[Shotimes] High idle problems

[Zach Leahy]

Don,
 I am battling something similar on my 93 right now. I had the intake apart
and sent the runners off to Extrude Hone, and now have an idle problem with
the intake back together.
 So here is my symptoms and so far my actions.
 I get a stopped neutral idle of about 1750-2k rpm, and it does not want to
com back down when you blip the throttle ver quickly. It was even higher
than that in the 3k range.
 Problem #1 I had was that I installed the little warmup loop (which is
disconnected on my car now from the coolant) that is at the IAB backwards.
When you have it off and are not putting on hoses you can make this mistake
easily. The result was a vacuum leak and a partial contributor to my high
idle.
 Fixing that has brought my idle down from 3000 to about 2000. If I back out
the throttle stop screw I can get it to drop another 250-500 rpm. I know
that's not the correct way to adjust the idle, but it allows me to verify
that the air is either A) coming around the throttle plate through the IAB
or B) entering the intake unmetered after the throttle plate.
 I unplugged the IAB with the motor running, guess what, no change at all.
my theory is that my IAB is stuck in the open position. I sprayed it out
with some carb cleaner when I had the manifold out, as I did all the other
components, and found it was not dirty at all as I expected.
 Interesting to note, I have not plugged in the Tweecer to see wha the MAF
reading is (telling me whether the air is coming throug the MAF or not -
seems like it is as there is a lot of "sucking" noise through it) but the
PLX WBO2 is telling me the mix is pretty much 14.7 Either the O2s corrected
for the vacuum leak and upped the fuel or ther iar is realling going through
the MAF and is metered correctly and is getting the proper fuel delivery. I
support the latter theory which seems to indicate a stuck open IAB. I'm just
lazy and cheap and don't wanna replace it.
 I would say on the ATX that is not idling correctly to look for a vacuum
leak to begin with, listen for it in different places. Try the propane torch
trick if you need to try and locate it. Look for a missed vacuum line on the
intake.
 Z


On 10/11/05, Donald Mallinson <dmall@mwonline.net> wrote:
>
> Got a note from a member that is having problems with their 95 ATX SHO
> with high idle.
>
> It is at 1000 rpm at a stop in gear, and 1500-1700 in neutral.
>
> On light acceleration, the car gets to 35 mph at about 2000 rpm and
> doesn't want to shift to second gear.
>
> The owner recently replaced the IAC valve, TP sensor, VSS sensor, upper
> manifold gasket,
>
> Oxygen sensors, Cam Poisition sensor, and ECT sensor. He tried to find
> trouble codes but their are none in the computer.
>
> Any ideas?
>
> Don Mallinson
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