Chasing M42 Demons... what is wrong with this thing?~!!

[ReallyDirtyThirty]

Alright, since we last talked here is what has been replaced:

1. Fuel Filter
2. Spark Plugs
3. Air Filter
4. AFM
5. Throttle Position Switch
6. Oxygen Sensor

Car idles well once it is warmed up. Car is slow to start when cold, but otherwise runs fine. No major misfires or anything. However, when I stomp on the gas pedal the revs hold on the engine, the car tries to lurch forward (similar to slipping automatic transmission; my car is a 5 speed) and won't accelerate. It appears to bog down or lose power if the gas pedal is pressed to far while the car is under load. It would also lose power and get bogged down when it was going up hills on I-64 in West Virginia last weekend. Not fun! In neutral the engine will rev to redline just fine. After installing all of the above components the battery was disconnected each time to allow the ECU to reset and adjust to the new sensors. What the hell is going on with this car?

Thanks guys.

P.S. M42 Club seems to not be allowing me to join. If anyone knows the moderators could you please see if they could push me through. I tried to sign-up with the same name I have here. Thanks again.

[KenC]

Have you tried swapping in a known good ECU?

[crazyman]

Alright, since we last talked here is what has been replaced:

1. Fuel Filter
2. Spark Plugs
3. Air Filter
4. AFM
5. Throttle Position Switch
6. Oxygen Sensor

Car idles well once it is warmed up. Car is slow to start when cold, but otherwise runs fine. No major misfires or anything. However, when I stomp on the gas pedal the revs hold on the engine, the car tries to lurch forward (similar to slipping automatic transmission; my car is a 5 speed) and won't accelerate. It appears to bog down or lose power if the gas pedal is pressed to far while the car is under load. It would also lose power and get bogged down when it was going up hills on I-64 in West Virginia last weekend. Not fun! In neutral the engine will rev to redline just fine. After installing all of the above components the battery was disconnected each time to allow the ECU to reset and adjust to the new sensors. What the hell is going on with this car?

Thanks guys.

P.S. M42 Club seems to not be allowing me to join. If anyone knows the moderators could you please see if they could push me through. I tried to sign-up with the same name I have here. Thanks again.

I don't own an m42 yet (doing swap here soon). In my first BMW I was having the same issue, all I did was replace the fuel pump (the one that's on the frame) along with the fuel pressure regulator. I also took apart the fuel rail and cleaned up the injectors and ran a crap load of fuel injector cleaner for good measure. When I stated it up, it took off like a raped ape. Hope this works for you.

p.s. it also helped mine a little idle a little better when it was cold out.

[trackjunkie21]

sounds like a low fuel pressure problem. check your fuel pump and fpr.

[Dj Buttchug]

yeaa im gonna say fuel delivery issue...

[e30pq]

Sounds like the issue we just had with dirty fuel injectors

[gearheadE30]

^^ That would be my guess as well, or a clogged fuel line or FPR or something. Fuel pumps, in my experience at least, usually either work well or don't work at all, or maybe work intermittently. It sounds like when you open the throttle all the way, the engine gets a lot of air but can't supply enough fuel, so it doesn't accelerate, and probably surges to some degree. Revving in neutral wouldn't have necessarily the same symptoms because the engine doesn't have all that much inertia; it doesn't take much time or fuel to rev it, so you wouldn't notice the mixture leaning out.

[fiftytakedowns]

crank position sensor. It cuts fuel and spark when It gets an erratic signal. there is an element inside that warms up and expands, causing it to read more accurately, when they are old. the element goes bad.