M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => General Topics => Topic started by: feunfer on August 29, 2012, 08:47:39 PM

Title: 1991 318is idle issue (M42)
Post by: feunfer on August 29, 2012, 08:47:39 PM

The M42 has developed an idle issue recently.  It was checked for vacuum leaks (resolved), all hoses OK and ICV was replaced with new at suggestion of a more knowledgeable friend.  Still idle is not great, car stalls on initial start-up, but after the car warms up a few minutes it's just fine.

My shop swapped out the AFM from another car and it seems that may have helped, but these are apparently hard to come by and the dealer wants over $600 for one.

BMW part number is 13 62 7 558 785
Bosch number is 0280 202 134

Does anyone know where one of these can be purchased?

Thanks...

Title: 1991 318is idle issue (M42)
Post by: tfrain on August 30, 2012, 03:16:52 PM

is this from a HOT start, or does it not matter - it does the same hot or cold?

Title: 1991 318is idle issue (M42)
Post by: bmwman91 on August 30, 2012, 05:29:32 PM

I find it unlikely that the AFM is the issue. Look around on eBay or on the forums. You should be able to get a good used one for under $100, if you are convinced that the AFM is the problem.

How did you test for vacuum leaks? You may still have one.

Title: 1991 318is idle issue (M42)
Post by: 5m1dy on August 30, 2012, 07:48:29 PM

Check your plugs. My m42's not tuned properly yet and occasionally it dumps a whole lot of fuel when it stalls/is turned off and the plugs have been getting wet, meaning that it struggles to start and won't idle.

Title: 91 318is idle issue (M42)
Post by: feunfer on August 30, 2012, 09:21:29 PM

Thanks for your reposes.

It was from cold start.  If the engine is warm there is no problem.

I will have the shop check for more leaks.  I don't want to change the AFM if I don't need to.

Plugs... nothing has been done.  Will have that checked out.  Is there any plug that is recommended?

Any other issues to look for?  TPS?  

Again, Thanks

Title: 1991 318is idle issue (M42)
Post by: DesktopDave on August 31, 2012, 09:47:14 AM

Test the coolant temp and air intake temp sensors for proper specifications.  If they're reporting the wrong temp you'll have rough cold starting.

I've been using NGK plugs on my car, they've worked well for me in the past.