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Discussion Starter · #1 ·
Needs some help diganosing: 2001 330i 5 speed: 135K Miles
Symptoms:
Codes P071 P074 Both banks lean fuel triggered
Note CEL goes out by itself, and comes back on a few days later
While driving I am experiencing the following:This is an intermittent Problem
What feels like I have suddenly removed my foot from the accelerator only I have not..
Momentary Loss of power/no throttle response at all
This lasts for about 2-6 seconds (length varies) and re enguages power, accelrator control returns to normal...
Almost feels like cruise control as it adjusts speed back/although cruise is off
or like a limiter has been tripped..Only I am only turning abour 2-3K RPMs
Engine does not stall
RPMs do not climb or fall rapidly
Analog miles per gallon guage on dash pegs to max 50 MPG
So car thinks its not getting gas, but it is (rpms remain somewhat constant)

At first I thought the clutch was slipping however wouldnt the rpms just climb rapidly ? Which they do not. Also when not in this mode the car drives fine..Accelrates fine, compression seems fine...clutch enguagement seems fine

having the mileage it does (135K) I didnt mind spending some money on some parts that were long over due anyway so the folowing has been done very recently:
Fuel:
New fuel pump
New Fuel filter

Air:
New Air filter
New dip stick o rings
New Intake hose (Y hose which I found a hole in on undersie of hose Y hose)
Cleaned DISA, replaced with new gasket
Cleaned throttle body area with throttle body spray

I have not changed the coils on this car. However to produce a total unrepsonsiveness like this I would think that a single coil failure would only result in a missfire not a total power loss.....

Would a camshaft position sensor cause an issue like this ?
(Although no codes for this have been trigered)

Would a failing O2 sensor cause this ? No code triggrered specifically for 02 ...

Looking for some ideas....
This is my daughters car...And I traded her my ZHP as she lives far from me at school and I didnt want her driving this car...Rather solve it here at home and trade her back....(I miss my ZHP motivation to fix this quickly !!)

Any ideas very welcome...
Thanks Much ...Rob
 

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Hmm I don't know. Unlike most people you've provided plenty of information though. So bump for you!

Try getting the adaptations reset maybe. It could be an ECU issue.
 

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Discussion Starter · #4 ·
Yes correct I only have an Actron reader....Is there a home use GT1 or do I need a shop ?
I called a local (non dealer) but BMW shop to see what cost s for re flash...Says 1 hr labor at $80, does that sound resonable ?
 

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My guess would be a short in the oxygen sensor where one of the wires is grounding to the chassis. A bad crank angle sensor would also have these same characteristics. Make sure the connection/fuse to the fuel pump is good. There could be so many things... Take it to a mechanic who is good at diagnostics and has a good OBD scanner.
 

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OP, we have the exact same problem. I have done a lot more to my car than you have, and I still have these intermittent codes. My car runs fine and rarely does hesitate the way you described it, but I believe it is related to whatever is triggering these codes. Please refer to my thread a while back: http://forum.e46fanatics.com/showthread.php?t=894896

After doing all this work, I think my problem comes down to (with an educated guess on the probability of each):

1. Soft failing MAF (%35)
2. DISA (resealing just won't do, need a new one) (%35)
3. Subtle vacuum leak from either the intake manifold gasket, or the injector o-rings (%5)
4. Camshaft positions sensors (no codes though) (%25)

I am planning on addressing these issues soon.
 
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