Don't know if anyone remembers my post from August. Basically the surging at idle thing; surging when accelerating; unable to accelerate smoothly.
Several people suggested cleaning the IAC/IAB/Idle Air Bypass Valve. Well, I finally took it off and cleaned it with some carb cleaner, and guess what - problem is completely gone. No more surging under any condition, with or without AC on.
Thanks to all who responded on this! John
OK, so I started up my car today, without the AC on, and it did the 2500rpm > rev thing!
>
> It started fine, idled for a few seconds, then revved to 2500, held for
> about 4 seconds, then dropped back to 1000.
>
> So, if it's doing this with or without the AC on, where should I look for > the problem?
>
> Thanks,
> John
> My 93 GT (manual) is doing some weird stuff only with the AC on. >
> Firstly: When I start it up in the morning, it starts fine, and idles fine
> for a few seconds, then revs up to about 2500 rpm, holds there for 3 or 4
> seconds, then drops back to 1000.
>
> Secondly: Under acceleration, it is impossible to get a precise throttle
> response. If I try to accelerate slowly and smoothly thru first gear, it
> will go smooth up to about 2500, after which it acts as if I have suddenly
> stomped on the pedal. Then when I completely let off the pedal, it takes it
> a second or two before it stops accelerating. It acts as if I still have my
> foot on the pedal.
>
> Third and finally: At cruising speed (70-75mph) it does not want to just
> maintain a speed. It wants to be either speeding up or slowing down. If I
> set the cruise control, it will oscillate between "gas on" and "gas off". >
> Note that none of these conditions exist when the AC is off!
>
> Any ideas? Thanks,
> John
>
>