at a loss. replaced MAF

[L31MaxExpress]

is the MAF ignored as well? the FUEL TRIMS go to zero

The programmed values for the VE table that is programmed according to MAP & RPM and the filtered MAF values are blended together.

 

[Chevy Express]

The programmed values for the VE table that is programmed according to MAP & RPM and the filtered MAF values are blended together.

SO the MAF is in use even at WOT? Am I understanding this correctly?

 

[L31MaxExpress]

SO the MAF is in use even at WOT? Am I understanding this correctly?

Correct, from a couple of seconds after startup it is used.

 

[Chevy Express]

well i just bought a poor man pico. has to be the wiring to the MAF, I have a feel the scanner just isn't seeing it.

 

[Supercharged111]

MAF is blended with MAP below 4000 RPM, above that it is exclusively MAF in stock form. I'm actually running both my trucks MAF only with a custom tune and they're way less sensitive to altitude/weather changes. Your issue really sounds like a wiring problem.

 

[L31MaxExpress]

MAF is blended with MAP below 4000 RPM, above that it is exclusively MAF in stock form. I'm actually running both my trucks MAF only with a custom tune and they're way less sensitive to altitude/weather changes. Your issue really sounds like a wiring problem.

I guess that depends on what tune you are looking at. GM changed that around a bit depending on year, engine size, etc.

With that setting stock in my 0411, I had a slight dip in AFR right where it transitioned to MAF only at ~4,800 rpm.

 

[Supercharged111]

I guess that depends on what tune you are looking at. GM changed that around a bit depending on year, engine size, etc.

With that setting stock in my 0411, I had a slight dip in AFR right where it transitioned to MAF only at ~4,800 rpm.

Weird, in my (limited) experience it seems GM chose 4000 as the magical transition point for the blackbox and 512kb 411.

 

[L31MaxExpress]

I would start with the engine grounds first, make sure they are clean and tight.

One other item that might be worth to check. The PCM filters most of the sensors reference voltage. The crank, cam and MAF sensors are not filtered by the PCM. AC ripple voltage can effect them. There are some TSBs floating around on some vehicles where a failing rectifier diode in the alternator can create symptoms of sensor failure.

xc_hide_links_from_guests_guests_error_hide_media

 

[L31MaxExpress]

Weird, in my (limited) experience it seems GM chose 4000 as the magical transition point for the blackbox and 512kb 411.

I have been into LT1s, Black Box both early and late, as well as P01 and P59. It all runs together after a while. But for the most part at WOT under 4,000-5,000 rpm its blended.

 

[ralmo94]

Did you try unplugging the O2 sensors and see if it still does it in open loop with the maf plugged in?