). It seemed extremely unlikely that it was the AFM causing the cut-out, but ended up being that. A few other guys on here have had the same issues, and remedied them by replacing the AFM.
If you want to try a "good" one out let me know. The one from my car gave me no troubles when I smogged it a month ago. It seemed to get bad only in cold weather. For the cost of shipping you can borrow mine if you like. It'd probably be around $12. Then again, if you still get parts hookups or have a Worldpac account then you can probably get a new one cheap.
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Appreciate that, I may take you up on it if it comes to that.
I just did a stomp test. The only code stored is:
1216 Throttle Potentiometer
Tell me what to look for to substantiate the code.
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I suspected mine for a short while. Unplug it and see if it stumbles. It should not stumble with the TPS disconnected, just run a bit rich. We'll see from there.
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If I disconnect the TPS at idle the engine shuts off.
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That's interesting. Even if you disconnect it when the car is off then restart it?
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I can restart the car with it disconnected and it idles fine, revs in the same stumbling manner. Basically nothing changes.
Starting it with the cam sensor disconnected does not change the stumble either.
Also idles fine with the AFM disconnected, although it runs/revs like poo poo (to be expected)
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Appreciate that, I may take you up on it if it comes to that.
I just did a stomp test. The only code stored is:
1216 Throttle Potentiometer
Tell me what to look for to substantiate the code.
Plug it back in - while at idle - wiggle the connector and see if the idle fluctuates....that will provide an indication as to you having a frayed wire or not. IIRC - there are 3 wires for it in the sheath.
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You know, this is beginning to sound very much like the issue I had.
I had the 1216 error code as well. I tried swapping AFM's, I bought a new TPS sensor, cleaned everything out, inspected the wires...
It turned out to be my ECU! See if you can get your hands on a stock ECU...
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You know, this is beginning to sound very much like the issue I had.
I had the 1216 error code as well. I tried swapping AFM's, I bought a new TPS sensor, cleaned everything out, inspected the wires...
It turned out to be my ECU! See if you can get your hands on a stock ECU...
Wow, that really sucks. Hope you got a good deal!
I have a spare 175 DME somewhere in here. I did a lot of experimenting on it, but as far as I can tell it was not damaged. That is up for borrowing as well, though I have not tested it since digging around in it. Eventually it will be my testbed for a car simulator so I can REALLY get an idea for how it handles various inputs. Anyway.....
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I got lucky, my friend had one.
I bought it for $30 =)
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Plug it back in - while at idle - wiggle the connector and see if the idle fluctuates....that will provide an indication as to you having a frayed wire or not. IIRC - there are 3 wires for it in the sheath.
I forgot to mention I pulled back the boot and the wires all looked choice. No problem here.
While trying to slide the throttle body off the studs enough to remove the TPS to examine it the tiny hose that goes between the TV heaters poped on me and puked coolant everywhere :mad: Thats fine though.. just gives me a reason to tear that *feature* out and bypass.
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If you believe the wires can't be frayed elsewhere - it could be a false signal from the diagnostic or something else AFM may be causing it. If the AFM passes the visual and readout test - try see if you can get another ECU to swap out.
I don't remember but is this issue new or was it pre-existing at purchase?
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I think he said it was preexisting.
I think it is safe to say it has been narrowed down to either the AFM or the ECU. From your inspection of the AFM it sounds like that is probably OK. If only the ECU was easy to inspect visually.....
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{mumbles in the background}
Didn't I mention that...
/mumble
:D
I have an extra ECU if you want to borrow it, or one I can sell you if you like. Either/or - I actually have two spares, I believe both to work fine.
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It is a prexisting issue.
I put everything back together sans the TB heaters and with a new FPR hose as the old one was wasted. I drove out to some favored back roads and proceeded to get on it. Put the car through its paces until I had to cool off because the brake pedal was just about useless... going to have to correct that some time soon too.
Anyways this is the first time I've really taken it out of city streets and had the ability to play with it.
If I take off from a rolling start in 1st gear at 800rpm or so (basically idling forward) and just hold WOT it will stutter all the way to redline without letting up. If I ease up just a bit then pound it back down it will stop the BS and pull cleanly. I was able to get it to do this consistently.
It will still stutter to redline if I give it too much throttle (but not WOT) off the roll, and hold it there.
