Hey guys, so I have a 2001 Sierra ( see sig) Engine is as follows...

2003 6.0L LQ4
Comp 222/224 cam (LS6 Springs)
Ported/Polshed/milled .015 Heads
Shorty headers
8.1 injectors

I'm have a issue after the truck was Professionally tuned, with it running rough, stalls/sputters when hot, a/c on kills engine. My tuner is thinking its an issue with fuel vaporization in the rail, possibly because I'm running the 4.8 return style intake as opposed to the LQ4 returnless style? Anyone experienced this? or something similar? Is this a tuning issue or a hardware issue. Its driving me nuts, because otherwise the truck runs so strong.

Any insight?

Thanks.

 

My first thought is maybe a header leaks when it heats up, freaking out an oxygen sensor.

 

This would set a code, no?

 

It shouldn’t have anything to do with your intake and fuel rails, as a stock 2001 6.0L came equipped with the same style intake and fuel rails as your 4.8L.

 

The 6.0L is not a 2001, its from a '03 3/4 Ton which had a returnless fuel system. However Im using the '01 4.8 intake which uses a return style.

 

I understand, you just used the intake and fuel rails from your 4.8L. My truck being an '01 1/2 ton and coming with a 6.0L, I can assure you they used the same set-up. The only thing different with mine was it came with ETC instead of a cable operated throttle-body. The 3/4 ton and up earlier model trucks used the same set-up as well, albeit with a cable throttle-body.

 

Either were talking about 2 different things or I'm not understanding what your saying which is very possible it has been a long day....

The injector rail for a 99-02 4.8/5.3/6.0 IS different than a 03+ injector rail. If you look at the link I attach, the 8th picture down shows a 03 LQ4 injector rail with only one Fuel outlet (returnless style) the 99-02 have 2 fuel lines (return style)

https://www.performancetrucks.net/fo...-stuff-467773/

 

Your 6.0 will run perfectly fine using the return style fuel system.

It sounds to me like your tuner needs to do some more work on the idle airflow tables.

 

I wondered that...Its not an overly huge cam by any means...

 

I'm running a 2007 LQ4 in my 2000 silverado with the 2000 intake and return-style setup. Everything works fine. I would start with looking at your tune.