Banish 50% Scaled Tune TBSS LS2 E40 Problem

[vetteboy2k]

Having a problem with a scaled tune for a Maggie TVS 1900. TBSS is perfect except for when A/C is turned on.

Smoke tested and no vacuum leak or anything. A/C off truck runs perfectly. Once A/C is turned on the airflow goes way too high and idle runs away and rpms hang and tough to even stop the truck.

I have halved B1825 and B1826 for A/C compensation and have even went to the extreme and made those -32 g/s with no change in idle.

There must be additional A/C Idle airflow tables not available to scale causing the issue.

Had to scale as to avoid maxing the maf 512 g/s limit and injector 7.9999 g/s limit

Any ideas or additional tables Ross or Paul to add to the calibration Operating System 12606494

[vetteboy2k]

Also are there any Throttle Cracker or Throttle Follower airflow tables? When halving these tunes these airflow tables are important to have access to.

[GMPX]

Mmm, Troy, E40 was not even on the radar this year, I'll see what others suggest, I'm sure you aren't the first to tune a combo like this.

[vetteboy2k]

Yea, the E40 was such a short run of engine controllers used anyway. Going to check if there are any newer OS available on TIS for the 2006 TBSS and see if that helps at all.

[ScarabEpic22]

If you cant get it sorted quickly, contact LeftCoast32 aka Joe or Alvin at PCM4Less. They've both done a bunch of engine builds with TBSSs, mines an 08 E67 so I cant help too much. :(

[vetteboy2k]

I know Joe pretty well, and am friends with Matt at TuneTime Performance who has tuned tons of TBSS's, I will track this down. Matt and I were talking about it over memorial day bbq's and that's when we thought it might have something to do with the E40 controller or operating system. Was thinking had to be airflow tables unseen as its only when A/C is on.

Matt has halved other Maggie TBSS's with other PCM's and no issue. I have also tried 2 different Truck 90mm Throttle Bodies and trying a car 90mm Throttle Body, and they all react the same.

[eficalibrator]

This sounds exactly like what you're saying: another table that isn't mapped in EFIlive, yet is still commanding an unscaled g/s target. Does it learn it out over time? You might try opening up the allowable idle airflow integrator limits to give it the ability to learn down to the new (scaled) target. It won't take effect immediately, but it might make it tolerable if you're not able to access the table that is the fundamental issue here.

[vetteboy2k]

Hi Greg,

Its not learning it out unfortunately, and I don't see tables in the E40 for allowable integrator limits either. I know they are there in the earlier PCM's but don't see them in the E40 Calibration.

Maybe something I can do with these tables? Reduce the allowable max idle percentage?

{B1651} Max Idle Area 1 2.3743 %
{B1652} Max Idle Area 2 2.3743 %
{B1701} Airflow Area Conversion Max 8191.0 mm2
{B1702} Airflow Area Conversion Min 5.0 mm2

[vetteboy2k]

Was able to fix the problem with the Max Idle Area 1 & 2. I reduced to 1% for both and the issue has gone away. May help someone else in the future. Thanks for the help guys, got my brain thinking harder to nail this problem down!

Probably just a bandaid fix and not a proper scaling procedure, but it did work and car drives like stock now.