While I had the TB off I removed the TPS and opened it up. All the wire/solder connections look very good, as does the carbon track. I bent the needles down a bit to ensure good contact and put it back together... obviously no difference there.
I should get Teaguer on the horn and see if I can drive over there and swap out with his AFM and ECU as he is local.
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That really kinda sounds like an ECU issue. Such intermittent and tempermental behavior is really odd. I would think any sensor issues would be consistent regardless of what you do before flooring it. I could always be wrong though, just when everyone thinks all the M42 gremlins were busted, a new one usually surfaces.
My issue was the opposite...stumbled horribly at part-throttle/low load, and went away on WOT.
Although unlikely, it could be the TPS still. Maybe it is vibrating internally causing voltage jumps and tossing the ECU in and out of open/closed loop running. Re-flooring it might resettle the contactor inside. Doubtful though.
I am betting on ECU at this point. Hit the T man for a spare.
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I just called him, his phone is shut off... PWNED!!
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I had similar problems and after much checking and testing and replacing numerous sensors it turned out to be one of my coils .So I replaced all four and the car has run sweet since.
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How much did you pay for the car? Since there are a number of small items on these that seem to be having problems at or above 120k miles, you might want to look into an overhaul of the parts that go south around now.
From what I can tell, a high percentage of M42's seem to get neglected by owners before they are sold to "enthusiast" types. Maybe it is because it is "just a 318" or something like thatm but a lot of these seem to miss some basic maintenance before being sold to people here. They really ARE trouble free motors once they have been refreshed and brought back up to snuff. Maybe the M20 world is the same way as well, but I would not know about that personally. Either way, it is annoying having to fix someone else's neglect.
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The M20 world is worse. Especially 2.5.:D
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I picked up the car for $1500, and yes it does need some work. Nothing I'm afraid of though. Really the first major thing is getting the engine running to its full potential.
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OK, Teaguer called me back. I'm going to run over to his place tomorrow afternoon and borrow his ECU, AFM, and coilpack. Is there anything else I should take off his car to try on mine while I'm there?
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I am having a similar problem but not at WOT. It misses a small amount when first depressing the accelerator then smoothes out. It will do this in all gears. The idle is perfect with ac on or off. I have replace the coils, plugs wires and the AFM...no change.
Any ideas? Seems like the concensus is the computer or the cam position sensor. Could it be something as simple as a fuel filter that needs changing?
As always, you guys are a wealth of knowledge!
Thanks
Matt
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Could it be something as simple as a fuel filter that needs changing?
As always, you guys are a wealth of knowledge!
Thanks
Matt
When my fuel filter was clogged, the car would stutter under load and you could tell it was a fuel delivery issue as the fuel economy gauge wasn't acting normally. Gotta love how it aids in troubleshooting :D
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ahhh, gotcha...makes sense....this is not a fuel delivery issue i think....
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ok, started the car last night and it ran like total shi*....missed horribly all the way home. what would cause it running somewhat decent in the morning but like garbage in the afternoon? I am at a loss at this point.
Thanks
Matt
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ok, started the car last night and it ran like total shi*....missed horribly all the way home. what would cause it running somewhat decent in the morning but like garbage in the afternoon? I am at a loss at this point.
Thanks
Matt
thread highjacker!!!!!!!!!!!!!!!
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OK, so updates on MY car and MY thread ;)
I picked up the ECU, AFM, and coil pack out of Teaguers good running 318iS last night.
I swapped each part onto my 318iS one by one, starting with the coil packs, then the AFM, and lastly the ECU.
No change what so ever.
Fresh ideas?
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I haven't read where you've checked and cleaned the ICV ??
When you got the code for the TPS did you check it or replace it . I doubt it could be the TPS but ??
I love a mystery.
good luck
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i bet its the carnk or cam sensor. or tps
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I haven't read where you've checked and cleaned the ICV ??
When you got the code for the TPS did you check it or replace it . I doubt it could be the TPS but ??
I love a mystery.
good luck
I don't see how the ICV is going to affect the engine up to redline. Off idle it has no means to do anything.
I checked the TPS, opened it up, everything looks good. It also OHM'ed out fine.
i bet its the carnk or cam sensor. or tps
I don't think it is the TPS as said before.. it tests and looks fine. The symptom also does not change with the TPS unplugged. It runs exactly the same.
The crank sensor generally works or doesn't and the engine will not start or run without it. Doesn't mean that is not a possibility though, I have not yet counted it out.
