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Author Topic: runs rough  (Read 2964 times)

waclawb

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runs rough
« on: November 20, 2011, 09:32:45 AM »
My well maintained e30 with M42 is having problems I can't figure out.
It died one day without warning on my way from work (100 miles daily commute) and I could not get it fire up again. Ended out towing it to my garage.
After troubleshooting I discovered that a culprit was bad crank sensor. Installed new one, and car starts again. But it doesn't run good anymore. Cold engine starts easily it would idle for a few minutes then dies, trowing an error code for a cam sensor (1510). Already replaced with a new one, but no change. When accelerating, engine backfires and chokes.
Already checked timing chain suspecting that it jumped, but it's all good and on markings. Tried spare ECU, air mass sensor, idle control valve, tested coolant temperature sending unit. Fixed all hoses under intake, to eliminate possible vacuum leaks.
What's next?
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DesktopDave

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runs rough
« Reply #1 on: November 21, 2011, 06:34:54 PM »
Test the resistance on both sensors.  Crank should be 580 ohms give or take.  Cam about 1280.  I've tested brand new sensors and failed them.  I suspect that the leads were bent too far during shipping and the internal suppressor jacket could be broken...that'd cause some trouble, for sure.
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waclawb

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runs rough
« Reply #2 on: November 21, 2011, 08:08:07 PM »
Already done this.
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waclawb

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runs rough
« Reply #3 on: December 10, 2011, 11:49:54 AM »
Still can't make it work right.
After replacing dead crank sensor car starts and runs smooth for about 10 min, until engine reaches normal operating temperature. Then it stalls.  Once restarted, it wouldn't accelerate, backfires. Car has completely no power. I can't think of the next step.
What I did so far:
1. replaced all the hoses under the intake to eliminate vacuum leaks
2. new spark plugs
3. new fuel pump and fuel pressure regulator
4. new cam sensor since I was getting cam sensor error
5. tested engine timing with light - it looks like goes back and forth with idle fluctuating about 200 rpm.
6. visual inspection of camshaft gears and timing chain - all looks OK to me, no wear detected.
7. tested compression and it's 180 on all four cylinders. Mechanically engine appears to be good shape. Runs quiet.

Any suggestions?
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