KR at 1800rpm, 25% TPS

[87gtNOS]

Ok, someone please excuse my lack of knowledge with this stuff....

Between 25 to 35 % TPS, I get up 4 to 6 deg KR.
RPM is from about 1700 to 1900.

I can make it do this anytime.

I saw this using my VCM scanner. I tried to save the file, but the scanner froze!

For the fun of it, here is a screen shot of the scanner, as I idled in my driveway.

Thanks

[Twitch]

Post your tune. And try to get another scan for people to look at.

[12secSS]

Solely based on calibration, the only times I see what you experience is in two scenarios: Excessive timing or Excessively lean. Seeing you ar ejust at 17 degrees, I would say you ar eevery lean, do you have a wideband hooked up, and if so what is it reading during this scenario.

Aside from the calibration aspect, you could have something rattling around in the engine bay or drivetrain area causing false knock. Inspect for the usual: exhaust rubbing on chassis, loose heat shields, loose hardware, etc ...

[2xLS1]

Solely based on calibration, the only times I see what you experience is in two scenarios: Excessive timing or Excessively lean. Seeing you ar ejust at 17 degrees, I would say you ar eevery lean, do you have a wideband hooked up, and if so what is it reading during this scenario.

Aside from the calibration aspect, you could have something rattling around in the engine bay or drivetrain area causing false knock. Inspect for the usual: exhaust rubbing on chassis, loose heat shields, loose hardware, etc ...

Um, the car is idling and not even moving there.

And to the OP, with as few details you give, who knows. Scan shows 99 Vette, but that's all. A4 or M6? What gear are you in when it is knocking? What mods are on the car?

[87gtNOS]

Yes guys, sorry I know, very vague...
It's a 99 vette, with M6. Stock MAF, ported stock TB, Longtubes, no cats, no rear O2's, Blackwing CAI.

Did some more logging today, but I cannot save the log tunes....stupid ".net framework" BS that HPtuners says is not a problem!!

Anyways...Here is a pic of my histogram. There are no values below 0.60 grams (I scrolled down to look). I think this is indicating that my MAF needs to be calibrated?

I cut and pasted the stock timing table into the table I was using in the 1400 to 2000 rpm range and it still pinged.

I was also able to save some logs and histograms....sometimes I got the error and sometimes it worked....

[87gtNOS]

here are some logs and histograms...

[2xLS1]

Quit lugging the engine. You are trying to accelerate in a very high gear/low rpm while in closed loop fueling. Your transmission has 6 gears for a reason. Downshift.

[87gtNOS]

Quit lugging the engine. You are trying to accelerate in a very high gear/low rpm while in closed loop fueling. Your transmission has 6 gears for a reason. Downshift.

Yes, thanks.

Any thoughts on the grams/per cyl only going to a max of 0.60?? Shouldn't it hit like 1.0 at WOT? (this indicating the MAF is way off?)
I multiplied my MAF HZ table by 1.1 and the gr/cyl now goes to 0.68.....

If the MAF is out, then the advance I am getting when it KR's, is simply due to the car using the wrong part of the table?

Thanks for answering my dumb questions!

[2xLS1]

Stock heads/cam ls1s usually see from .60 -.68~.72 g/cyl at wot high rpms. You would only see 1.0 with forced induction. Fuel trims can be an indicator of maf calibration in the lower rpms and PE commanded vs actual A/F in the higher rpms from 4000 rpm and up unless you lower the high rpm disable paramater.

If you want to accelerate from those rpms in a high gear you could try lowering the PE enable TPS to at least get it in PE mode and out of closed loop.