The cam sensor won't affect drivability. It is little more then a cylinder identifier as I have found out. If it is working then the ECU fires the injectors semi-sequential (2 banks of 2) if it is not working, or is spitting out a bad sinewave the ECU fires the injectors in parallel (all at the same time) You can (and I have) unlplugged the sensor with the engine running and it doesn't bother it.
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If you're 1000% sure the wire is intact....the pondering continues.
If not...are you still getting the TPS fault code? Does it look like s.one ever got in there to work on the rats nest of hoses? What basically happens is s.one might have forgotten to disconnect it and pulled too hard on it.
I would suggest to check the wiring and not the TPS. With the TPS disconnected, are you getting the same fault code? With the wiring being faulty - plugging or unplugging the TPS makes no difference. Does anyone remember if their car runs with the TPS unplugged? I don't think mine was driveable and able to run right but this was a while ago and my other m42 isn't here to test.
I don't have an m42 immediately near me but I think some of the wires and connectors can be disconnected from the main harness (black box under the manifold or so?). Is this one of those wires?
If not and the wire is inseparable you might have to tap into it and use another connector to bypass the stock connector and plug it into the TPS.
I did this same thing using the female connector that suprisingly slotted right in to the TPS. I can't remember exactly where it came from though as it came from my parts stash :confused: you can rig something though in case you don't have a spare connector to hack up
G.Luck
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I actually just finished pulling the braces and junk out, and sliding the engine bay side of the harness out from under the manifold.. to on top where I can sort through everything.
No breaks to be seen, no corrosion, no anything. Everything looks choice. I followed it up the big accorian and pulled it back, everything under it looks good.
Removed the wrap on the part of the harness that runs under the cover. Best I can see that bundle is undisturbed and happy.
I pulled back the boots on each BOSCH connector as far as I could, everything looked good. Same for the C101 and the diagnostic connector. Both pulse sensors, and the knock sensor connections at the under manifold wiring box looks great.
The connector at the ECU also looks pretty good. If someone has the PINOUT for the ECU connector ready I'd like to meter out all 3 TPS wires between the TPS connector and the ECU connector.
(http://oldmary.lqhome.com/~jordansarette/coppermine/albums/318iS/Pictures/2007/August%202007/normal_082307-001.JPG) (http://oldmary.lqhome.com/~jordansarette/coppermine/albums/318iS/Pictures/2007/August%202007/082307-001.JPG)
Oh.. and if the TPS is disconnected with the engine running the CHECK ENGINE light is illuminated steadily.
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I found all the wiring diagrams and connector pinouts I needed on line this afternoon, and went ahead with testing. All the TPS wires OHM'ed out 0.0 as they should, from the BOSCH TPS connector to the ECU connector. Wiring there is not an issue.
I wonder *if* and this is a big if... if the fault code might actually be legitimate despite the TPS passing the resistance test and visual inspection.
Later tonight, or possibly tomorrow after I reassemble everything I will test the voltages present on the TPS through its range of motion with the engine running... as is the only real important test.
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OK. All is back together.
With the key on I conducted a voltage test at pin 1 and 2 on the TPS with the connector plugged in (metered with the boot off)
What I found is um.. odd.
BMW spec is:
0.6v @ idle (throttle completely closed)
4.2v @ WOT
My TPS meters out as:
4.36v @ idle
1.08v @ WOT
What the fug? Ha ha... I now understand completely where the code is coming from. Proof positive that a simple resistance test (which it passed perfectly) is NOT a conclusive test.
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Interesting. Either you measured the wrong end of the pot wiper (unlikely since you ave the wiring diagrams), or somehow the pins in the connector ended up backwards. Did the previous owner have any repairs done on it? Weird.
Is the CEL on at all times when driving? The ECU is adaptive to the TPS sensor to accommodate the tolerances in the resistor track, but I doubt it can adapt to a reversed voltage output! You certainly got a mystery vehicle there!
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Pin numbers and wire colors indicate everything is as it should be, its not a negative voltage problem... which would come with flopped wires, but rather a backwards voltage swing of a slightly different range.
New TPS is on its way, should show up sometime next week.
CEL is never on, but the stop test shows the stored 1216 TPS code. If I start the engine with the TPS disconnected the CEL is on.
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Alrighty, well good luck with the new TPS. Let's hope that is all it was.
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Finally got around to installing the new TPS.
