Hey guys, I have kind of an odd situation hoping you can point me in the right direction. I have a 2006 GMC Sierra that I recently swapped an lq9 into, 228/234 cam, CNC/milled 799s, ls2 TB, ls3 injectors and tbss intake.
I brought it too a tuner, who did his best to get it dialed in, but it wasnt quite right. Anyway, I decided to roll my sleeves up and try to get it running better on my own. Fast forward a few weeks and the truck runs "well" but not perfect.
My current issue im trying to iron out is a condition where as I enter the freeway, fully warmed up, CL etc, as I begin to come to crusing speed the truck will lean out, o2s will go flat to like 60mv (roughly), and it sit between 16.5-17.0afr, it will seem down on power a bit. This will continue maybe 3/4 minutes of driving. Then I'll feel a change in power, it will pick up in power, then it will be 12.9-13.2 afr, this again will run for 3/4 minutes.
Eventually, the truck begins to "settle" and I'll have a normal 14.6 afr, o2s go back to cycling, and all is well. Now I know it has to do something with the MAF, as SD mode it runs "perfect", gets way better mpg, and afr doesn't fluctuate on the freeway at all, and response as it should.
Again I'm new to tuning and have done my best to research but I haven't come up with much so far? Any suggestions?
I hope this works, first time I've tried to upload file.
Log and file>>>
Freeway leanrich.hplracetruck-Justin ve maf pe.hpt