Two things to get idle correct. TPS voltage s/b .45-.75 volts AND your Idle Air Counts (IAC) should be around 20-40. The IAC count at 20-40 means the PCM is controlling idle speed, not the TB stop screw. If you can't get IAC AND voltage correct then you may have to slot the mounting holes in the TPS so you can get the correct voltage with the blades slightly cracked open enough to allow IAC to keep idle smooth. Bottom line adjust blade stop till IAC is correct, then if voltage is out of spec slot the TPS holes to get voltage in spec at correct IAC counts. Your balancing TB air flow and IAC air flow, since the IAC air goes through the intake plenums to reach each cylinder Vs the TB only letting air into the front, it's critical to have correct IAC valve operation for smooth idle, no split trims, and transition to higher RPM.
Good info, I already did all that. The problem was that unless the stop screw was adjusted out all the way holding the throttle open it would die, Ended up being a bad iacm. Replaced that and it was intermittent and would idle properly until you backed out and stopped at which point it wouldn't idle down or it would idle down too much.
I tinkered with the stop screw and the tps voltage with its running and my scantool in the enginebay making sure the tps was within range and the iac was between 20-50 and all was well but the engine rpm's were out of whack still and it takes forever to idle down.
Today I drove it around a bit and took about two turns off the idle screw to get the idle down after fixing the leak I found ( could have been intermittent)
It idled down to around 1000 on my tach (probably 950) and ran fine.
Until I backed out of the driveway and it started idling up.
Pulled back up and popped the hood. On a whim I wiggled the wires that go to the tps and what do you know the thing idled perfectly after that.
Going to fix that tomorrow and it should be about perfect except it still seems to take forever to idle down from 1500 takes about 2 seconds after I fully stop for it to idle down from there, And while rolling its alway at 1500.
Which is fine with me but doesn't seem normal.
Anyway I guess it was a combination of a bad IAC motor and a small intermittent vac leak and a bad wire on my tps sensor. ( which for some reason never showed up as a bad reading on the scanner)
I'm sure it will have a new set of issues tomorrow
LT1, Hotcam, PRW 1.6, 11:1, Ported Heads, T56, 3:23, Pro5.0
Hooker shorties, y-pipe & cat-back, 52mm tb, custom CAI elec wp
xegr smog catx aluminum ds Lca's & relocation brackets Adj. panhard pcmforless tuned