Then I would prolly put my factory flex fuel pump back in first! Because with the factory MAF and the factory tune it should've ran fine.... Hell I drove mine around for a few weeks with the ls3/7 MAF before driving it 6 hours away to get tuned. The Tahoe ran fine, but on WOT it would break up and run like ****. I never messed with the fuel system though. I'm still running the factory FF pump. I've heard of the fuel pressure control module causing problems for people trying to just swap in a aftermarket pump? Not sure if the exact symptoms, but that could be your problem. Or bad injectors? Where did you get them from?

 

Ok that sounds like a good idea, I can start by putting the stock fuel pump back in, and if its still the same, i can move on to putting the stock injectors back on. What im not too sure about is if the tuner adjusted the current tune for 60# injectors, and if i put the stock ones back on it might run like crap too. I dont know, but it might be worth a try.

The injectors and fuel pump are both from ON3 performance.

 

Try the fuel pump first, or the injectors! The Injectors would be easiest.... It should run fine with the stock injectors in it... Or if that's the problem, a whole lot better! Something is way outa wack! And it can only be a few things... It'll be worth it when you get it figured out!

It'll run better with the stock injectors or fuel pump, if that's the problem.... Seems really strange that you're getting a rich code! It's gotta be something with the fueling system/MAF.....

 

If you can, get the stock tune flashed back in it, and start swapping the factory stuff back in; injectors, FF pump, MAF. I would bet your problem would be solved. Let me know how it goes! Maybe some other people will give you some advice. But trust me, if it was running good before, it's only going to be one of those few things you changed, that's making it run like **** now! Keep us updated.

 

Did you buy a 2 bar map sensor for running boost?

I can only guess that this tuner didn't even trying tuning the VVE and went MAF only. Perhaps he doesn't know that the VVE is used even in MAF only mode for transients and airmass calculations.

A wideband is a 100% must here too, it would show you if it's going lean and causing these problems. Post the tune if you can.

 

When i went to get the dyno tune, i had taken my 2 bar map sensor, and he said he doesnt tune on 2 bar maps because these trucks run like crap on them, and had me use the stock map and upgrade to the ls3 maf.

Also i do have a wideband installed and its never at an equilibrium state, some times itll go all over the place, after I did get an ok tune from the guy the gauge did stay at a good range of 14-15

The dyno place is pretty well known in northern california, and has a camaro pushing over 1k hp, guys are pretty friendly. I hope he wouldnt forget to overlook something small.

 

Sounds like a shop that doesn't want to deal with really tuning it if they say they don't use a 2 bar map sensor. Basically meaning all they do it turn off VVE and run MAF only all the time. Anyone can just stick in MAF only mode and tune WOT.

14-15 afr at steady state speed is fine, that is what the stoich is at (14.7 for regular fuel). If you lean into the throttle and it stays at 14-15 afr then something is wrong. It should go straight into power enrichment when boost comes on and drops to at least 11.5 AFR on the wideband.

I'm not calling them hacks but it kind of is a hacked way of tuning. The MAF sensors are great for tuning boosted builds on the GEN 4 computers but tuning the VVE and MAF is the best way to do it.

 

Sounds like a tuning problem to me as well. I have checked everything possible on this truck. I will try and swap the injectors out today and see if anything changes.

Spoke with him today, and said its pegging out the LS3 MAF.

Where can i purchase a higher rated MAF, a pmas was recommended, but i only see they are for mustang applications.

 

I'm not sure about tuning, but I know these trucks run off the MAF and map. Hell I can unplug my MAF after the trucks started and drive around fine. With that said, I never upgraded to a 2bar map sensor. Still running the stock one.

 

How can it be pegging out the MAF, if it wasn't seeing any boost? It's not going to be the MAF that's restricting anyways, it's going to be the tubing size that it's in. With that said, I'm pretty sure the later years gmt900 were easier/better at tuning with boost. You may need to find another tuner! But I know the truck shouldn't run like that regardless, especially on the stock tune with the stock MAF, ffpump, and injectors in it. If you do all that stuff I said, it should run fine and make boost, Regardless of tuning.