Raising Idle in an A4.....how??
03-31-2004, 11:01 PM
#1
Raising Idle in an A4.....how?? I know the hole in the TB can be drilled to raise the idle, but won't the IAC valve compensate for that and try to bring the idle back down?? Then sooner or later the IAC would be maxed out and the idle would stay up if the hole was big enough...but then wouldn't that throw a code?
Also, if I replace the "idle screw" with a longer one so I can get more adjustment and crank the idle up to about 750...the TPS would move and the IAC would think you have your foot on the gas a little and would not try to bring the idle back down...correct? Would this be a better way of doing it??
My A4 idles fine in park with the TR224, but it gets a little choppy in gear when stopped, so I'd like to bring it up just a bit.
Thanks,
Mike
Also, if I replace the "idle screw" with a longer one so I can get more adjustment and crank the idle up to about 750...the TPS would move and the IAC would think you have your foot on the gas a little and would not try to bring the idle back down...correct? Would this be a better way of doing it??
My A4 idles fine in park with the TR224, but it gets a little choppy in gear when stopped, so I'd like to bring it up just a bit.
Thanks,
Mike
03-31-2004, 11:47 PM
#2
You really need to have the PCM tuned. The commanded idle rpm must be raised. It can be done temporarily with either a Tech 2 scan tool or EFILive 5. To make permanent changes will require LS1 Edit.
Adjusting the throttle stop screw will effect the IAC control. It can be used effectively to adjust the IACs to a desired 30 counts at idle with the a/c off. Turning off and back on the ignition key resets the throttle stop zero position. The large butterfly of the LS1 throttle body needs only one or two turns to swing the IACs into the desired operating range. No need to drill a larger hole in the t/b. The pcm will need some driving time to learn the new settings, so don't just "driveway" tune the idle.
Hope this helps,
Richard
Adjusting the throttle stop screw will effect the IAC control. It can be used effectively to adjust the IACs to a desired 30 counts at idle with the a/c off. Turning off and back on the ignition key resets the throttle stop zero position. The large butterfly of the LS1 throttle body needs only one or two turns to swing the IACs into the desired operating range. No need to drill a larger hole in the t/b. The pcm will need some driving time to learn the new settings, so don't just "driveway" tune the idle.
Hope this helps,
Richard
04-01-2004, 09:49 AM
#4
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You would have to make more air bypass the
throttle blade, and that will **** off the IAC
control loop. You can drill the hole but it's
tough to undrill it. I've thought about adding
an idle air bypass screw-adjusted passage
which (if done right) could be at least set to
zero once you get programmed. That's just
drill and tap work (as long as you don't screw
up). But the PCM is a control freak and will
do its best to fight you, until you give it the
father-and-son chat.
throttle blade, and that will **** off the IAC
control loop. You can drill the hole but it's
tough to undrill it. I've thought about adding
an idle air bypass screw-adjusted passage
which (if done right) could be at least set to
zero once you get programmed. That's just
drill and tap work (as long as you don't screw
up). But the PCM is a control freak and will
do its best to fight you, until you give it the
father-and-son chat.
