Is my MAF sensor going bad?

[car_guy81]

I'm fairly new to S4s. I've been modifying cars my whole life, and finally had the opportunity to buy an S4 from a friend. It's a 2000 with an AWE Stage 3 kit with the fueling upgrade. It has the AWE MAF housing and Hitachi MAF sensor. The previous owner had been chasing a mysterious hesitation and it was beginning to stumble on cold start. I found that it had a few boost leaks, and now that I've fixed those the car seems to be running great once it's warmed up. It is still plagued with the cold start stumble however. It has now become more of a, will barely run when it's first started stumble. I know that he replaced all the spark plugs and coil packs trying to diagnose it and I replaced both ICMs and fixed the boost leaks.

I believe I have it narrowed down to the MAF sensor. I have done my research and I know at idle it should read around 5 g/sec, but what about right at startup? For about the first 30 seconds (when it runs like crap) it is reading around 15 and then it drops to around 5. After that it runs smooth at idle, but if I give it some gas it will still stumble (the spikes in the graph are me giving it gas) until it has warmed up for a few minutes. I am attaching a log with the misfires and MAF reading, along with lambda. I wasn't sure what I should be logging, but I think you can get the point of what's going on. At around 90 seconds I turned the car off and turned it back on. That's why the misfire count goes back down to zero and you can see it doesn't misfire again.

Any help would be appreciated. I think I'm about to order a new MAF...

[BlkdoutS4]

Scan the car for codes

[car_guy81]

When I got the car it had a general misfire code. I cleared it when I fixed all the boost leaks and it hasn't thrown another code since.

[BlkdoutS4]

have you tried cleaning the MAF with some MAF cleaner?

[car_guy81]

Sorry, I forgot to mention that. I did take out the MAF sensor and spray it with electrical cleaner. It didn't look dirty at all, but I went ahead ans sprayed it off anyway.

[BlkdoutS4]

Sorry, I forgot to mention that. I did take out the MAF sensor and spray it with electrical cleaner. It didn't look dirty at all, but I went ahead ans sprayed it off anyway.

I would be careful, i've heard that you need to use MAF specific cleaner but I could be wrong.

[ljones125]

Seems like you have pretty good evidence its your MAF, but I was having a cold start issue due too my valve cover gasket leaking onto my coils, once the car warmed up it wasn't a problem but when I would first start the car it would almost always stall. Just throwing my 2 cents out there, good luck!