Where is this Timing Coming From?

2005 C6, I've locked the High/Low octane spark tables to 14 degrees (same superchared C6 I've been having problems, I think before I had said it was a 2006, with all week, but things are good now, aside from this), yet on WOT dyno pulls, the car is receiving 20+ degrees of timing. Needless to say there's a lot of knock because of that. I've gone through all the Multiplication and Addition Spark tables, and zero'd them out for the time being to see if that's where my extra timing was coming from, but it's still there.


Thanks,

Mike

PS. you guys are the best, I've figured almost all the problems I've had with this car just by reading you posts.

Here's the latest file from the car. AF is a straight 12.0 with a slight dip to 11.9 at 5600rpm.

Mike

Try zeroing the Spark Correction AFR > Gas table. What is the wot g/cyl?
Why is your commanded afr set from 10.24 to 8.29? Thats with a stoich afr of 14.7, you have 14.0 which would change the commanded afr to 9.75 to 7.89! Now your maf table is way too low, so maybe the spark table not on the right g/cyl because of this. If you whant a 12.0 afr, then set the pe to 1.225. Then set the stoich to 14.7, then rescale the maf or ve table to get an actual 12.0 afr.
Also the pe delay rpm should be 0 rpm as pe is delayed below the rpm you have it at.

Russ Kemp

With PE set to 1.30, car's actual AFR was 16.4 at WOT. The VE table is pretty much set (I must have left the Command AFR at 14 from a previous file while I was trying to see if I could get the damn thing to work right), the LTFT and STFT histograms are pretty much zero'd out (see attatched log). When I set the MAF fail back to 15000, and they went way rich, -13/-25 respectivaly.

As I look back at some of my other files, all the other S/C cars I've done did have the PE in the 1.28-1.35 range, I have no idea why the car is acting this way. The stange things you see in the airflow/fuel tables are the results of hours upon hours of logging, scanning. The LTFT and STFT are very close to zero now, and the car runs damn good for only seeing 3.5lbs of boost (need to get a smaller pully). The Spark Advance>Spark Correction AFR>Gas table is set to zero at 4000rpm (starting dyno pulls at 3800rpm due to no trans controls on the Scanner). Plus that table only adds spark, and is maxed out at 2 degrees, I'm seeing as much as 11 degrees added to the High/Low Octane tables. I've even gone back to my stock file, and reloaded every table onto that file, and then rewriting the entire VCM, and the consecutive pulls are near identicle (hp with in 2, and tq within 4, AFR identicle). The PE throttle position was set high so that it wouldnt kick in early while trying to get the VE table right.

I'm actually surprised the car runs, but not only does it run, but it's scary fast. It's hazing 315/30/19 drag radials until you let off the go pedal. This car makes no sense. :banghead:

Ok I spent some time going through the HPT file and there are some major issues. The timing problem is a result of you MAF table being very far off.

Your MAF table peaks at 260.7 g/s. This is about 50% lower than the stock calibration. At 6000 RPMs the highest g/cyl you could possibly see is 0.65. With your timing tables the way they are you would be seeing about 25 degrees of timing before any adders.

Your VE and MAF tables are way off. Assuming there was no error in the wideband readings this would tell me your injector flow rates and/or injector offsets are out of whack and the VE/MAF tables have had to drop that much to compensate. If you want a quick bandaid to your timing problem then you need to make changes in the lower g/cyl areas of the timing table. The downside here is that you have lost a lot of resolution having to drop the tables so far (VE and MAF).

Tim