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Registered User
Join Date: Nov 2006
Location: Akron, OH
Posts: 27
Cold start = Rough Idle, Misfires, Running Rich?!?!

I searched all of the rough start / bouncing idle / cold start / bogging threads...but my issue is unique & different (because it doesn't improve when engine warms up). Below are the basic symptoms & background...

'95 318is (M42, 5sp, 190.5k)

Note -- this car has NEVER had any bouncing / rough idle problems prior to tonight...

- cold start @ 0deg F resulted in bouncing/rough idle and serious had rock solid idle & no misfiring at anytime before this
- warming car up to operating temperature did not help problem at all
- no CEL or SES lights of any sort
- significant loss of power, car struggled to pull itself up to 30mph


So, it's gotten quite cold here the past few days. Two nights ago, it was 4F -- my '95 318is started up first try, with some effort, but it idled and drove away issues. That was just one night ago!

Tonight it actually hit zero degrees F! I started the car (cold start), and wasn't happy to be brought to life, but it started first try. I went back into the house while letting it warm up a bit. Not something I typically do but the girlfriend asked if I would since it was so cold out.

When I came back outside 5 mins later, the idle was bouncing between 500 - 1500 rpms, and it was missing BADLY!! NOTE -- this car has never had a bouncing idle before. Having said that...a dirty ICV probably wouldn't manifest itself during the 5mins I'm in the house, right?? Anyway, I decided to drive it around the block to see if the problem improved/disappeard when the engine gets up to temp.

I got the coolant temp pegged @ 12 o'clock, and it's still running horribly. It's missing badly (sounds like an old VW bug), and there is NO POWER whatsoever. It struggled through the RPM range as if I were towing another vehicle. It was an effort to get to 30mph!! I pulled the car into the garage and decided I was going to pull the (-) battery terminal and see if that helped. It hadn't thrown any codes but I though that perhaps it was 'confused' and on the wrong fuel map or something (OBD-I)

When I came back into the garage to reconnect the (-) terminal, it smelled strongly of fuel. It wasn't leaking from the car I was lead to believe that the car had been running very rich, possibly causing the misfires. But what would cause it to run so rich????

Again, this is somewhat unique in that things did NOT improve when it reached operating temperature.

My question is -- has anyone dealt with this before?? If so, what was the outcome?? I don't have the time/tools/facility to repair this, so the car is getting towed tomorrow, but I would like to know if someone has figured this problem out!!!

Any posts are appreciated, thank you for taking the time to help me out!!

Old 02-04-2007, 08:49 PM
  Pelican Parts Technical Article Directory    Reply With Quote #1 (permalink)
Registered User
Join Date: Nov 2006
Location: Akron, OH
Posts: 27
No improvement this morning -- car was towed.

Before it was towed, I did the "stomp test" and read out the stored codes (still OBD-I). I only got P1271 -- ignition coil fault. That leads me to believe that I probably lost my ignition coil, or that my plug wires have had it.

It stinks cause both of those are easy DIY's...but temps are below 0 here in NEOhio all this week, and I don't have the time to swap parts and make it run right again. So, sadly, I'll be paying someone else to do that for me.

I'll report back with what the final fix was.

Old 02-05-2007, 04:13 PM
  Pelican Parts Technical Article Directory    Reply With Quote #2 (permalink)
Junior Member
Join Date: Feb 2007
Location: hartsville sc
Posts: 4
Old 02-06-2007, 01:05 PM
  Pelican Parts Technical Article Directory    Reply With Quote #3 (permalink)
Registered User
Join Date: Nov 2006
Location: Akron, OH
Posts: 27
To close the loop on this problem....

The shop determined that my #1 ignition coil basically melted itself -- which caused the misfires and rough idle. They checked the plug wires and everything was ok there. The #1 spark plug is a little gunked up, but they suspect it will burn itself clean once the coil is replaced. They also got an O2 sensor fault when reading codes, but they think that is due to it running so rich for those few moments.

In attempting to track down the cause for the ignition coil catastrophe, they performed a "smoke test" on the intake system. They found air leaks in my intake boot and my lower ICV hose. They hypothesized that my leaky intake boot could've caused the car to run a "lean" mixture. At sub-zero temps, it requires a stronger spark to fire off a lean mixture. They think I basically "leaked spark" back into the coil itself, since there was so much resistance in the #1 cyl due to the lean condition. I basically melted the #1 coil

So, new ignition coil set, and replacing the leaky intake parts...hopefully all will be right again.

Old 02-07-2007, 06:44 AM
  Pelican Parts Technical Article Directory    Reply With Quote #4 (permalink)
Registered User
Join Date: Nov 2006
Location: Seattle, WA
Posts: 104
Could you (or someone) describe the "smoke test?"
David Frost
Formerly smitten by a 1993 325i Sport with 170K+ miles. Now infatuated with an Audi A3 2.0T DSG.
Old 02-07-2007, 08:29 AM
  Pelican Parts Technical Article Directory    Reply With Quote #5 (permalink)

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