WTF? L94, serious KR, negative fuel trims

[Mike_Levy]

Is this common for the 6.2L VVT AFM motor? Did two logs to plug into Redux, and the fuel trims didn't go positive once. And to make matters worse, there was 8° of KR in one of the logs and 16°(!!!) on the other. What gives? You guys aren't using the old L92 tunes on the L94, are you? The L94 replaced the L92 in 2010 and added the VVT and AFM. No idea what else was changed. GM isn't real open to giving up info.

Anyway, I tried to attach the logs, but the forum won't let me.

[Mike_Levy]

Its definitely the tune. I just ran it with the stock tune. Other then a jumpy idle due to the ported TB, it runs better. KR is way down, fuel trims bounce between positive and negative like I'm used to. The L94 tunes need work, if not a complete rewrite.

[Mike_Levy]

Any thoughts on this guys? Was the tune just carried over from the L92?

[Mike_Levy]

Heres a log of the tune on the truck, start-up and idle, with the Redux +5% fuel. Running rich and won't idle right.

[Mike_Levy]

Put on the 87 tune, because all I could get was 87, which I waited 2 hours and 45 minutes for. She popped a pair of codes. P0171 and P0174, lean on both banks. Heres the log I was doing right before it happened. God, the GM Dashboard is worthless. Theres absolutely nothing useful in that log.

[mikel]

the tune aint causing lean codes unless your slopes are way out of whack, IMO you have a leak somewhere...

[Mike_Levy]

Where could it possibly have a leak? The exhaust is stock. There no place back there for air to get to the O2s.

[Ill_Born_SS]

On a GM the leak can be anywhere behind the front of the MAF.... that being said it is probabaly the ported TB as they are without air idle speed motors and are extreemly sensitive to the porting/dirt/oil residue, as is the MAF. You got an aftermarket air filter also?

[Mike_Levy]

Yes, aftermarket intake from K&N. I'm putting everything back to stock right now. The codes popped again, so I'm taking it to the dealer tomorrow.

[mikel]

On a GM the leak can be anywhere behind the front of the MAF.... that being said it is probabaly the ported TB as they are without air idle speed motors and are extreemly sensitive to the porting/dirt/oil residue, as is the MAF. You got an aftermarket air filter also?

+1

[Mike_Levy]

I'm wondering if the problem was the K&N? Back to the stock intake, no rev bouncing, no nothing (light is still on. Dealer said not to clear it). Maybe I'll just pick-up an intake pipe from Airaid and keep the stock airbox and MAF location. Still have the TB I ported on there. I sold the stock one.

For a world renowned company, K&N sure seems to be more hype then anything else.

[mikel]

I think you are on to something...

[Ill_Born_SS]

^^^^

and do yourself a favor and get and install a set of NGK iridiums (TR7IX) 2 steps colder than stock, gapped at .035". The swampwater they call gasoline is not what you think it is.

[Mike_Levy]

Blah. I gotta change the plugs on a truck with just 1,000 miles on it? Stupid gas. At least access is good on the drivers side. Not so good on the passengers side.

[Mike_Levy]

Dealer couldn't find any problems with the truck, so it looks like the codes and poor running were likely due to the K&N. I'm dense, so I'll probably try it again at some point, but for now I'm sticking with the gutted stock box and I ordered an Airaid Modular intake tube.

I'll try the updated tune as soon as I can get my hands on some 93 octane or E85. Its still not available anyplace in NYC right now. I can't even get octane booster. Its sold out everywhere, even the garbage useless brands.