popping under acceleration

[smount101]

I have a 2000 expy 5.4 4x4. Had an enging light, changed vaccuum hoses pcv hoses new plugs,fuel filter, coils, and all new sensors under the hood. Engine light is off but i still get a popping noise when accelerating or going up a hill. Almost feels like the engine is cutting out slightly. Any ideas? Would a plugged cat cause this and not throw an engine code? Cannot figure it out any help would be great, thanks!

 

[joezek]

Did they replace all coils? Was the coil replacement specifically because of this popping, or was that unrelated?

A lot of times popping through the intake can be caused by a timing chain that has "jumped" which throws your cam timing out of wack. Also a severe intake leak will cause popping. Is it popping through the intake or exhaust?

Without a check eng lite it's harder to troubleshoot. I think a plugged converter will give you a check eng lite.

 

[smount101]

popping

I replaced all coils trying to fix the popping sound. To me it feels like intake not exhaust. Almost like a misfire on one of the cylinders or something. Its driving me crazy. I forgot the tps and changed it today. No difference. Only does it under acceleration, and the no engine code doesnt help any.

 

[joezek]

When you changed them did they come with those short ignition leads? Are you positive that each lead is actually centered over each spark plug?

Did you clean your MAF sensor? If it gets dirty or gets some oil on it (like from a K&N Filter) then it'll make the engine run all screwy. I had a tiny little piece of a leaf from a tree that got sucked into my MAF sensor and the car (350Z) started sputtering and popping. It was fine at low rpm but couldn't get enough fuel at WOT. The leaf fooled the computer into thinking no air was moving across the MAF sensor.

 

[smount101]

I did clean the maf, no difference. Not sure what your talking about as far as the leads. My cp's just had a rubber boot with a spring inside and the other end was where it plugged in.

 

[Quevy50]

Mis-Fire

With all that you have done so far, it sounds like a timing issue. How many miles on the engine? I assume that you replaced the coils with new...right? I recently had a similar problem under load and replaced all 8 coils....problem solved. However, the miss never sounded or felt like it was coming back thru the intake. Typically, a back-fire thru the intake indicates a timing issue.