GM MAF problem?

[allezgrand]

I've been fighting quite a few different issues and seem to have resolved most of them, but the car still runs poorly:

1) In ECMLink, I've tuned it at idle quite a few times, but it continues to change. I warm it up fully every time. Each time I will get the Airflow per Rev around .26-.27 (the block is bored to .020 over) and the CombinedFT cycling between -5 and +5, but the next time, the CombinedFT will be way off: either positive or negative.
2) I was having terrible knock and with continuous adjustment finally got rid of almost all of it, but my timing table is less than 8 deg BTDC at loads over 1.0 and around 0 deg BTDC at loads over 1.4. And even with this, I still get .4 deg of knock at WOT sometimes.
3) When I run MAFComp Adj after a cruise, it suggests new, different values every time.
4) My wideband AFR is very inconsistent with my AFREst, even at idle. I can adjust the sliders and get it damn close, but it is likely to be off then next time I drive it.

These seem to me to be pointing to signs of a bad MAF (I am using a 3" GM MAF right before the throttle body and have leak tested the system several times), but I wanted to get some other opinions before replacing it or spending the time and money on speed density equipment. Has anybody else seen these MAF's go bad? Thoughts??

 

[allezgrand]

In case others search and find this:

I had two main problems. First, I had not set the switching value of the AEM wideband to the appropriate level for my car, and second, most likely due to the lack of utilizing any FPR prior to the new AFPR, the fuel pump isn't flowing properly so my AFR was too lean under load. I haven't fixed the second, but I imagine that will clear things up.

 

[boost97gst]

THnaks for update. Im having similiar issues. I have a 2g maf though. Combinedft justtakes off up to 16% positive even after warmed up sometimes and ill redo maf and deadtimes.... Frustrating

 

[allezgrand]

I assume you've already done a boost leak test, and measured your fuel pressure?

Have you tried posting an idle log to this forum?

 

[95talongirl]

The .4 deg knock is nothing to be concerned with from what I've found out. When it's over 1, that's when it's a problem.

As you found out, AEM Wideband usually requires some finessing to get it to read correctly with Link. This is a good video for that:
Calibrating AEM UEGO Wideband with DSMLink/ECMLink - YouTube

Good luck!