Backfires/ throws cells after extended idle time

[318isbmw]

When I'm sitting in traffic and/ or slow driving around town with lots of stop time the car starts feeling bogged down and cell comes on. If I rev the and keep the idle around 1200 or so it will go away. Otherwise it'll backfire and will continue to lose rpm's until it dies, and if I try any throttle it backfires more. Its a 200k M50. I figure I'm not the only one to ever see this problem, so figured I would post up here before I dive into figuring it out.

[rpob5t]

sounds like a vacuum leak, check for cracked lines or at leat spray down the intake manifold with solvent and see if the RPM's pick up or smooth out to see if you have a bad intake gasket or injector o-ring; other than that happy hunting...

[Schwarz325]

Clean your idle air control valve or replace it and report back. Otherwise try and get the CEL read for codes. Good luck!

[318isbmw]

Clean your idle air control valve or replace it and report back. Otherwise try and get the CEL read for codes. Good luck!

The cell is gone by the time I can shut the car off. It pops up, and then I'll give it some throttle and it either backfires or goes away. Either way when I restart the car after backfiring and dieing, its gone. I'll try and clean the ICV this weekend and see how that goes. Anyone have any other ideas while I'm in there?

[e30s50dan]

sounds like 1 or 2 coils are bad ..had same trouble...ended up being 2 bad coil packs

[Adrian_Visser]

^^^^this^^^^

My car was doing the same thing, backfiring and slowly dying right as I was driving it back from the exhaust shop. Turns out I hadn't tightened the bolts on one of the coils. Find out which cylinder isn't firing by touching the exhaust manifold runners with a damp rag and seeing which one doesn't make steam when touched. Or you could be a man and just touch them quick with your finger, the one the doesn't feel slippery as your skin burns is the one that isn't firing.

Do the stomp test as well to see what CEL's you are getting.

[318isbmw]

^^^^this^^^^

My car was doing the same thing, backfiring and slowly dying right as I was driving it back from the exhaust shop. Turns out I hadn't tightened the bolts on one of the coils. Find out which cylinder isn't firing by touching the exhaust manifold runners with a damp rag and seeing which one doesn't make steam when touched. Or you could be a man and just touch them quick with your finger, the one the doesn't feel slippery as your skin burns is the one that isn't firing.

Do the stomp test as well to see what CEL's you are getting.

Good to know, this makes sense to me. Thanks guys! figured someone would have had the same experiences.