Hi
Just got me a 89 SIdekick and the idle is jumping from about 1200 rpm to 2100 rpm, it surges. Does it when its cold and when it warms up. Any ideas what it could be, I have been told it may be the engine heat sensor?

Thanks
Eaon

The 89' has a "kicker" on the throttle body
that when the engine is cold kicks the throttle
open a little to give you a high idle.

If this is kicking on and off, it could affect the
idle speed. I have always had too high idle when
cold and erratic idle at times, I think it's the way
the throttle body was designed, I think there is a
screw to addjust the idle speed that the kicker gives,
try backing this off some, the other screw adjusts
the regular warm idle speed, it does not contact
the kicker, so you should be able to tell which one
you need to addjust.

I think the kicker is a piece of junk, it's vacuum opperated
and if you want you can adjust the thing so it doesn't do hardly
anything, and just run from the regular idle mostly.

there is two little electric opperated valves at the front of
the engine on the intake side, they got hoses running to them,
those might be the problem too, mine got both vent covers
broken off, (bonehead dealer mechanics) but I don't know
what they do, or if they are needed, seems to me one of
them is the vacuum line that controls the kicker too.

Check the vacuum lines for proper conection and placement,
I know all of mine probably need replaced, but I don't have
any idle problems I can't live with.

what he said
Also check the EGR valve be sure it's seated. remove the vacume hose and rap it a couple of time with a light hammer or a wrench, rachet or what ever you got handy. see if that settles it down.

 If the EGR is not seated it wil cause a vacume leak (on TBI that's = to opening the throttle)  and also makes the kicker go crazy.

Check your TPS with a meter, it sounds like that might be the problem.

Mac

My 89 has a similar problem. It will idle at 700 for a for a minute or two, then the RPM bounces between 700 and 1400.  

Turning off the head lights/heater fan calms it down sometimes.

Is there something that is supposed to adjust the idle up when you turn on the lights that might be going bad?/

I always had a different sound comming from the
EFI system when I turned on the Lights, like an
idle speed increase, sounds like a low fast light
thud sound, how would you describe the sound ??
similar ??

a weak battery can cause cause idle sped flucuation (700-1500rpn)
when I was an auto tech I had a sidekick in with idle speed issues. I couldent tell him absoulty for sure a battery would fix it cuz it tested low but still in speck . Another shop went out on a limb , put in a battery and that fixed it


Idle speeds over 2,000 rpm? I don't think a weak battery will cause that.  
vacume leaks or improper TPS adjustment can though.

Definitely related to running the lights and/or heater.

Today I turned off lights and heater as I was putzing through the lights downtown. Idle was stable.

Turned the lights and heater on a couple blocks before I got to work, idle started bouncing. Turned lights and heater off, it stopped.

Did not hear a thud sound, idle runs up, then suddenly cuts outs and drops down.

Will check battery and grounds.

My 90 does the same thing with the idle bouncing around.  If I dial it up to 1300 rpm minimum it doesn't jump around, but that is a little high for normal running.  Also occasionaly when warmed up it will want to dip below 1000 rpm and die.  When that happens it is hard to start for a few minutes.

It really sounds like your TPS pull it off and clean the inside up with some contact cleaner from Radio Shack, and set the TPS back up with your multimeter and you should be set to go.


Mac

Mac, does the FSM tell how to do this? If not could you give me more details.
1- Where the TPS is located
2- How to 'set it up' with a mulit meter

Thanks,
Zig

Battery Advice was good.

Clamp on positive terminal was loose. After tightening clamp, idle is stable after warmup.

Still bounces while warming up. But not as harsh.

My Kick also make kind of a thumping sound when it ildes at first, then it goes away once it warms up but comes back again when I get the RPMs over 2200 or so. I think I figured it that it makes it when I press the pedal past a certain point.  I havent figure out what it is and it ruins okay so I dont fret about it. I also dont have the stock air box on anymore so mabey it is just some sound coming out the aluminum intake tube that goes over the motor.



Jacob

Battery advice is proving to be even better!

Now that I have had a chance to get a charge on the battery, the bounce seems to be gone even when it is warming up.

Mac, does the FSM tell how to do this? If not could you give me more details.
1- Where the TPS is located
2- How to 'set it up' with a mulit meter

Thanks,
Zig

The Chilton's manual tells how.

Don, y'all
.