Author Topic: bad idle (Read 20479 times)

jrobie79 · « **Reply #30 on:** August 05, 2008, 10:59:03 PM »

Quote from: AcSchnitzer318is;54349

Car is in the shop... will keep everyone updated... pray it does not cost me an arm and a leg

yeah i hope its simple for your sake to keep cost down, if it gets fixed lemme know what the problem was. thanks

AcSchnitzer318is · « **Reply #31 on:** August 06, 2008, 12:29:54 PM »

LOL you guys owe me

Cost me $145 (2 hours of diagnosis). They smoke tested and found no vacuum leaks, did find 2 small exhaust leaks. No problems. Then they fuel pressure tested it 40 - 50psi. All is good there. So then it took them some time... I gave them my list of replaced parts, but they checked to make sure everything I replaced them with was good. No problems.

Problem turned out to be a factory service bulletin part. My motor that I bought did not have it... but it's an "amplification" pigtail harness that goes between the AFM and the circular connector that normally goes on the AFM. Seems BMW was having customers with production date 2/90-12/90 m42's come in with erratic idle problems and this was their solution to fix it. Part number is: 13 62 1 734 516. It is designed to amplify the signal from the potentiometer in the AFM to the DME control unit.

My results... car has not turned off on me yet on cold start. Idle is still a little erratic for a min or two but they said that was due to the cams I am running. They said they could adjust the timing if I wanted to try and smooth it out some more. I'm going to run it like this for a few weeks and see what happens. As a side benefit, my car was running lean according to the dyno I ran. Well now I feel like I picked up a few rwhp which I am attributing to the lean condition being fixed by the part possibly. It feels more peppy and fun. I want to have it dyno'd again now to see what it puts down.

Hope this helps you guys... let me know what your results are.

EN318isPDX · « **Reply #32 on:** August 06, 2008, 01:01:35 PM »

Quote from: AcSchnitzer318is;54438

LOL you guys owe me

Cost me $145 (2 hours of diagnosis). They smoke tested and found no vacuum leaks, did find 2 small exhaust leaks. No problems. Then they fuel pressure tested it 40 - 50psi. All is good there. So then it took them some time... I gave them my list of replaced parts, but they checked to make sure everything I replaced them with was good. No problems.

Problem turned out to be a factory service bulletin part. My motor that I bought did not have it... but it's an "amplification" pigtail harness that goes between the AFM and the circular connector that normally goes on the AFM. Seems BMW was having customers with production date 2/90-12/90 m42's come in with erratic idle problems and this was their solution to fix it. Part number is: 13 62 1 734 516. It is designed to amplify the signal from the potentiometer in the AFM to the DME control unit.

My results... car has not turned off on me yet on cold start. Idle is still a little erratic for a min or two but they said that was due to the cams I am running. They said they could adjust the timing if I wanted to try and smooth it out some more. I'm going to run it like this for a few weeks and see what happens. As a side benefit, my car was running lean according to the dyno I ran. Well now I feel like I picked up a few rwhp which I am attributing to the lean condition being fixed by the part possibly. It feels more peppy and fun. I want to have it dyno'd again now to see what it puts down.

Hope this helps you guys... let me know what your results are.

My car has this pigtail such "extension/amplifier" I have tried running my car with and without it and it doesn't really make a difference on my car it seems.. I'm not really have much idle issues anymore since i replaced my fuel system. I get a lil problem on cold start due to my coolant sensor (i believe)

Thanks for sharing your information.

jrobie79 · « **Reply #33 on:** August 06, 2008, 02:49:16 PM »

Quote from: AcSchnitzer318is;54438

LOL you guys owe me

Problem turned out to be a factory service bulletin part. My motor that I bought did not have it... but it's an "amplification" pigtail harness that goes between the AFM and the circular connector that normally goes on the AFM. Seems BMW was having customers with production date 2/90-12/90 m42's come in with erratic idle problems and this was their solution to fix it. Part number is: 13 62 1 734 516. It is designed to amplify the signal from the potentiometer in the AFM to the DME control unit.

i got an august 1990 prod date, so ill look into this, how much is this part?

AcSchnitzer318is · « **Reply #34 on:** August 06, 2008, 05:13:15 PM »

Quote from: jrobie79;54449

i got an august 1990 prod date, so ill look into this, how much is this part?

Don't know... The shop I go to gave it to me free. I've taken cars there for the last 10+ years. They just charged me for the 2 hours of diagnosis.

