2006 Z06 Idle High

[Bossy70]

Tuning idle on a 2006 Corvette Z06 LS7. The car used to have a cam and some other mods but was supposed to be taken all the way back to stock (except exhaust). I took idle and airflow tables all the way back to stock repository LS7 tables but it consistently has a high idle condition. I have tried several things including knocking the base idle airflow minimum WAY down and even knocked the timing down to 6 degrees to try to get the idle rpm down. I found the one idle tunining thread but this car just doesn't respond as discussed.

Demand rpm is 675, but it wants to idle around 1000 rpm (above VSS/adaptive speed it idles a little lower at around 800 rpm).

It actually seems like a vacuum issue but I sprayed it down and couldn't find anything wrong. I unplugged the throttle and cycled ignition on a few times to see if it changed/reset anything, but it did not. My next thought was to take intake apart and make sure someone didn't drill the throttle blade or something.

Any thoughts?



Attached should be the tune and log where I start out rolling slow then come to a stop and idle raises. (DELETED because found hole in throttle body)

Note: on the log the wideband is not actually hooked up

[Bossy70]

Ok, I just pulled off the intake tube and they did put a hole in the throttle body blade.

[GHuggins]

Ok, I just pulled off the intake tube and they did put a hole in the throttle body blade.

??? Guessing the tune was just as big of a pile

[Bossy70]

HAHA, I didn't look at it much but most likely! The cammed motor had apparently blown up and everything had been replaced from what I understand.


Ok. So I sealed up the throttle blade and took all tables back to stock. Did better but still has same similar issue with idle at 0 mph.

Rolling/Neutral idle (above VSS/adaptive speed) is as demanded: ~700 rpm

But when I come to a stop it goes up to 1000 rpm. Nothing but dropping the throttle max percentage a good bit seems to lower it, but I don't want to have cold start issues.

I attached a very short datalog of a slow roll then coming to a stop. Please take a look and give me any input.

-Why does the demanded throttle position go up when I go below VSS?
-And why does it not try to pull timing during this adaptive to lower idle?
-Something just doesn't make sense to me.
-Tried lowering the base idle airflow min by 1 g/s from stock but didn't seem to bring it down any.



-Also one thing interesting I noticed when I still had the hole in the blade: I couldn't fill out the rest (right side) of the underspeed table because it seems to force the timing higher. They must know this because all those cells are zero above ~200 rpm error.

Z06idle_mod1.hpl

Z06stock_idle_params_mod1.hpt

[Kyle_Customizer]

Does the throttle body look like it has been ported?

[Bossy70]

I didn't notice if it had been (although I didn't look real close because I was so excited to find the hole... haha).

[Bossy70]

I adjusted the ETC Area Scaler up to 8100 and it didn't seen to effect the idle.

I guess I will slowly decrease the max throttle area percentage from 2.37% down again until it idles ok. And then hope it still does ok with cold starts (because I will probably have to lower it to 1% or below again).

[GHuggins]

You should be able to go down around 1.9ish and still be somewhat OK... Really sounds like you still have something else at play though...

[Bossy70]

I feel like something else is going on too but not sure what. I basically have to lower percentage max to 0.8 to get idle down. BUT, it actually uses underspeed timing advance and then seems to have no idle adjustment capability). Crazy. The timing actually advances as I get closer to the desired idle speed. It actually adds the underspeed advance timing and makes it even harder to get there, what that also does is keeps the timing advanced all the time and then it has no timing underspeed adjustment capability left.

I think there is something wrong with the throttle body. I hiked up the idle airflow final minimum table by 5 g/s and it didn't cause it to idle up. And if I take out adaptive spark I basically have no idle control.

This is so weird to me. I have never had this issue.

[07GTS]

i had an issue where mine wouldn't go lower unless i used the max percent to lower it but that killed cold start rpm, i found it was my integral table and yours looks quite low compared to mine and just for a test u could even multiply yours by 10 to get the lower error numbers higher see if it helps if not just change it back