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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E36 (1991 - 1999)

E36 (1991 - 1999)
The E36 chassis 3-Series BMW was a huge hit among driving enthusiasts from the first moment the car hit the pavement. The E36 won numerous awards over the years it was produced and is still a favorite of many BMW enthusiasts to this day! -- View the E36 Wiki

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  #1  
Old 09-27-2011, 12:25 AM
puttitat puttitat is offline
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Mein Auto: E36 Coupe
1992 E36 325i - Rough idle at all times. Hesitates when cold.

Hi,

I've got an issue with erratic idle on my E36 325i Coupé Non-VANOS.



It's not really the classic 400-1000 rpm surge, it's just erratic, sounds as if cams are swapped.

Tried disconnecting O2 sensor. No go.
Tried disconnecting TPS sensor. No go.
Tried disconnecting water temperature sensor (blue). No go.
Tried disconnecting MAF. No go.
Tried disconnecting IAT sensor. No go.
Tried another ECU. No go.
Tried another MAF. No go.
Fitted new rubber boot. No go.

Haven't checked the ICV as it's not surging as much as just being erratic.

It idles poorly at all times, when cold it surges a bit from 7-800 rpm in "jumps", and the engine hesitates while driving. Seems "nervous" in its running. After approx. 4 miles, the hesitation disappears as fog to the sun (litterally from one second to another!), and all is well - except for the rough idle as told above.

If I start the engine when it's hot, and drive, the hesitation is not present. It's only when driving for the first few miles after a cold start in the morning.



SOLVED!!!!!! CPS was the culprit.

Last edited by puttitat; 09-27-2011 at 07:23 AM. Reason: SOLVED
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  #2  
Old 09-27-2011, 04:31 AM
granlund granlund is offline
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Mein Auto: -02 530 & -92 325is
Try checking the color of the spark plugs if the engine is running lean or rich. Pictures would be good.

Do you have any cam chain noise? I wonder if the upper tensioner (between the intake- and exhaust cams) might cause this?

Last edited by granlund; 09-27-2011 at 04:34 AM.
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  #3  
Old 09-27-2011, 05:45 AM
puttitat puttitat is offline
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Quote:
Originally Posted by granlund View Post
Try checking the color of the spark plugs if the engine is running lean or rich. Pictures would be good.

Do you have any cam chain noise? I wonder if the upper tensioner (between the intake- and exhaust cams) might cause this?
They are very light brown. A bit lighter than a fresh-from-tab 10w/60. Uhmmm :-)
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  #4  
Old 09-27-2011, 05:50 AM
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BMR_LVR BMR_LVR is offline
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How long has it been since you changed the plugs and coils? It may just need a good tune up.

Steve
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It's Deja Poo - as in, I've heard this **** before.
Steve

Calypso Red 1992 525i with 200K miles

1991 735i - Sold
1992 525i - Sold
1995 325is - Sold
2000 528i - Sold

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  #5  
Old 09-27-2011, 06:15 AM
puttitat puttitat is offline
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Originally Posted by BMR_LVR View Post
How long has it been since you changed the plugs and coils? It may just need a good tune up.

Steve
Coils have done 50000 miles, plugs was changed today.
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  #6  
Old 09-27-2011, 06:35 AM
granlund granlund is offline
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50,000 miles ago (80,000 km), did you replace the coil rubber boots too?
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  #7  
Old 09-27-2011, 06:39 AM
puttitat puttitat is offline
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Originally Posted by granlund View Post
50,000 miles ago (80,000 km), did you replace the coil rubber boots too?
Yeah, it was 6 brand new BOSCH complete with boots. Ground connections from valve cover to coils are also intact.

New CPS will arrive later today.
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  #8  
Old 09-27-2011, 07:03 AM
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BMR_LVR BMR_LVR is offline
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Good luck. I don't think that the problem is the CPS, but it would not hurt to have a new one as they can crap out on you at the worst of times.

Let us know if you find a solution to the problem.

Steve
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Most problems are usually something simple !

Quote:
Originally Posted by noego View Post
It's Deja Poo - as in, I've heard this **** before.
Steve

Calypso Red 1992 525i with 200K miles

1991 735i - Sold
1992 525i - Sold
1995 325is - Sold
2000 528i - Sold

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  #9  
Old 09-27-2011, 07:23 AM
puttitat puttitat is offline
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CPS was the culprit. New CPS and voila :-)
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  #10  
Old 09-27-2011, 07:36 AM
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BMR_LVR BMR_LVR is offline
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Congrats. I was under the impression that a bad CPS basically caused the car to just not run at all. I learn something new everyday. Thanks for sharing the solution.

Steve

BTW, would you be kind enough to check the resistance on the failed CPS? I would be curious to know what the reading was. If it is in the normal range (540 ohms +/- 10%), then that makes the resistance check rather unreliable for establising the health of the CPS.
__________________
Most problems are usually something simple !