Nothing has changed :(
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After going through everything I can think of I decided it was time to pull the valve cover off and take a peek. The instant I did I could see the timing was off.
The intake cam was nearly dead on, but the exhaust was very advanced. Even backing it off in the slot as much as I could it still wasn't on. I had to pop the sprocket off and rotate it over a tooth to get the adjustment right.
Synced everything up and put it back together. Engine runs MUCH better now, although it is still exhibiting dulated symptoms of what it was doing previously. It is leaps and bounds better though.
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Wow......
How did the timing chain look? Do you know anything about the history of the motor / when or if the timing assembly was ever rebuilt? Usually by 130k miles a complete teardown & rebuild is a good idea, especially if a bad timing chain tensioner piston was ran for a while. I forget...did you pull the lower oil pan and look for junk?
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I have pulled the lower pan, it was immaculate. I checked and loctited all the bolts...
The timing chain and gears appear to have been replaced, all the rails look good, and the tensioner feels good. I have a feeling the timing was screwed up during that service...
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Anyone got any more guesses?
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switch crank and cam sensors with someone
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Cam sensor isn't required for the engine to run at all. You can unplug it with the engine running and it won't do anything but make the ECU switch to parallel injection (normally runs semi-sequential)
I'd like to swap crank sensors to run that out but mine is run wrong. Some retard ran it behind the AC compressor so getting it out would require either cutting it, or unbolting the compressor.
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lol
Sounds like whoever worked on the car last was a real idiot. I was unaware that it could even reach that far over. Then again I have not had AC in the car in so long I do not even remember exactly where the bracket sits. IIRC though, to get it running over that far the cable was probably damaged a little.
You said it runs great at idle and part throttle now, and only bad at WOT? If it really does run just fune after re-flooring it, it kinda rules out the cam/crank sensors to me. The cam sensor COULD be causing problems. It does 2 things:
- tells the motronic to use batcked or banked injection
- tell the motronic whether or not to run in true spark-per-cylinder mode or wasted spark mode.
Perhaps the exhaust cam is a little off still (I believe that is the one the sensor reads from) and throws the timing a little?
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you can always put an additional crank sensor on without taking the other one off
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u guys seem to have the knowledge that i'v been looking for maybe u guys can help me out with my problem...
this is the thread-------->http://m42club.com/forums/showthread.php?t=3695
please helpppp!!!!!!!!!!!
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I created a video for you guys since maybe my description is lacking. Virtual test drive FTW!!
Note that I have purposely driven in a manner that makes it do it as bad as possible so its very clear in the video.
http://oldmary.lqhome.com/~jordansarette/Runsbad.wmv (3.5MB)
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I had similar problems and after much checking and testing and replacing numerous sensors it turned out to be one of my coils .So I replaced all four and the car has run sweet since.
Had the same behavior, and replaced all four coils. Problem solved.
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Had the same behavior, and replaced all four coils. Problem solved.
I think he's swapped out the coils and still has a problem although when my coil was bad it was alot worse than what the video showed .
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Yeah, I have swapped out the coil pack with one from a perfectly well running car. No change.
I started to fiddle with the FPR yesterday, and no sooner then I touched it did it start leaking fuel around the o-ring...shit.
One thing led to another and before I knew it I had the upper and lower manifolds removed along with the fuel rail. A simple attempt at diagnosis has turned into a slew of while I am there maintenance.
I am going to:
Replace upper and lower manifold gaskets.
New FPR and associated o-rings
Send out my injectors for a complete service, ultrasonic cleaning and flow matching.
Replace all rubber fuel line in the engine bay with new metric fuel line and OEM clamps.
Bead blast and paint upper and lower manifolds.
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Yeah, I have swapped out the coil pack with one from a perfectly well running car. No change.
I started to fiddle with the FPR yesterday, and no sooner then I touched it did it start leaking fuel around the o-ring...shit.
One thing led to another and before I knew it I had the upper and lower manifolds removed along with the fuel rail. A simple attempt at diagnosis has turned into a slew of while I am there maintenance.
I am going to:
Replace upper and lower manifold gaskets.
New FPR and associated o-rings
Send out my injectors for a complete service, ultrasonic cleaning and flow matching.
Replace all rubber fuel line in the engine bay with new metric fuel line and OEM clamps.
Bead blast and paint upper and lower manifolds.
I know that you'll keep us informed ;)