But... that didn't fix my problem. It started doing it again today just like before. They said to bring it back in tomorrow and they were going to pull the valve covers and check the timing. I have to take the cam specs and all that good stuff so they can do it.

While it's there I am going to have them weld the holes in the exhaust that are before the o2 sensor and then reset the computer to see if that's it. The only time it REALLY got better was when I put in the brand new o2 sensor so maybe the holes in the exhaust are causing some problems.

Will keep you guys updated.

colin86325 · « **Reply #35 on:** August 07, 2008, 06:45:30 PM »

That's very interesting about the pigtail for the AFM. Mine had this, but we removed it. Sometimes the idle is a bit lumpy, but it's sporadic. I'm going to reinstall it.

I think that the "amplifier pigtail" most likely contains an inline resistor--maybe for the air temp sensor or the potentiometer--to fool the ECU into adding a bit more fuel. If i had an extra pigtail it would be interesting to dissect it.

jrobie79 · « **Reply #36 on:** August 09, 2008, 10:16:05 AM »

anyone know how much these cost? and where i can get it from? aside from the dealer

jrobie79 · « **Reply #37 on:** August 12, 2008, 11:40:57 PM »

Quote from: jrobie79;54580

anyone know how much these cost? and where i can get it from? aside from the dealer

ttt

AcSchnitzer318is · « **Reply #38 on:** August 13, 2008, 12:07:16 AM »

^Best bet would be to try a junkyard I think. Or search the interwebs for the part number I posted.

On another note... I started a 150000+ mile 318is that does not have this problem. LOL now I know how smooth these things are supposed to be. Makes mine look like an all out race car on startup with it being so smooth and mine being so rough. We really need to figure this out guys. It's starting to haunt my dreams.

jrobie79 · « **Reply #39 on:** August 13, 2008, 07:25:02 PM »

if i can find another e30, im just gonna part mine out, the rust is getting to be a bitch and i really dont want to start welding in repairs on a 17 year old car, only to look at it in 3 months and see more rust. im moving to socal so ill look for one then. and this idle problem, ill live it with it for the next few months

achtungE30 · « **Reply #40 on:** August 17, 2008, 07:39:17 PM »

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

AcSchnitzer318is · « **Reply #41 on:** August 18, 2008, 12:14:04 AM »

Ya the list of sufferers continues to grow. I've made no progress on this yet. The shop i go to still wants to pull the cam cover and check the timing. I want to convert it to COP to see if that will help the problem any. As always, I'll keep you guys updated with progress, or lack thereof.

A couple of buddies suggested maybe a thermal time switch. Do our cars have one of those? That's the first I've heard of that particular part.

jrobie79 · « **Reply #42 on:** August 18, 2008, 11:01:45 PM »

no dice for me as well, gonna tackle the timing chain replacement soon, ill keep this thread updated with results.

AcSchnitzer318is · « **Reply #43 on:** August 21, 2008, 12:10:09 AM »

Ok guys... I got some new info that could help us narrow this problem down. I spoke to the previous (original) owner of the motor I bought for my car and he said he is 100% positive it didn't exhibit any hesitation/idling erratically behavior. Also I talked to the dealer I bought my CAR from and he said the original motor (240,000mi) did exhibit that behavior. So something that didn't get swapped in with the new motor is causing this. I swapped the ENTIRE motor & access. This means the only things it could be are:

exhaust (clogged cat?

)
vacuum lines to external systems (brakes, etc???)
coils
wires

Give me your insight gentlemen... I feel like this is a revelation that could help narrow this down.

EN318isPDX · « **Reply #44 on:** August 21, 2008, 10:42:47 AM »

Quote from: AcSchnitzer318is;55260

Ok guys... I got some new info that could help us narrow this problem down. I spoke to the previous (original) owner of the motor I bought for my car and he said he is 100% positive it didn't exhibit any hesitation/idling erratically behavior. Also I talked to the dealer I bought my CAR from and he said the original motor (240,000mi) did exhibit that behavior. So something that didn't get swapped in with the new motor is causing this. I swapped the ENTIRE motor & access. This means the only things it could be are:

exhaust (clogged cat?)
vacuum lines to external systems (brakes, etc???)
coils
wires

Give me your insight gentlemen... I feel like this is a revelation that could help narrow this down.

Coils maybe

Clogged cat is easy, go to an exhaust shop and ask them if ur cat is clogged. OR put your hand behind your exhaust and feel for good air flow.