excessive popping in exhaust at idle?

[bearster18]

This thing has what sounds like a misfire sitting at idle and only at idle. If driving down the road it drives smooth as silk. It's always kinda done it a little but since I installed the s/c, bigger injs, tr6 plugs, ect its gotten far more noticeable. No misfire codes or anything have come up either. Just makes my car sounds like *** sitting there idling. Anyone else run into this issue?

Factory coils with ford plug wires and tr6 plugs is the ign system. My tuner said he's had a few other 96-98 cobras do the same thing without issue. What do you guys think?

 

[bumsoil]

Mine does something similar. Kinda of a stumble with a plop noise. Real quiet.

 

[bearster18]

mines way to noticeable to everyone around me. lol Just seems kinda weird to me

 

[laddanator]

Mine pops also and I have a supercharger. Not sure why but it always has?

 

[Sn8kebitten]

Can you make a video? I've always kinda noticed it in mine as well. Never has had any other ignition problems throughout the rpm range. I do remember a buddy of mine saying that cars always idle slightly differently after installing a turbo or supercharger for some reason

 

[RPM4DAZ]

It seems that all modular engines have a distinct off beat sound/note at idle. Mostly from the right side. I think it is from the extra timing between cylinder three and four in the firing order. Now if the car sounds like a real slight miss or pop at idle, it could be a burnt exhaust valve or an exhaust valve not fully seating and seal properly. It could be spotted in a compression or leak down test. It probably won't cause to much of a problem for now, but could cause some damage down the road. Good Luck and keep us updated...

 

[bearster18]

I'll try to get a video tonight after I finish up the intercooler install. Like it'll affect the idling of the veh and drop rpm a bit as it does it. Then will settle back down and hold steady idle. It's always had it since I can remember but after the s/c install much more drastic. I get a dyno tune next week so maybe I can have them datalog it and possibly find a more precise area for it.

 

[CzchMex]

Have you checked your spark plugs? If they are dirty or old they can cause that. It doesn't fire enough causing un-burned fuel to burn off completely as it's exiting the valve and traveling into the exhaust. What you hear is the pressure change from that burn off in the exhaust.

 

[bearster18]

That makes sense too, but the plugs are new (maybe 600 miles on them). I may pull them and check it out just in case too.

 

[ImThatGuy]

My cobra does it to, especially on a nice cold start. This was after my motor was built. Then it smooths out! I cleaned my MAF and it helped a little bit. Doesnt affect my performance at all. I would like to know as well.

 

[97snakebite]

my car also misses or sounds like it misses when i cold start.. after about 1-2 min of idle it goes to normal.. must be a b head thing

 

[J&JIndustrial]

My 97 cobra kenne bell does the same thing at idle then idle goes to around 1k Rpms and smooths out don't really like it that much changed plugs still there

 

[03Steve]

Base fuel table cold sounds like it is causing havoc on you LLXx guys. Lean popping perhaps. Ask your tuner...

 

[Bdubbs]

Mine makes a very noticeable popping sound at idle. My tuner said it's the tight gap on my spark plugs causing the popping sound at idle. He said it's no big deal. I have TR6's gapped at .028

 

[Prototype007]

My current 97 Cobra does this and it's stock other than SVO/Borla side exits, but the old one didn't and it had flows dumped before the rear axle (very loud).