Did a upgraded pulley on my 06 rev-up. 287 pully,600cc injectors, and retuned. Every 2 days or so my CEL comes on and then will go off. Code is a random misfire. This has been since i got it retuned, also when the car is hot and i turn it off the hot start is a problem too. Any ideas anyone? should i just go with that the tune wasn't 100%. Please if anyone can give me some input..... thxs!!!!!!!!!!

 

What tune you running? What plugs you running? The hot start issues are definitely tune related though, the tuner didn't set the trims properly which may or may not be related to your CEL...

 

running osirus and the plugs i'm not a 100% but there ngk platnum 1 step colder

 

I assume you don't have a wideband? I'd be curious to see what you're A/F looks like. You should also be able to feel and hear a misfire that is frequent enough to throw a CEL. How is drivability compared to before? Smooth, rough?

 

i do have a wideband.and yes you would think you would hear or feel the misfire but only some times ill notice it. Drivability seems ok. What would you want me to do with the wideband? how would i let you know what its doin?

 

Do you know how to read your wideband and what to look for? If you don't know what to look for it's a wasteful investment...

When under boost, you should be between 11 and 12, 11.5 is generally good. When out of boost / cruising or idle you should be between 14 and 15. In both cases it should be steady and not jumping around, even when moving the throttle in and out a bit.

I am willing to bet your trims and A/F is wacked out or jumping around which is why you're misfiring.

 

Very common problem on our boosted cars.

 

Tune needs fixing ... and change your plugs. Misfires are not usually due to afr problems but timing and/or spark issues (crank pos sensor, plugs, grounding problem etc). You will see your afr dip as a result of a misfire though (as unburnt fuel leaves the chamber).

 

yea it jumps around like crazy..... i cant even get a steady reading on it, ill have to drive it tomorrow to see were it is, but i think underboost its 11 11.5 12 it does jump all over tho.

 

This wasn't my understanding (when reading the AEM UEGO manual and some other stuff online). It mentions that burnt or not it doesn't change the reading on a wideband much. You would be correct however in the case of narrowband. I might be a dumb *** though.