Knock on supercharged grandsport

[JohnaPitt]

Hey guys,

Teaching myself to tune from ed's online tutorial. Having an issue with knock. Car is a 2013 grand-sport corvette w/ ecs kit and methanol on 93. Thinking it might be false knock but not sure. Never hear the car ping, but see pretty consistent knock with what i feel are pretty conservative timing and fuel settings. Fuel isn't perfect by any stretch but i've played around with it making it richer than what you see in these logs and it didnt make any difference. I have checked the exhaust and while some areas are tight i don't see any signs of anything hitting. I'll include an older log where i had a can of torco in a 1/2 tank. Also changed knock sensors. It was a slightly different tune then but still saw knock.

Any advice would be appreciated.

[01SLPSSM6]

After looking over log 5, at 16:40:11.5, I noticed it is going lean (15.9) at steady throttle and picking up knock 0.8 at 800 rpm and 1 mph. At 16:47:23, knock retard starts increasing around 3,900 rpms. I noticed you are running a 2 bar speed density os and the High Rpm Disable and Re-Enable speeds are set to 4,000 and 3,900 Rpm. You need to change the dynamic airflow High Rpm Disable and Re-Enable tables to 8,000 Disable and 7,900 Re-enable, so it references speed density all the time.

[JohnaPitt]

So even though the maf is failed i still need to adjust the disable and re-enable?

[JohnaPitt]

Got some help from another member on corvette forums. Made some major improvements.

[lukearmstrong1990]

wheres latest file?

[JohnaPitt]

Latest tune file?

[lukearmstrong1990]

how are you doing this? dynamic enable RPM is asking to use MAF for air mas calculation but it's disabled. the VVE table doesn't show any data above 105kpa... I'm unsure how this is working.

turn injector desoot switch disable.. will help with lean spot at throttle application

[JohnaPitt]

Thanks for the tip with the injector desoot. My vve table is set to 2bar, not sure why it wouldn't show up that way for you.

[lukearmstrong1990]

I see. It only showed map scaled to 1bar when I opened the file.

[JohnaPitt]

Phil from Tampa tuning made some adjustment to the tune for me to try out. He made the adjustments to the dynamic enable/disable and adjusted maf table as well. I was a little confused by this because the maf is failed. Am i correct that when maf is failed adjusting the enable/disable and maf table will not make any changes to fueling?

[JohnaPitt]

I've made some more timing adjustments to try and get rid of the knock on some of the second gear pulls. I was still seeing a little around 3300 rpms. Will log more tomorrow. Is 10* normal in the wot areas for a stock ls3 w/ ecs kit and meth? Only tunes of ls3 cars w/ blowers i could pull from repository all had cams as well. So I was just curious if that is a common timing number.

[lukearmstrong1990]

You had the dynamic disable / re-enable to 400rpm... this asks for the MAF.... setting the disable/ re-enable rpm or max values means you’re asking for the VVE table to be used for fueling. Having it set low can cause the PCM to go looking for the MAF occasionally causing a little splutter.


I would also suggest with your disable/re-enable RPM set to mAx you disable the 2 fast torque exit switches and max the torque values out

[JohnaPitt]

Ok, I understand the setting being at 400 is asking for maf. That's why I was confused when phil added that to the tune he sent. What I wasn't sure of is with maf failed if that would make any difference. How does this look?

[JohnaPitt]

Here is a long log from tonight. I am going to try and get fueling a little better with all of this data. If anyone has any more pointers i'd appreciate it.

[jchambers]

After looking over log 5, at 16:40:11.5, I noticed it is going lean (15.9) at steady throttle and picking up knock 0.8 at 800 rpm and 1 mph. At 16:47:23, knock retard starts increasing around 3,900 rpms. I noticed you are running a 2 bar speed density os and the High Rpm Disable and Re-Enable speeds are set to 4,000 and 3,900 Rpm. You need to change the dynamic airflow High Rpm Disable and Re-Enable tables to 8,000 Disable and 7,900 Re-enable, so it references speed density all the time.

To me it looks like he's got a 3-bar MAP installed but has not applied the 2-bar SD OS upgrade. Anyone see it the same? Without the SD OS change, then he'll have to fail the MAF manually....correct?

[JohnaPitt]

I have since installed the 2-bar OS and re-worked the tune. Car is doing great

[JohnaPitt]

Maf has been failed since i began tuning it.