Hello!
I've searched everything I can think of with no results. My 86 camaro has a "popping" exhaust backfire at idle and a slight stumble above idle. When you first start the car it is barely there, happening every 20 seconds or so, but as soon as the car appears to enters closed loop its every 1-2 seconds. At 40% throttle to wot its gone (or not noticeable). I didn't notice any performance decrease except at low accelerations and idle.

Some additional info - brand new o2 today, IAC, tps, coolant temp sensors within 500 miles, maf cleaned less that 500 miles ago, new distributor within 2000 miles, new ignition module (not installed by me) and new ecu within 2000 miles. Plugs all look good, no wire arcing noted. Vehicle has hooker headers, no cats, and a cutout.

What could it be?!?! Clogged egr?! Am I missing something?

Thanks in advanced!!

 

Since you didn't list it... have you had the timing properly checked and set? Perhaps it wasn't set properly when you replaced the distributor?

 

EGR valve stuck open do to crud build up..? this would lean out a lot at idle so pops etc would be heard, but as you speed up this is less of a problem so you don't notice it.
just a thought.
good luck
M

 

I haven't had the timing checked again, midas installed the distributor..so I really shouldn't have a ton of faith it was set right..but I haven't checked..I'll have to do that. I'll also check the egr, thanks for the responses!! I'm totally lost on this one.

 

you might have a sticking valve? i think a vacuum gauge could help find the problem.

 

Thanks gents! I'll look into the egr and hopefully that's it. I was worried I had a dead cylinder but with it getting worse at different times I figure it has to be sensor related. Any possibility that a vaccum leak causes it? I'm sure that I'm due for all new lines but can't find em anywhere and don't really know how to test vacuum.

 

Any update on this? I'm having a similar problem.