possible afm problem?

[bmwlover0725]

I've replaced everything you could possibly think of in the engine bay except for the afm. When I say everything, I mean everything. I even recently rebuilt the engine and compression is fine. Everything checks out good. I've got an air/fuel ratio gauge and it's telling me that I run lean most of the time. I have surging acceleration and a slightly rough idle. The idle gets even more rough upon turning on the A/C. I also haven't replaced the ECU yet, but I think it's the AFM. It's been adjusted several times and does nothing each time I adjust it. The fuel injectors are fine as well. My fuel filter is about 10k miles old and needs to be replaced, but I don't think it's so clogged that it's causing this much of a performance loss.

Can somebody help?

[slo325i]

Maybe try cleaning the afm with that spray cleaner??

Also spray some carb cleaner and scrub with qtips on in the ICV. It helped me with my idle issues a quite bit.

Good luck

Justin

[nando]

how lean is it running? if it's running more than about 15:1 at idle, it will idle roughly.. lean running can definitely make it surge on acceleration too.

[bmwlover0725]

it's running pretty lean. I know it's definitely running too lean. It also misfires slightly and will go fully lean for just a sec. I have replaced EVERYTHING else like I said. I'm thinking it's a broken AFM because no matter how much I adjust it, nothing changes.

[Knockenwelle]

Don't rule out vacuum leaks until you've ruled out vacuum leaks.