I have a problem with my BMW 318 '98. The engine runs very lean and has no performance at all.
When I do the snap throttle test the air-mass meter doesn't go above 3,5 Volt. Can I asume the air-mass meter is defective? Here's the waveform with lambda signal in red:
Thanks for your reply, as far as I can tell there are no vacuum leaks. I've checked it all. Tonight I will try to clean the air mass meter and see if there is any difference. You wil find the results in this topic tomorrow.
On that engine/system I would expect to see an initial "spike" of over 4.5 volts. This is assuming you are snapping it WOT like you don't own it. A quick look at fuel trims may also aid you in condemning the MAF.
I did the trottle test WOT until the rpm limiter. I have cleaned the Air-Mass meter and the engine runs much better, but I'm still not happy with the second throttle test. As you can see the voltage is a little bit higher, although the lambda signal still shows lean. Shouldn't the lambda give rich during WOT?