Timing lower than commanded 2011 CTS-V

[mourat]

Hey everyone,

I should probably post my tune off the laptop here. It's an automatic and there is zero knock when logging. TQ MGMNT spark is not being enabled except in between shifts. I've checked my IAT/ECT all those tables and none of them are being triggered (I am in the 0 add areas).

Somehow I'm commanding 13 but getting 10 and looked everywhere, it's my buddie's car. I've tuned a 2013 ZL1 Manual and this phenomenon was not present. The timing is fairly accurate to commanded in 2nd gear. then third gear you can see there is less timing. Seems like there is another table that can tell which gear you're in and reduces timing based on which gear the trans is in.

MAP/RPM values all same between 2nd and third gear yet timing is 2-3 degrees lower in taller gears.

Thanks,
Matt

[schpenxel]

Log literally every channel or parameter there is for timing, you'll find one of them that's doing it most likely

And post log/tune of course

[mourat]

Thanks, I put the pids in there last night and will try out today but honestly thinking it might be a table that lowers timing by gear. I will report back but it wouldn't be a bad idea of GM to do that. Taller gears you stay in the same load range for longer. IE you can get away with more timing in 1st gear than 6th cuz you don't spend much time in those cells to start knocking.

[GHuggins]

It's most likely just IAT or something - make sure your logging IAT 1 and 2 for the log... Then as Carson said, log all of the timing parameters that you can - this should lead you right to what's going on...

Also make sure your knock is set to (+) and not averaging... You might see something a little better that way as well

[mourat]

Where is the (+) setting for knock instead of averaging ? Sorry wanted to ask while you're active on the forum.

Edit. I don't think knock averaging is an option on this calibration file. According to HPT instructions should be under KR sensors.

I'll log IAT1 +2 totally forgot about that ohh dear so embarrassing

[schpenxel]

In graphs.. up at the top it has a + - A L C

+ shows max
- shows lowest
a average
l last
c count (number of hits in each cell)

[mowton]

Two additional recommendations is to log Dynamic Airflow and create a new Dynamic Cylinder Airmass parameter using the MAF Airmass equation (in tools>Math Parameters>Cylinder Airmass) as a base and swapping in the Dynamic Airflow parameter for the MAF and creating (copy/paste) a new user defined.....this is where the PCM is actually going at the end of the day. Secondly, log Knock Learn and it will tell you if you are biasing toward the low octane table.....

Ed M

[schpenxel]

I agree on using dynamic airflow for g/cyl

Actually, I wonder if we can get HPT to include that one in the list that comes with it..

[Aaron407]

Two additional recommendations is to log Dynamic Airflow and create a new Dynamic Cylinder Airmass parameter using the MAF Airmass equation (in tools>Math Parameters>Cylinder Airmass) as a base and swapping in the Dynamic Airflow parameter for the MAF and creating (copy/paste) a new user defined.....this is where the PCM is actually going at the end of the day. Secondly, log Knock Learn and it will tell you if you are biasing toward the low octane table.....

Ed M

Agree with this, especially ensuring that you're reading the correct cylinder airmass to reference the timing cells. One way to rule out the knock learn would be to temporarily copy your high octane timing table to your low octane table so it doesn't learn down. Although I don't have my tuning laptop handy right now, I believe there is also a timing modifier table based on commanded AFR.

[schpenxel]

There is

[mourat]

Lol yes def not on averaging

All resolved it was a stupid mistake I panicked for no reason and it was 3am lol. It was in fact just IAT 2 I should of been logging not IAT 1 no clue how I made that mistake but this is why you guys are great and here to remind me of the little things I tend to take for granted and forget.

I should have known when IAT was going down while I was at WOT. Positive displacement blowers usually rise in IAT temps with time at WOT that should have been my first clue.

Anywho it was just IAT 2 going into the subtract zone. I was looking at IAT 1.

Thanks again!

[SultanHassanMasTuning]

IAT 1 IAT 2 that would do it