Popping noise at idle??

[Maz2001MP]

Does anyone know what might cause this?? Its a random popping (if I could make the sound it would sound like a low "dunk") that will accompany the regular tone of the exhaust. It's not loud or anything but actually very quiet except on a cold start where the sound is noticeable. I'm catless w/ a FMIC, full cs exhaust, bov recirc.

I just changed the plugs, wires and coil packs for a tune up a little while ago. I checked for exhaust leaks, nothing. I also just cleaned out the egr valve today and it seemed to have no affect. Would a possible leak in the recirc hose fitting cause this type of noise?

I have no CEL, but I was thinking possible exhaust (no ticking either) or intake mani leak? Vacuum is steady at 22-23hg. I still have yet to check my AFR's. I doubt this is a lean popping condition because I have no exhaust popping on decel but I am not sure. The power is there except for the basic MSP ecu bs. The turbo spools fine, I mean everything else seems ok, but the sound I am hearing is abnormal for sure.

 

[1moreMPH]

backfire. especially if you're catless. It's from running rich -- unburnt fuel mixed with the air comes out of the engine and goes through the exhaust. When it comes to the end canister and into the atmosphere it expands and pops, or can also partially ignite (im sure you've seen fireball videos on streetfire). That's a backfire, it's just from running rich. the pops at idle are when the o2 sensor is searching for the best a/f ratio and running rich-lean-rich-lean---, if you have a guage you can see this... but yea no worries, it's pretty normal, just may be running a bit rich. mine does this regularly and i have the Vibrant w/one hi-flow cat, but it did it even more when i had just the downpipe alone hooked up.

 

[Maz2001MP]

backfire. especially if you're catless. It's from running rich -- unburnt fuel mixed with the air comes out of the engine and goes through the exhaust. When it comes to the end canister and into the atmosphere it expands and pops, or can also partially ignite (im sure you've seen fireball videos on streetfire). That's a backfire, it's just from running rich. the pops at idle are when the o2 sensor is searching for the best a/f ratio and running rich-lean-rich-lean---, if you have a guage you can see this... but yea no worries, it's pretty normal, just may be running a bit rich. mine does this regularly and i have the Vibrant w/one hi-flow cat, but it did it even more when i had just the downpipe alone hooked up.

Thanks for the reply. I have yet to install my wideband.. Im getting lazy now lol well hopefully this weekend ill have time. If AFR's are out of wack, Il post up. Thanks again!

 

[1moreMPH]

i mean, they may not be perfect...but ive got a unichip on mine tuned relatively close to what i have, and it still backfires like a mother. you can usually see it on the guage though -- it'll be lean and then shoot over all the way rich real fast, and POW!

 

[Maz2001MP]

i mean, they may not be perfect...but ive got a unichip on mine tuned relatively close to what i have, and it still backfires like a mother. you can usually see it on the guage though -- it'll be lean and then shoot over all the way rich real fast, and POW!

I got ya, I dont mind the backfires while driving, I was just curious abou the random popping at idle that occurs.