87 325i hesitates when it is cold

[the bob]

hello all,

I did some searching and I could not find what I need so I will just ask.
The car hesitates from idle when it is just started for a couple of minutes when loaded. Is this normal. It also takes a couple of seconds of turning over before it starts. Now it is not bad but this is my first BMW and first real experience with fuel injection (previous diesel lover)

What I have done was plenty of sea foam. New cap and rotor and plugs, cleaned out the ICV, and tightened down the idle bypass screw on the AFS. I have about 17 inches of vacuum at the manifold.

Does it seem likely that it could be an oxygen sensor (That may have never been changed and car has 183K), possible coolant temp sensor (IT seems to ohm test within range), Tired AFS and/or AFS temp sensor.

Could it be just in need of a valve adjustment.
I did change out the air filter with a k&N.

When warm she really motors I just wonder if she is really alot faster of a car and I just dont know it yet. I am used to MB diesels.

May it be a fuel pressure modulator and how do you test for that.


Thanks so much.

I look forward to helping everyone once I figure this car out.


bob

[KenC]

What about the Fuel Pressure Regulartor?

[the bob]

Does it have anything to due with vehicle performance. I read is a previous post that it might . I am not sure how to test it or what to expect if it is not working up to spec.

I am temped to buy a new oxygen sensor, pressure regulator, and temp sensor but would like to avoid the unnecessary expense.

Thanks

bob

[KenC]

My car would hesitate upon light accel, and then I replaced the FPR and there is zero hesitation now. I'm not sure how you'd go about testing it though.
I bought a used one for $10.

[EverWiser]

It should not be the O2 sensor because it doesn't really begin controlling the air/fuel ratio until it has warmed up...I know that the BMW O2 sensors are heated but I doubt they reach the necessary operating temp in the first 2 or 3 minutes of running. More likely it's a vacuum issue or fuel delivery issue since the car is basically operating in "open-loop" mode. After warmup it sounds like your problem goes away which tells me that your O2 sensor is correcting for the issue that's giving you the "cold" problem. Good Luck!

[UNHCLL]

normal.
nature of 16 year old throttle body, injection, AFM's.

The cold-start bucking is just there to spill your nice hot coffee on your lap and start your day off with a bang.

[the bob]

Thanks for all the quick replies.

I wish that I had a friend local that I could switch one out with but not yet.

I will at some time visit a junk yard and may pull one out to see.


I have a feeling that it may be normal and not much of a problem but I am relentless and this kind of stuff as many of you are probalbly too.

thanks


bob

[the bob]

It must have been, at least somewhat related, to the o2 sensor. I changed it out with the cheaper mustang one with a lttle wire work and yeah baby no hesitation when she is cold. I am happy as hell with this little car I love how this car moves on the highway.


Thanks again.


bob