2005 C6 LS2 Idle Speed Drops When Stopping

[dgcarver]

Several years ago I installed a supercharger, extended MAP, long tube headers, injectors, etc. and had my 2005 LS2 dyno tuned using HP Tuners. Ever since then when I pull up to a stop light and start slowing down the rpms will dip down just before I stop and then come back up. Sometimes when I back up and stop it will die also. When the ambient temperature is above about 80 sometimes it will dip to zero and die, requiring me to brake and gas at the same time to keep it from dying. I know it has to be something in the tune that is cutting back the fuel while coasting down below about 5 mph. I've tried coasting down in neutral (I have a 6 speed) and in gear both and it still does the same. I've used the software to compare my tune with the stock tune, but am not smart enough to recognize where the error might be. If someone could take a quick look and tell me what is probably obvious, I would be very grateful! Other than the idle problem, it runs very well.


LG2-5 2 bar-dgc01.hpt Stock Tune.hpt

[5FDP]

Couple questions.

Is this a speed density only with no MAF sensor?

I ask because there are some pretty weird settings going on. The MAF fail high is lowered to 8,000hz, the MAF dtc's have been set to no error reported and you MAF curve is whacked if you are.

If this is a speed density tune you need to set the high fail to 2hz, low fail to 1hz and the 3 MAF dtc's to fail on first error. Who ever set this tune up surely has no clue what they are doing.

How large are your injectors?

Why is the PE table stupidly rich? It commanding anywhere from 11.0 all the way down to 8.5 AFR at 6,000+ rpm. Someone just raped the PE table to get fueling in place instead of actually tuning the VE correctly.

[5FDP]

It's hard to believe that it even runs okay with how bad this tune looks.

[dgcarver]

It's hard to believe that it even runs okay with how bad this tune looks.

It's been awhile since I installed it all (I think it was 2007 or 2008), but I did change out the MAP sensor to one that is 2X if I remember right? The injectors were Siemens if I remember right. Don't remember the capacity. The tune was done by LG Motorsports in Wylie, TX on their dyno using my software and laptop. To be honest, I'm not sure how many they had done previously using HP Tuners. Performance wise, it runs very well so I don't think it is off very much other than the problem with the idle. Neglecting the settings for performance, did you notice anything that would cause the idle problem?

Thanks for you help.

[GHuggins]

5fdp is right. You should probably have it tuned by a better shop. That thing has lots of problems. But just for idle, you can probably add 1.5ish to the min air table and go from there.