RPM's dip below idle when clutch is pushed in at high RPM's, cooler weather...

[slammin86]

I have a 04 GTO. It is a 6 speed with a ls1 that has forged internals and has been bored over to a 347. It has a 229/234 .612/.600 111 lsa cam, and it is installed at 107. The car has stock 243 heads, kooks longtubes w/ cats, a ShaneR ported stock TB, and an underdrive pulley.

Here is my problem. With the weather getting cooler, I have noticed that if I am driving at lets say 4th gear at 4000 rpm, and push the clutch in, the car will idle down to about 400 rpm, then bounce up to 1200, then stabilize at 800-850. I have about 2500 miles on this motor so far, and it seems to have started doing this with the weather change. Maybe the weather change is coincidental, I don't know for sure.

I am attaching a tune, I am deleting out the injector data because I am unsure if I can post that portion. I have the injector data off of Greg's DVD.

I have searched though this forum, and found a lot of info on tuning idle, but it seems that I have different tables, or the tables are named differently in a GTO.

Any help would be greatly appreciated. If someone could point me in the right direction and give me some tips on what to change that would be great.

[C5 2000]

IAT Spark Advance need work to take some spark out. Also i would Work on the ECT Spark Correction-Add.. zero out all the mimuses the (in the Middle area(0.16,0.44).

[Frost]

You need more throttle cracker airflow there to catch the car.

I made a minor change to your table in the area that you describe.

[slammin86]

IAT Spark Advance need work to take some spark out. Also i would Work on the ECT Spark Correction-Add.. zero out all the mimuses the (in the Middle area(0.16,0.44).

On the ECT spark table, I have already zeroed out 2 more rows than the stock tune because of my 160 degree thermostat. The car normally runs at 175 to 185. The iat's under most circumstances are about 10 to 15 degrees above ambient. Why do I need to take some more out of that table? I have already shifted it pretty heavily from stock.

You need more throttle cracker airflow there to catch the car.

I made a minor change to your table in the area that you describe.

Thank you, I will try that. So the throttle cracker airflow vs rpm vs speed is the table I should be looking at to solve this problem? The higher the number, the more the tb blade is open? So the changes you made should allow the rpm's to "catch" themselves as they fall and maybe not dip so hard?

[Frost]

Your car is an IAC car. The TC adds airflow through the IAC when the car is moving.

On the vettes, it does not work when the clutch is in (PITA) and it may respond the same on yours. You will have to try it and see.

[slammin86]

Your car is an IAC car. The TC adds airflow through the IAC when the car is moving.

On the vettes, it does not work when the clutch is in (PITA) and it may respond the same on yours. You will have to try it and see.

I have never done any idle configs or anything on my car. I want to try the russ k config before I change anything else to see if that solves my problems, but cannot figure out how.

I made a thread about this.

http://www.hptuners.com/forum/showthread.php?t=26204

Hopefully I can get that lined out then move onto this.

[slammin86]

So I ran the idle russ k idle config today. I kept the fans shut off, and let it idle up to about 225.

Afterwards I went for a drive. It took a little bit for the car to stay running on its own. I figured it had to re learn the idle. That settled down and I started a new scan.

After hard throttle runs, and a few times under moderate throttle, the rpm's dropped below idle after pushing in the clutch.

Attached is my config, and my log. Do you think I should add numbers to the 400 and 1000 columns of the Throttle cracker airflow vs rpm vs speed? If so, how much should I try adding?

[Gh0st]

Frost is right.

I had very good results with reducing the idle trim boundaries or removing them altogether too.

[slammin86]

Frost is right.

I had very good results with reducing the idle trim boundaries or removing them altogether too.

Do you mean zeroing out the throttle cracker table?