Help Needed, M42, Cold Start Hesitation

[Spalding]

I have a 91, 318ic, with a 5spd. What does this problem sound like to you?

When I leave my car outside on a cold day it has some hesitation on a cold start. If I rev the engine it will hit 1000-1500 rpm and then it will start to stall, the revs will drop and it will idle as normal. As the car warms up the hesitation will move higher in the rpm band. Once the car is warms it drives as normal. It doesn't have this problem on a warm day or when left overnight in my heated parkade.

There are no issues starting the car and the fuel economy seems good. As mentioned the idle is normal. I get around 400km in the city and 500km on the highway.

Any thoughts on what my car needs to get rid of this annoying problem?

[Shocka]

not just cold start procedure? mine does it every morning. then its warm an its good, its also 10yrs older.

[Spalding]

No, this is not normal. My 87 325ic never had these problems and I can't believe our cars were this useless when new. I hate waiting for my car to warm up. Any suggestions?

[nuts4bmw]

Not being a professional mechanic, thiese symptoms sound to me like something is icing up in the induction system......just a suggestion though

art

[Slammed80]

not sure on the m42, but you could always check the Coolant temp sensor for the Computer. Almost sounds like its getting to much fuel when it's cold

[crunk3]

idle control valve?

[kowalski]

Originally Posted by crunk3 idle control valve?

i'm going to go with captain glow in the dark shoes on this one.

[redhatpat]

Test the temp senser then test/clean the icv.

[cameronR]

Buy miscellaneous sensors from my parts car....

http://vancouver.en.craigslist.ca/pts/917898994.html

Sorry shameless plug for myself.

[raisbeck]

Originally Posted by Spalding I have a 91, 318ic, with a 5spd. What does this problem sound like to you? When I leave my car outside on a cold day it has some hesitation on a cold start. If I rev the engine it will hit 1000-1500 rpm and then it will start to stall, the revs will drop and it will idle as normal. As the car warms up the hesitation will move higher in the rpm band. Once the car is warms it drives as normal. It doesn't have this problem on a warm day or when left overnight in my heated parkade. There are no issues starting the car and the fuel economy seems good. As mentioned the idle is normal. I get around 400km in the city and 500km on the highway. Any thoughts on what my car needs to get rid of this annoying problem?

Just curious. What did you finally figure out? I've had the same problem with my daughter's car for a year or so. I've changed out just about everything, and the car runs fine. It just takes a couple of miles at 1000 rpm before it does.

[Blackice]

Originally Posted by raisbeck Just curious. What did you finally figure out? I've had the same problem with my daughter's car for a year or so. I've changed out just about everything, and the car runs fine. It just takes a couple of miles at 1000 rpm before it does.

WOW, you are still having issues with this car..... Maybe start a new thread, lets start fresh and see if we can think of anything. I have a spare ECU now, maybe you could try that..... Did you check the fuel pressure ?

[raisbeck]

Originally Posted by Blackice WOW, you are still having issues with this car..... Maybe start a new thread, lets start fresh and see if we can think of anything. I have a spare ECU now, maybe you could try that..... Did you check the fuel pressure ?

Not sure how to start a new thread, and my daughter _can_ be pretty practical... if it involves losing her wheels. We've got a heated garage, and in normal weather it warms up enough by the time she gets to where she can go more than 30 mph, that she can run it up to 4500 without anyi hesitation.

Problem is that she now has a boyfriend that lives in a trailer park.
And its been 30 below for the last several weeks. Takes a bit more than 30 seconds to get it warm enough to run right. Like 4-5 minutes at an idle. Now she gets up 20 minutes earlier, starts the car and leaves it idling while she showers. I sorta figure that this is a good thing, as she's definitely part of the MySpace generation. If it takes more than 20 milliseconds, she's forgotten. This is Wyoming. You take care of your horse if you don't want to walk in the snow.

I've been browsing the 'net and studying the service manual and just basically daydreaming about it. More of a excersize in mental masturbation than anything practical, but I don't like anything that I don't understand. I'm about convinced that its got to be the ECU. I've replaced and/or checked the crank sensor, the cam sensor, all of the vacuum hoses, the wiring from the sensors to the firewall, the water temp sensor, all of the water hoses, the water pump, the air flow sensor and air temp sensor, the idle valve, the fuel pump (flow and pressure's ok despite the mileage), the throttle potentiometer, ... I'd have to ground her long enough open the hood and make a list. But, it still behaves the same.

I've been shopping for a new ECU. The car's not worth the price of a new one, and I'm not sure how to be sure that an Ebay special is solid. This seems to be a problem with a lot of older M42's, at least based on the 'net. But I haven't found a solution yet.

raisbeck@uwyo.edu