Car can't drive when cold. only once warmed up. Misfiring when Warm....

[fiftytakedowns]

I gotta say, you are turning me against going to the COP conversion...

the m42 coils are just as bad perhaps. I dont even know if it is the coils.

I think Ive narrowed down the problem of the mid RPM misfire and bucking to be an ECU issue, however, The Cold Start Bogging Is still driving me crazy. I have to wait 15 minutes just for the car to warm up in order to drive it.



I pulled the plugs and replaced them with some champion plugs. not the best brand, but I dont want to throw money on a second set of plugs when my old NGKS have less than 10K on them.

anyone think the thermostat would cause the problem of cold starting?

[fiftytakedowns]

Ive got a bit of an update for today.

Drove the car around today after bleeding the system the proper way (from the bentley), and to my surprise the problem is almost gone. I think it is more of an ECU issue at this point because I have three ECU's:

mine stock:
Would Drive and pull normal, but for some reason if you downshifted or started cruising at 3.5 RPMs and then punched it it would misfire or hesitate etc. but it would Drive through it completely normal, and would pull through it as well.

mine chipped
same symptoms, except it would be at 4k RPms, and had more difficulty pulling through it. (still pulling a 1244)

Ryans stock: couldnt get problems to arise.

[fiftytakedowns]

so today I double checked TDC with cams and crank. found notch on pulley etc. etc.

replaced cracked intake boot.
replaced main relay
(both with brand new OEM)

I also took off the crank damper, impacted the mother on and then put on the extra pulleys. I was hoping this would eliminate a vibration that possibly might occur causing screwy CPS signals. just precaution.

I didnt really get a chance to drive it because It kept on wanting to overheat after I put the radiator back in. so I am letting it sit over night, then I will run the car in teh morning with the rad cap off to bleed out the air.


One last thing. There is a temperature sender on the right side of the radiator with a Plug that goes into it a three pronged one. my actual prong holder broke, so all I have is the three wires, and I dont know which wire goes to the respective prong in the plug, so if someone can take a picture of that for me or make a diagram that would be greatly appreciated as I have had that unplugged.

[fiftytakedowns]

the car cant start without the Crank position sensor? you really think that could be the culprit? I have 2 of them that I have been switching between hard to believe that both my spares are bad.

[RoadWarrior]

I think its the crank positioning sensor. if it was bad it would still not work when unplugged.And we had this exact problem on one of our work trucks.

[fiftytakedowns]

How can I test wiring, I have no IDea how to troubleshoot this way.

Where do I start?
Is it possible that some sensors can be bad even though they tested (resistance) okay?

[Ryann]

Seems like you've ruled out engine management components. You're down to wiring and mechanical issues.

[fiftytakedowns]

So today I did a sensor test by

driving car.
unplug sensor
drive again.
evaluate.
repeat.

I did that for every sensor:
Camshaft position
AFM
TPS
TPS and ICV
ICV
O2


Every single time it had the same symptoms.
also every time the car would run alright until about a minute or two of driving, then the misfiring would happen.

[fiftytakedowns]

False alarm.

Tried driving it today, No luck. I wonder why this is happening. I dont want to start buying parts and throwing them at the car.

[Ryann]

I thought you tested the TPS.

[fiftytakedowns]

I thineqrera

[fiftytakedowns]

BMW dealer could probably figure it out

aren't they going to charge an arm and a leg? I hate to be frugal, but I have to pay next months rent.

[b*saint]

BMW dealer could probably figure it out

[trackjunkie21]

Did you check fuel pressure whilst you were driving? This sounds alot like a fuel pump running out of steam.

[fiftytakedowns]

Do it. Yank the valve cover, verify cam timing. Verify even compression numbers. Locate any vacuum leaks and fix them. Verify good spark at every plug. Verify fuel pressure during the conditions of symtoms..

Im seriously depressed about this. I have checked cam timing like 4 times, Fuel pressure stayed at 40 at idle 45 When It was revving.

Crank position sensor was at 650 Ohms
Cam Sensor was at like 1400 Ohms

and I have One more of each.

My TPS was showing 1.8 through 2.5 ohms at the connectors and. 1.8 ohms through 4.8 ohms at the sensor itself . (bentley instructed to check with the sensor harness connector off)
My Spare TPS showd 1.6-4.6 ohms .

I dont even know what to fucking do anymore. Im starting to lean towards the coils but I dont want to buy new ones