Hey all, finally got my combo going.
I have an 03 Marauder, Terminator Longblock and 3.4/Crusher.

I made a base tune for it and everything is ok except for the idle.
No matter what I do, it idles about 400-600rpm's above the commanded idle rpm in the tune. I am running a terminator IAC and have loaded the correct values into the tune.
I did notice this:
When I start the car, it seems to idle at the correct rpm, but as a short amount of time goes by, the rpm's raise steadily. After about 1-2 minutes, the idle is around 1300 in park and stays there.
Ive checked for vacuum leaks and have found none. Im using the stock SC gasket with Aenerobic gasket maker on both sides. I also used this for the Crusher inlet surfaces.
It is making about 13-15 inches of vacuum at idle, and when I goose it, it goes to 20 after I let off.

Any issues Im having sound familiar?
Thanks in advance!

EDIT: For got to mention unplugging the IAC's electrical connector does not affect the idle at ALL

Great question but I personally don't know the answer as I'm not a tuner. Let me see if I can get some tuners to join and help you out.

Thanks, Jared

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Have you tried to adjust your Idle Maf tables in Neutral, have you checked your TPS voltage? What are you using for tuning software. Also check the throttle body, push on it while car is running, if idle calms down, it may need to just wear in a little or put a really heavy duty TB spring on it.

This is the exact info and suggestions I am looking for.
I have SCT tuning, the TPS voltage is .98 and yes I pushed in on the TB to no avail.

This is most likely an easy fix for a professional, but I have a 2 hour ride to the actual dyno and do NOT have a trailer. I just want everything to be 'almost perfect' before the tune....Ive wasted too much money in the past not making sure everything was spot on.

I never adjusted the table for compensating for breathers on both valve covers.... maybe I should look there????

I see justin from VMP just signed up. Bet he's got the perfect answer.

Is it a custom tune someone made for you? I only do Diablo here for now. Where are you located?

No, I made it.
Im in Indiana.

I would just pay someone over the phone to get you a mail order tune & get you a startup file, then take it to a dyno & have it custom tuned before you hurt something. I have guys travel from 4 hours away for tunes, its not worth all the money you have spent not to get it done right. There are alot of sct guys out there to help you Justin at VMP, Rick at Amazon Tuning, Doug At Bamachips, & the list goes one.

I am also having same issue breathers in valve covers and everything with 3.4 crusher did you ever resolve this issue???