i have an 01 s4 with apr software, straight pipe exhaust, new divertors, new plugs and coil packs. im getting a misfire under certain loads. what could be the culprit? mass air? car has 50xxx miles on it. runs very smooth under part throttle but misses randomly under hard throttle. code the other day said cylinder one. which one is cylinder one on this car?

 

cyl 1 is front pass side

 

MAF could be the culprit, but it will usually only cause a misfire code if it's causing variations in the idle. Usually under throttle, it will just run a little rich, but you'd otherwise not know that it was faulty.

I think it's more likely to be an ICM. They are notorious for causing misfires (especially random) along with coil packs.

 

check engine light just came on and stayed on this time. code was maf sensor

 

I think you have your answer.

If you clear codes, will the misfire codes come back reliably? If so, you can unplug your MAF and see if the codes still come back, not that you really need it but it will give you more assurance that the MAF is causing the misfires.

Also, try some MAF cleaner before you blow $175 on a new MAF

 

i guess you can rule out bad coilpacks. normally you can tell if you have bad coils if you pop the hood and theres just a potent odor of fuel.

 

it sounds like your MAF. if you have a bosch MAF, I have an extra one laying around i am trying to get rid of for dirt cheap. PM me.

 

i had same problem.. under small loads car drove fine.. when i got on it the misfire was obvious and drove me nuts.. cylinder number three... cracked spark plug.. so id go ahead and do some preventative maintenance and change plugs..see what happens... theres a chance you could have broken or cracked it upon installation..