What could cause a MAF fail on LS7 E38?

[bradyzq]

Hi All,


The car in question is a 2008 Z06, running the stock OS. It's already scaled 50%.

Dynamic airflow is set at 200/100RPM, so MAF only for now.

The "MAF Fail High" is set to 14500Hz.

The car touches 11600Hz, and gets VERY close to the 512g/sec limit, at which point the MAF fails at 5400RPM WOT.

I would think there'd be at least another 600HZ before there would be an issue, if not more...

Any idea why the MAF fails when it does?

[Frost]

So you are getting P0103?

[bradyzq]

Hi,

Actually no I'm not! At least not that I've noticed.

I have a MAF Fail Status bit on the scanner, and it goes positive under the above conditions.

Around the same time I also hit the max 1.36g/cyl on the timing maps and 512 g/sec.

I will dial in the MAF better (too rich right now) and that will bring down the g/cyl count too.

On a side note, I am encouraged to see that my Dynamic Airflow is in the right ballpark. Props to the Bluecat tool!

[bradyzq]

Hi All,

New data:

I do NOT have any codes that arise from this, simply the MAF fail status bit goes red and says "Yes."

I have dialed in the MAF better and now see only 1.16g/cyl or so, and don't hit 12200Hz. The MAF fail now happens as of the low 11000's, or around 400g/sec.

The car still runs fine, even on a pull, so there may be no real effect here, but I'm VERY curious about this!

[Pekka_Perkeles]

Any idea why the MAF fails when it does?

VE.

Maybe it should not, but I have seen it failing MAF.

[Frost]

If the MAF fails, you get a MAF fail code (that is what triggers SD and *IS* the failing of the MAF). Can you describe what was actually happening? The post could be construed as confusing because MAF Fail is often thought of as a specific thing, though it seems those terms maybe used differently here.

[Pekka_Perkeles]

VE.

Maybe it should not, but I have seen it failing MAF.

I probably used wrong wording. What I have seen is that you might end into REP even with MAF only tune, if the VE is not in the right ballpark.

[ingsteve]

Remove the maf and clean it with a spray maf/throttle body cleaner..
Spray on it at 1feet distance, let it dry naturally 15min and repeat.
Do it on both side 2-3 times.

We got a lot of service traction control issues at wot (no obd codes) here in Italy and we discover it was the cause...

Give it a try and let us know.

[Frost]

I probably used wrong wording. What I have seen is that you might end into REP even with MAF only tune, if the VE is not in the right ballpark.

REP and MAF fail aren't the same thing though...

[bradyzq]

I'm hoping that the cause of this was that I was touching the max of the 2 bar MAP (not MAF) sensor. I haven't had a chance to verify yet.

The MAF is clean, and I have not been entering reduced power mode. Far from it! Touching 800WHP!

News as it happens.

Thanks for the replies!