cam position sensor failure or maf? - The Unofficial BMW M5 Messageboard (m5board.com)

stanm5 · 19th April 2004, 21:56

Hi,
I'm wondering if anyone can describe the symptoms of cam position sensor failure and of fouled maf?
My car has developed a bit of hesitation at start and also when pulling through the power band. Additionally whe the car is first started in the morning it hesitates quite badly and will not rev past 3000.

It clears up after a few minutes. The car stays in doors at night so it's not really cold when I start it up.

Cheers,

gsfent · 19th April 2004, 22:08

Quote:

Originally Posted by stanm5

Hi,
I'm wondering if anyone can describe the symptoms of cam position sensor failure and of fouled maf?
My car has developed a bit of hesitation at start and also when pulling through the power band. Additionally whe the car is first started in the morning it hesitates quite badly and will not rev past 3000.

It clears up after a few minutes. The car stays in doors at night so it's not really cold when I start it up.

Cheers,

I just had the intake cam position sensor replaced on one bank over the weekend. I did not have your symptoms, in fact I had virtually no symptoms. In retrospect, the car is now more eager to pull, and it needs less throttle opening. I would suspect other than the CPS if my experience is typical. BTW, I didn't have any codes until last week, yet this must have been going on for some time as the change is noticeable.
Regards,
Jerry

Synergy · 19th April 2004, 22:27

Quote:

Originally Posted by stanm5

Hi,
I'm wondering if anyone can describe the symptoms of cam position sensor failure and of fouled maf?
My car has developed a bit of hesitation at start and also when pulling through the power band. Additionally whe the car is first started in the morning it hesitates quite badly and will not rev past 3000.

It clears up after a few minutes. The car stays in doors at night so it's not really cold when I start it up.

Cheers,

What a coincidence... I was just about to post a similar question.

For a few weeks now, my car has idled rough on a cold start. I had to keep the RPMs above 1500 for a couple of minutes, or else she would die on me. After she warmed up, she would drive just fine. She set off a check engine light just a little before she did it and when I took her into the dealer, they said it was the pulse flow sensor. Well, a couple of hundred dollars later, I picked her up and she still had the same idle issue, but no SES light. I decided to live with it for a little bit since I don't have a ton of money to dump into wild goose chasing with the dealer at the moment.

A couple of days ago, she started having a lot of trouble with a warm start, and also threw another SES light. Cold starts still just have a rough idle until she warms up. But if I turn her off and then turn the engine back on after about 10 or 15 minutes, she has some real issues. Her idle is a slow loping. There is absolutely no power. Pressing the gas pedal doesn't really do anything. I have to let her just sit and idle for about 5 minutes.

Anyone have any ideas? I'm taking her in tomorrow, but figured I'd ask and see if anyone might have encountered this before.

Ahmed · 20th April 2004, 02:06

3 possibilities!

1. MAF's are defective
2. Spark plugs and cables are defective
3. ECU (cold Start) parameter fault!

I dont know about US spec M5's, but do you get a message in your test display that says "engine failsafe prog" ??? If so, then your engine goes into safe mode and thats why you run rough and get power loss!

stanm5 · 20th April 2004, 04:26

I just finished cleaning both MAF's using detailed instructions from the archives (what a great resource)!
I took it out for a drive and after lettign the engine get up to operating temp. I attempted to make it hesitate. I would say that it's 95% better than before. The real test will come tomorrow once I've been in traffic for a while and the engine is really hot.
More on this tomorrow.
Cheers,

sforssell · 21st April 2004, 14:48

Has anyone tried to clean MAFs in a ultrasonic washer? The thing they use in laboratories to get equipment cleaned. It looks like a small bowl with water which vibrates ultrasonically.