STI Diagnostic connector connected - engine performance

[Jesse]

How does you engine perform when you ground the STI Diagnostic connector? Do you notice any difference?

I am trying to diagnose some issues and my motor runs poor normally, but when I connect the STI connector it becomes horrendous and will stall quickly. I don't know if this is normal.

[gergorian]

I think when you ground the pin the pcm defaults to base timing and a base fuel table, pretty much constant open loop.

[Jesse]

But does that translate into "run poorly"?

[bhazard]

Your ignition timing is probably retarded too far

[gergorian]

But does that translate into "run poorly"?

It can. Like bhazard said it could be your ign timing. If your base timing is off then it can run poorly because the computer adds/ subracts timing on top of base to compensate but it can only go so far. Then when you jump sti and gnd it goes to base timing and if it is off it can run really bad.

[defprun]

Mines grounded because otherwise my car idles at 1200...

[gergorian]

Mines grounded because otherwise my car idles at 1200...

Sounds like you have a short to ground on your IAC or a bad IAC. Why not just remove it and use the throttle blade adjustment screw to set idle? Your car will run alot better if you dont have the pins jumped.

[defprun]

With the IAC disconnected it wont run

[defprun]

How much adjustment to the screw would be required?

[defprun]

With my IAC cleaned the idle isnt so bad (1-1.2k) now with the STI ungrounded not too mention the performance has increased a bit PLUS it doesnt idle like it has a vaccuum leak anymore. Guess the IAC just needs a proper carb cleaner bath overnight.