Intermittent 2000 RPM idle on warm/hot CIS-E engine

[urq]

... no BTDT specific to your model, but one thing I'd recommend you check 
for is whether or not the throttle body has a damper to keep it from 
snapping fully shut abruptly when you release the throttle.  This is 
something that was fairly common on manual tranny equipped cars in that time 
frame for emissions purposes.  If so, it may be sticking as it closes which 
keeps the throttle open just a little bit.  If that doesn't nail it, check 
the throttle body in general to make sure it isn't sticking, and the 
throttlecable and cruise control mechanism to see if one of them is 
sticking.  Also, verify that your ISV is operating ... if you can pinch off 
the air passage through the ISV while the idle is high, and you can slow the 
idle down by pinching the line off you know the ISV is at fault ... if not, 
look elsewhere.  The last thing that comes to my mind is to check to make 
sure the idle switch is functiuoning when the throttle is released ... I've 
seen a problem where the engine would idle high because the computer thought 
the throttle was depressed off the idle stop.

Steve B
San Jose, CA (USA)


>I have an 89 80q that seems to 'stick' at 2000 RPM but usually only when 
>the
> engine is mostly or all the way warmed up.  The problem actually gets 
> worse
> (or it sticks/surges longer) as the engine is warmer.
>
> If you are at a stop, around 900 RPM and touch the gas a little, and it 
> goes
> up to 1500 RPM, then it might just stay at 1500 for a while.  If you are
> slowing down and passing 2000, you might just stay at 2000 for a while.
> Later the RPM will drop to 900 and maybe some times it will surge up to 
> 2000
> for a while as you idle.  This usually only happens on warm/hot, though.