I have a 2007 C6 that I've added an A&A T-trim kit to. Because we don't have too many experienced (LS) tuners on island, I went with a tuner that was recommended on the mainland and sent datalogs/tunes back and forth. I've run into a problem with the MAF maxing out at 5400 rpm. I put the car on the dyno today and she pulled a mere 446/416 on 92 Octane and 7lbs. The lines are nearly straight until it hits the 5400 area, then she flatlines and breaks up.

Is it normal for the MAF to max out so early on such a moderate amount of boost? Do people usually change the MAF to a card style like the LS3/LS7 or do the just go speed density? I'd really like to keep the car tuned with the MAF.

Thanks,
Ryan

 

Need a log to tell for sure but you might be out of MAF and without a 2 bar to go SD you will have to go old school and add fuel with the PE. Not the greatest way to fuel the car though. Where is the MAF at 5400 RPMS?

Your tuner should be able to correct this with the logs eitherway.

 

The MAF reads 483 g/sec at 5600 and is reading 485 by 6200 and is flat the rest of the way.

My tuner says he can't do anything more without being here or having the car in his shop. Neither are going to be happening soon.
Can a new map be loaded for the MAF? Changing the calibration of the MAF. Has any luck been had using the LS3/7 MAF or the Lingenfelter 100?

Thanks

Ryan

 

The stock LS2 2007 Corvette MAF readings should max out at 511.9922 grams/second (basically 512) at 12200 Hz and above. 12,200 Hz is the highest frequency that software is designed to understand so the MAF reading will be pegged at the last table value for all MAF readings above 12,200 Hz. That is assuming nobody has changed the MAF table values.

If you don't have a way to read the calibration out of your ECM but you can log data, log MAF airflow and MAF frequency and compare the two. If you aren't getting to 12,200 Hz then you aren't pegging the MAF sensor. If you are getting to 12,200 Hz but the reading is only 485 then the table has likely been modified. Make sure you are looking at the actual MAF airflow variable and not the calculated one as those two readings will be different.

In addition that year software has a maximum MAF reading of 511.9922 (512) grams/second so even if you have a MAF sensor that outputs a lower frequency for the same MAF reading (or reads a high MAF value for the same frequency value), the 2007 LS2 (and LS7) Corvette ECM won't be able to understand the readings.

Changing to a blade type MAF sensor (LS7/LS3) or the Lingenfelter 4" MAF isn't going to change the maximum airflow reading the ECM can understand.

Depending on your engine efficiency, 512 grams/second should equate to about 550 to 650 hp at 6000 rpm but you can support much more than that in terms of power and still run a MAF based system.

In order to provide the correct fueling once the MAF sensor reading is pegged you can just target richer target AFR values in the power enrichment (PE) table. For example, if you are at 11.5 AFR and you are commanding 11.0 AFR at 6000 rpm and you really want 11.0 you may have to command 10.5 at 6000 rpm and above (just an example). You only need to do this in the RPM areas where you have the MAF sensor pegged.

Hope this helps.

 

Thanks. That does help. Thanks for explaining why changing the MAF won't help. Most have just said it will not work without saying why.

When I get back, I will look at the tune and logs and see what the freq is at the upper end of the table and compare that to the original table.

Thanks again,

Ryan

 

Are you out of fuel pump or injector?? I run a twin, in-tank pump setup and 60# injectors for my D1SC. IIRC, the single Racetronix pump wasn't getting it done...

 

I don't think I'm out of injector or pump. I'm running 60# injectors and the Racetronix BAP. Injectors hit 87% duty cycle at 6500 RPM and the car is rich by that point.