I have a 2009 Pontiac G8 GT, the original L76 decided it didn't like oil pressure. It is now a AFM Deleted 402ci stroker (mods below)
Texas Speed 402 Rotating assembly (10.6:1)
Stock Heads w/ .660 springs
Texas Speed Stage 1 LS3 Cam (225/236 114LSA)
Kooks Long Tube Headers
SOLO 3" street race exhaust
CAI
Stock Fuel System
Once the car was assembled, I took it to my tuner and we put it on the rollers. We didn't push it extremely hard being that it was a fresh motor. Once I got the car back home (Trailered) It wouldn't stay running, it would die at coastdown (2-1 shift). My tuner then decided to just leave me hanging, so I bought HPTuners myself and decided I'm going to learn and try to tackle this myself.
Currently the car does "OK" The biggest issue I keep having it MAF (P0101) and Idle speed (P0506)...Ive recalibrated, smoothed, even replaced and redid all those steps on the MAF. It runs ok, it idles ok, but rolling into the throttle around 3500 It falls on its face, cuts timing back, it picks itself back up but this is the most aggravating problem.
I'm new to the tuning area, I don't understand all of the terminology quite yet. I will add my most recent LOG and TUNE below, if its something simple to fix then that's great, if not I will take to a shop local that has way more experience than I do.
I'm new to the tuning world as well, and can sympathize, even had the MAF sensor error trying to get my stroker build streetable after i had mine 'tuned'.
I'm from the Gen III side, but a few things I looked at for mine.
- The MAF sensor, my understanding is there is an error % the computer is using to compare the VE table to the MAF. Each will be used to calculate a final Airmass (grams/sec). If there is a significant difference between the two calculations, the computer will think you have a vacuum leak or a faulty MAF and give you an error. (Even if the MAF is 'calibrated') The sensitivity or allowable error between the two can be adjusted to just make the error 'go away'; likely won't fix any low RPM Or low load problems..... or tune try and tune your VE table for your set up.
- I went back to the drawing board and did my own VE street table.
(Ignore the following if you already did a 'street tune' for your VE)
Essentially turning off the MAF and running speed density.
( insert a few hours of Youtube and forums to make sure all of the parameters are set to accurately do this i.e. Cat over temp, DFCO, ect)
- Keep it out of power enrichment mode. (likely less than 60% throttle and under 4k rpm to start)
- Keeping it in closed loop and in the range of the narrow band O2's is very important.
- You can log "command AFR" and make sure you are not going to open loop (like you did on some of the end of your log)
(when you look at your log, you did go into command AFR 13.36, at 2500 rpm, and 60% throttle... you went lean as you saw in the fuel trims, timing was pulled to about 11 deg, and probably fell on its face (?)... (I didn't have the knock sensors on the log file opened to see if they activated)
The 'idle speed error'.... don't know about that one. I would guess adjusting the VE may not change the idle parameters.
But again... insert a few hours of self-education how to adjust idle on a built Ls 4th gen would likely be in order.
(or just bring it back to the tuner..... figuring it out yourself vs $$... the game I tried to play anyway).
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Originally Posted by K Rob
