Help! Maxed MAF = No Fuel!

[BlackGS]

I went to the track tonight, and had a big problem. I maxed out my MAF values, hitting 11500-11700 during the first run. What really gets me is that when I hit the MAF ceiling, fuel was cut, and I ran way lean, causing massive KR. I don't think any engine damage was done, as it seemed to pull fine on the way home with no rough spots.

Why was fuel cut? Shouldn't the fueling stay the same as the highest cell even though it goes beyond that? Thanks for any info. I sure don't want to run again until I get this figured out.

[BlackGS]

My MAF fail frequency was set to 11500. As I think more about this, I'm guessing the MAF went into fail mode, and maybe VE took over?

[minimoe]

That sounds like a good idea. I think that is where the stock MAF table tops at 11500 and that is why the default cutoff is there. I'd assume that if you just raise that fail point, then the PCM will just keep the last airflow vs Hz even as the airflow increases. In that case, you'd think you are ok as you just go over by 200 Hz.

I'd still say ouch for the KR and lean conditions. Doesn't take much to wack a bearing (watch oil pressure in your cruising around) or ding a piston (pull a plug and check that).

Great to see that with your wideband. I just installed mine and need to get it logged with HPT via EGR.

-Scott

[Perforator]

Time for a AFC for you. What time did you run?

[BlackGS]

I guess I'll try raising the fail point and see what happens, but I am definitely going to look around for an AFC, or maybe an LT1 MAF.

That run was a 13.1 at 105.7. I went home after that as I didn't want to risk any damage. I removed the MSP CAI before going to the track. I think that is what increased the airflow.

[Perforator]

You don't have a 85mm maf?

[BlackGS]

You don't have a 85mm maf?

I have the LQ4 MAF with the N* TB. I don't think I should be maxing that out with my mods, but I did.

[Perforator]

Yea I wouldn't think so either, at least not with this warm of weather. I did last winter with the 2.8 but it was in the 20's.

[BlackGS]

It was around 50* last night when I left the track. I had the 2.8 pulley on, and as you can see in the scan, I was well above 14psi. I just ran two weeks ago with the exact same setup and didn't have this problem. I think it was around 60* that night.