Turbo 2009 Chevrolet Silverado 5.3 V8 - Tuning

[wgr73]

Hey guys. I have a friend who turbo'd his truck. He's having an issue with part throttle enrichment. He has an external wastegate so boost control is tough since there is no factory boost controller (currently using gate pressure of 5psi).

The main issue is part throttle tuning. Is there a way to start enrichment based off of load vs rpm, or some type of load vs open loop fueling? WOT enrichment is fine. Afr drops to target as it should. I have HPTuners and am going to tune him but I need feedback before I start. I haven't heard back from HPT yet. Thanks!

MODS:
Gt4088r turbo
72lb injectors
38mm wastegate
3 bar map (from zr1)
Blow thru maf sensor setup

[tonyvette]

I banged my head against the wall with this issue also. Finally realized that the MAF sensor was the culprit. Just really difficult to tune blowing thru the MAF. I disabled MAF and now run solely on Bluecat-tuned SD. Runs great!

[wgr73]

I banged my head against the wall with this issue also. Finally realized that the MAF sensor was the culprit. Just really difficult to tune blowing thru the MAF. I disabled MAF and now run solely on Bluecat-tuned SD. Runs great!

Interesting, that sounds like it's exactly the same issue! What method did you use to disable the maf?

[tonyvette]

I set dynamic airflow disable to 6500rpm, re-enable to 6400rpm and MAF frequency fail to 0. Also set P0101, P0102, P0103 to 0.
MAF still has influence over AFRs for some reason, even with these changes, so I also unplugged the MAF after relocating IAT sensor to the intake manifold.

[wgr73]

I set dynamic airflow disable to 6500rpm, re-enable to 6400rpm and MAF frequency fail to 0. Also set P0101, P0102, P0103 to 0.
MAF still has influence over AFRs for some reason, even with these changes, so I also unplugged the MAF after relocating IAT sensor to the intake manifold.

Gotcha. Nice man, thanks!

[GXPLS4]

I didnt want to start yet another thread on this issue with 2 BAR OS, I decided to puill the MAF wires only out of my MAF sesnor leaving only the IAT and assoiated wiring in place started it up and engine choked out hard....all of this time ive been thinking my MAF has been failed but maybe not, if any one could advise id appreciate the help as always



2BARcobaltmap.hpt

[tonyvette]

@GXPLS4
When I disabled my MAF without unplugging it, I could see in my logs that MAF was still influencing AFRs, lean during part throttle acceleration and rich at full throttle. When I unplugged the MAF my truck wouldn't start. It would crank and fire up then immediately drop dead. So I plugged in the MAF, fired up the truck, then unplugged the MAF again. Truck stayed running doing it this way, so I went on a datalogging run and saw that my trims were much more consistent with the MAF unplugged. But obviously I had to get the truck to start without having to plug and unplug the MAF, so I datalogged trying to start the truck with MAF unplugged. Log showed AFRs around 7.90-8.00! I then multiplied my 400rpm column/row in the VE table by .90 to remove fuel during cranking. Truck fired right up and settled into a 625rpm idle. Problem solved.

Sidenote: Multiplying by .90 was my 3rd attempt. Tried .75 first, then .80. Neither of those worked although .80 would stumble badly and finally "catch" about every third try. So if you're having the same problem and .90 doesn't work, go up or down in .05 increments and try again. I'm far from an expert at this stuff but it worked for me!

Hope this helps!