Pinging, Bad MPG and Bucking

[jbassking]

Hey Guys! I'm hoping someone can help me out.

The log doesn't show a lot of ping but I can hear it under light acceleration, mainly under 2000 rpm. I always run 93 octane.

I know my MPG won't be as good with the new cam but after this tune it's really bad. I average 15.4 overall but I primarily do highway.

The last issue is the bucking. This is usually when I'm coasting between ~35-40 MPH.

One last one I just remembered, when slowing to a stop, as in coming up to a red light, going into 1st makes the car lurches forward.

By the way, I think WOT is pretty good although I never put it on a dyno.

Sorry the log is so long. I wanted to capture normal driving.

I'd greatly appreciate any help. This is driving me crazy!


https://www.dropbox.com/s/vo4q15nxrz...0home.hpl?dl=0

pinging bad mpg bucking.hpt

[momotunes]

I'm on my cell phone so can't look over anything but bucking in my experience is large transitions In fueling from one cell to the next (MAF or VE). Side effects of that is knock. I've seen running airflow cause it as well as large swings in timing between cells. Assuming trans settings are okay.

Also, did you check your pushrod height when you put your cam in and did you use new lifters/inspect the old ones if reused? I've seen LS motors make what sound like pinging/chirping at lower rpms from torn up lifters. This wouldn't really cause bucking though. I'm betting that issue is from the above.

[jbassking]

I did change the lifters.

The ping is only during initial acceleration.

How can I tell if the issue is with the MAF or VE?

[momotunes]

Send me the tune file, a log file, and full cam specs. I'll review it and provide my recommendations for injection timing and see if I can spot the area. Also send the stock tune please. I don't have a Dropbox so if you have a shorter log that would be awesome.

[jbassking]

Here's a smaller log. This a L99 in a 2012 Camara SS

normal driving.hpl

The cam is a TSP Stage 1:
Duration: .050 223 233
Lobe Lift .370 .370
Valve Lift @ 1.7 .629 .629
Lobe Separation 114
Intake Center line 107

[momotunes]

Disable VCT in the tune, zero out the VCP spark table, set injection boundary to "500" from 0 to 2048, and work on your VVE table. The bucking is most likely coming from the areas I have circled. Another helpful table to set up/scan (if you haven't already) is to make a histogram matching your VVE table but log spark retard. It can give you a good idea of problem areas too.

VVE Table Picture.PNGInjector.PNGPic VVE.PNGScanner Knock Example.PNGVCP Spark Table.PNGVCT.PNGVVE Table Picture 2.PNGVVE Table Picture.PNG

[jbassking]

Thank you @momotunes. I'll see how much of this I can figure out.