Hello all, I am having a problem with my car idling up and down and at too high a rev range. I took the car out after having been garaged for several months and it was idling normally. When I went to put gas in it on the drive back the CEL came on and the car started idling like this. Cleared ECU, didn't touch anything on the car at all. I have searched the forum but can't find any posts that describe my exact symptoms. I have checked for vacuum hoses popped off and tried adjusting the air adjusting screw on the throttle body. This had no effect. I will try to embed a video of it here, any help would be appreciated.

 

When driving the car, does it buck at partial throttle? There was a service bulletin that was put out concerning grounding points in the engine bay. The poor quality of the grounds results in high resistance that can affect the fuel control system. I had the same issue a while back, and after replacing my grounds the issue was resolved. My car would buck hard at all rpm ranges at low load and idle, but operated fine under WOT. It's a cheap place to start, and it should be done regardless. Make sure that you sand off any paint at the grounding point though to ensure a good ground contact, and battery cables make for a good/cheap alternative to more expensive kits . I've attached the service bulletin.

 

Thanks for the response, no, it doesn't buck at all. Runs perfectly fine when being driven.

 

Bump, can anyone help?

 

i honestly use to have this, and my fix was because a bunch of vacuum lines in the "rats nest" where broken due to heat. start there

 

Like he said, check vacuum lines and check your map sensor, connections and the nipple were the hose connects to it. Check on that.

Edgar

 

Thanks for the responses, I have had vacuum hoses replaced although it was several years ago. I did look at them and didn't see any popped off or loose. I will check again. Anyone else have any ideas?

 

Bump

 

Does it do it all the time?? Or only when the car is warmed up??

Do you know what the Wax Rod/fast idle cam is?? It is located on the throttle body inbetween the fire wall and the throttle body. When the rod goes bad or no coolant flows through the throttle body to warm the rod, a fast bouncing idle can occur. You can push it with you finger and see if you can manually dis-engauge it.

I took a picture of it, as its easy to see on my car because I have a bunch of crap removed. Its the dark green/greyish horizotal piece with the screw that goes verticaly just to the left of the GRAY 3 wire connector(tps). You should be able to push it down. Try that and see if it does anything.

 

Thanks, this is great info and will use (mine actually only has 1 grounding strap on it at the moment.)

 

Thanks Seandizzie, the car idles like this probably within 30 seconds of being started. Not sure if I am getting any coolant to the TB, I guess I could look at that too. Thanks again.

 

Not a fix,bput the wax rod thing can be set open, kinda a rigged fix

 

Ok, thanks.

 

did you ever find a fix to this? mine does this when coming to a stop but only 2 or 3 times and then goes back to idling normal.

 

idle surging is caused by the ECU dumping timing, because your idle is too high out of range. it can be exacerbated by a TPS out of adjustment.

stuck thermowax
air bleed screw set out too far
idle set screw set too high
TPS out of range


less prominent would be a faulty ISC solenoid.

 

I just recently had my TPS adjusted and my idle adjusted (it started doing this after that) Should I have it adjusted again? Or start looking into other areas.

 

my car does this when coming to a stop also, is there a write up for what to look for?

 

turn your curb idle screw out 1/8 turn and your air screw under the throttle body 1/4 turn in and see what happens.

 

Did we ever figure out what the problem was? Mine did the same thing and I forgot how I fixed it :S

 

Mine was doing the same thing after removing / replacing the UIM. It was because I put the metal throttle body gasket in backwards. It's indented on one side, and I didn't notice the upper corners are different, so the indentation was facing the wrong way (DOH!). It allowed too much air to get past the ISC passage in the throttle body, so when the ISC was working the idle bounced around. Unplugging the ISC cable would stop the hunting but it wasn't an issue with the ISC solenoid, just the gasket backwards. Just something else to think about if you replaced the throttle body gasket and then the issue starts.

 

Anyone have a photo of these? I'm not sure which is which...

 

Bump

 

The below is really good advice if you have a surging idle. I would start by checking your air bleed screw (unless if you didn't mess with it), then TPS, then clean your ISC. You shouldn't mess with any of the other screws. There is a lot on all of these if you search. Also, if you have a PFC, they don't idle that great.

 

Bringing this back since now I am having a surging idle issue about 30 seconds after starting the car. What we know as of now:

1. Car was idling fine prior to removal of UIM, TB and elbow for cleaning and gasket replacement. Which obviously makes me think this is self induced.
2. I tried to disengage the wax rod but am having no luck. The mount beneath the rod is able to be rotated is that normal?
3. I have replaced, cleaned and sanded down to bare metal the grounding points outlined in the service bulletin.
4. Temps are fine on the car and it runs normal but starts the surging idle when car is stopped.
5. I have not adjusted any screws or TPS yet.
6. Lower throttle cable seems a bit loose

I linked the video as well

 

Just flipped the TB gasket no change.