Quote:
Originally Posted by noego View Post
It's Deja Poo - as in, I've heard this **** before.
Steve

Calypso Red 1992 525i with 200K miles

1991 735i - Sold
1992 525i - Sold
1995 325is - Sold
2000 528i - Sold

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  #11  
Old 09-27-2011, 12:23 PM
puttitat puttitat is offline
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Quote:
Originally Posted by BMR_LVR View Post
Congrats. I was under the impression that a bad CPS basically caused the car to just not run at all. I learn something new everyday. Thanks for sharing the solution.

Steve

BTW, would you be kind enough to check the resistance on the failed CPS? I would be curious to know what the reading was. If it is in the normal range (540 ohms +/- 10%), then that makes the resistance check rather unreliable for establising the health of the CPS.
Just for the fun of it I tried firing up without CPS connected. Ran fine.

The resistance is 728 ohms. Not that my measuring device is the most accurate in the world, but it draws a picture, that the resistance is too high.
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  #12  
Old 09-27-2011, 02:54 PM
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BMR_LVR BMR_LVR is offline
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Umm ...... the car cannot run if the CPS (crankshaft position sensor) is not connected ... unless I am just totally off my rocker

Not sure what you disconnected, but I would track it down to figure it out.

Gald you got it running though.

Steve

Edit: Are you referring to the camshaft position sensor? The car will crank and idle fine if it is disconnected, but it doesn't do well going down the road from what I understand.
__________________
Most problems are usually something simple !

Quote:
Originally Posted by noego View Post
It's Deja Poo - as in, I've heard this **** before.
Steve

Calypso Red 1992 525i with 200K miles

1991 735i - Sold
1992 525i - Sold
1995 325is - Sold
2000 528i - Sold


Last edited by BMR_LVR; 09-27-2011 at 02:58 PM.
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  #13  
Old 09-27-2011, 06:35 PM
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drivinfaster drivinfaster is offline
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cpk, ckp= crank position sensor, cmp/cmps=camshaft in tech acronym jargon.

i get confuseded sometimes myself, so i look for the 'm' or 'k'. cam will be designated by the 'm', the crank by the 'k'.

and no, the car will not start without the crank signal. it will run poorly, though, if one if out of spec.

the cam position sensor is just for a synch signal to identify the #1 cylinder.

thanks for the update on this though. it'll help wihen others may be searching for answers to similar issues.



df
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  #14  
Old 09-27-2011, 11:01 PM
puttitat puttitat is offline
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Quote:
Originally Posted by BMR_LVR View Post
Edit: Are you referring to the camshaft position sensor? The car will crank and idle fine if it is disconnected, but it doesn't do well going down the road from what I understand.
Hah, yea, i was referring to the camshaft position sensor. My bad. Dunno if it shows from my profile, but english isn't exactly my native...

The car ran smooth without the cam sensor, no hickups or the like. It's fascinating how the M50 can run without most of the sensors, they're all there for fine tuning Congratulationswelldone BMW
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  #15  
Old 09-28-2011, 06:18 AM
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BMR_LVR BMR_LVR is offline
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Location: Asheboro, NC
 
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Gotcha. Glad you were able to figure it out and get it running. I agree that it's odd that you can have a bad sensor (camshaft position sensor) and the car runs poorly, but you can disconnect that very same sensor, and the car runs fine. I gues the quesiton is, how would it have run on the road without the sensor connected. I wouldn't try it though.

Anyway, glad you got it fixed and thanks for sharing the cause.

Steve

P.S.: What is the resistance on the new camshaft position sensor? Maybe that can give us all a baseline to work off of since Bentley left it out.
__________________
Most problems are usually something simple !

Quote:
Originally Posted by noego View Post
It's Deja Poo - as in, I've heard this **** before.
Steve

Calypso Red 1992 525i with 200K miles

1991 735i - Sold
1992 525i - Sold
1995 325is - Sold
2000 528i - Sold


Last edited by BMR_LVR; 09-28-2011 at 06:19 AM.
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  #16  
Old 09-28-2011, 08:11 AM
puttitat puttitat is offline
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Quote:
Originally Posted by BMR_LVR View Post
Gotcha. Glad you were able to figure it out and get it running. I agree that it's odd that you can have a bad sensor (camshaft position sensor) and the car runs poorly, but you can disconnect that very same sensor, and the car runs fine. I gues the quesiton is, how would it have run on the road without the sensor connected. I wouldn't try it though.

Anyway, glad you got it fixed and thanks for sharing the cause.

Steve

P.S.: What is the resistance on the new camshaft position sensor? Maybe that can give us all a baseline to work off of since Bentley left it out.
The new position sensor measures 1244 ohm. My local parts shop states that the value should be 1400 +/- 10%. A bit out of range, but works just perfectly.

Crankshaft sensors on the other hand should measure 550 ohm +/- 10%.

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  #17  
Old 09-28-2011, 05:46 PM
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drivinfaster drivinfaster is offline
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^ sorry, i only speak cheese danish...


df
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  #18  
Old 09-28-2011, 10:54 PM
puttitat puttitat is offline
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^ sorry, i only speak cheese danish...


df
Problem solved



Figured you'd see the "Modstand [ohm] 1400" Modstand = resistance.
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