Anyone want to look over a 5.3 tune for my son's drag car?

[1991_z28_5.3]

Gstorey- good point on the bend just after the MAF. Since it’s a 5 wire truck MAF with IAT, I’ll hold off on the MAF mount piece. That would require some wiring changed and new sensors. I’m hoping to quit throwing parts at this thing. Good info that I’ll keep in mind. I’ll absolutely move the MAF closer to the filter to see if there’s any effect.

[2xLS1]

If you just fail the MAF and run it in SD mode and still have the trim imbalance then it is not the MAF location. Also the next time you change plugs just put in the cheaper NGK TR55 copper cores.

[1991_z28_5.3]

If you just fail the MAF and run it in SD mode and still have the trim imbalance then it is not the MAF location. Also the next time you change plugs just put in the cheaper NGK TR55 copper cores.

I tried to fail the MAF earlier in this process, but was not successful (or didn't think that I was). As I understand it, I set the fail frequency to 0 Hz, and set the P0068 to MIL on first error. Am I missing any steps there? I just picked up the NGKs that were in stock last night at my local parts store, but I've seen a lot of good things about the TR55 plugs.

[2xLS1]

P0068 is a MAP sensor code. You need to set the MAF codes to MIL on 1st. P0101, 0102, and 0103. Really just 0103 since it is the one that will set with MAF fail at 0hz, but most change all 3.

[1991_z28_5.3]

P0068 is a MAP sensor code. You need to set the MAF codes to MIL on 1st. P0101, 0102, and 0103. Really just 0103 since it is the one that will set with MAF fail at 0hz, but most change all 3.

Copy that. I’ll make the adjustment and see how it runs. I was thinking about the rich condition this morning, and thought of something. I am currently using a VE table from an LS1 Firebird tune (from the tune repository). I made that decision based on a couple of threads here where the poster used an LS1 intake on a 5.3. The truck intake flows so differently from the car intake, and the theory is that the car VE table should be closer. That said, the LS1 is a larger displacement engine. Is there a way to scale the car VE table down to better match the 5.3 displacement across the board, or is it a trial and error operation? I’m wondering if that might account for the rich mixture that I’m seeing - well, smelling. Granted, I’m not sure that the VE table is used during idle, so that could be way off too.

[2xLS1]

Engine>Airflow>Dynamic>High RPM Disable will be a RPM value. Below that RPM the PCM uses a blend of both VE and MAF for airflow data. Above that RPM the PCM will use MAF only.

NicD has some good information on using HPT and how VE is displayed here.

https://ls1tech.com/forums/pcm-diagn...ent-value.html

[1991_z28_5.3]

I'm pretty stoked about this! I started thinking about what the injector shop said about LS1 injectors, and remembered that for an LS1 Camaro, 99,01 and 02 had injectors that flowed 28 Lbs (may have been 28.8lbs, but the same flow across all 3 years). 2000 had injectors that flowed 26.2. I went back and saw that the LS1 tune file was labeled as being for a 2000 Firebird. I grabbed a 2001 Camaro LS1 tune (actually 2 of them to compare) from the tune repository, compared the injector data to what was in there, and decided to give it a shot with 2001 injector data. It idles like a champ now! My newly installed AEM UEGO wideband shows decent AFRs while idling, it revs and idles back down smoothly now too. I'm fighting with the wideband to get it to log in VCM Scanner, but I'm not losing sleep over it right now. The main thing is that this dude is running pretty well, finally. I'm posting the log file that I just grabbed, along with the tune file and the config for the log. If one of you smart folks wouldn't mind glancing over it and suggesting where to go from here, I'd really appreciate it. Thanks a ton!

[GHuggins]

Relocate the MAF closer to the air filter (the bend after the MAF is just as important as the one before it) and then tune in your fuel trims via the MAF and VE tables. You fixed the bank to bank with the plugs and some of the fueling with the injector data. Now finish it up

[1991_z28_5.3]

Relocate the MAF closer to the air filter (the bend after the MAF is just as important as the one before it) and then tune in your fuel trims via the MAF and VE tables. You fixed the bank to bank with the plugs and some of the fueling with the injector data. Now finish it up

Thanks for all of the input. I’ll swap the MAF around and then stumble my way through the rest of it. We just got back from a very short test drive, and it’s doing all the car things (go, turn, stop) very well. It was a last minute victory because my son entered his car 2 months ago in the annual car at his high school, to benefit the auto tech program. He will be the only freshman showing his own car. It’s tomorrow morning, and I had already decided that it was either driving there or being trailered there. I’m just happy that it’s drivable! I’m taking the victory today and will worry about dialing it in later this weekend.