gomer

iTrader: (13)

I went and dyno'd my car today. I was logging each run with HP tuners and noticed that my MAF reading was acting crazy. At lower RPMs and part throttle it was barely reading anything then at WOT it would start spiking to zero and back above 6,000rpms. I have a screenshot of the log below. I took the maf off and cleaned it.. that didn't make a difference at all. Do you think the MAF is going bad?

wrencher

iTrader: (2)

Could be a bad maf or a bad connection, I'd test it at the maf w/ a scope. That takes the PCM & the out of the quesswork.

gomer

iTrader: (13)

I have a tektronix TDS 360 digital scope I can connect to it. Which wire is the MAF output that I would need to connect the scope probe on to?

jimmyblue

iTrader: (11)

The "5V" line is really a pullup load to 5V and the
MAF output is an open-collector driver that pulls
down a narrow pulse. I'd push a sewing needle
through each of the harness wires and clip the probes
to those, look for intermittent wierdness on the output
and the +12 power (esp. with wiggling the connector).
That's how I put the 'scope to mine, anyway (just for
educational purposes).

Billiumss

iTrader: (11)

It's a problem with the scanning software and HP Tuners knows about it. I have only seen this on Forced Induction cars.

If your A/F is good and you don't have any knock, I'd say your OK.

Hopefully HP Tuners will fix this bug in thier next release.

gomer

iTrader: (13)

Thanks for the info! That makes me fell much better about the whole deal. The A/F was good and there was no KR.