Mechanics

HIGH AND LOW IDLE

2003 Saturn Ion

Computer problem
2003 Saturn Ion 4 cyl Two Wheel Drive Automatic 101000 miles

2003 Saturn Ion 2 automatic 101,000 miles
Here is some back story…Right before Christmas I was pulling out of a parking lot and my car began to idle very high, almost driving on its own. I drove it a few blocks and then when I got to a stop sign it would not come to a complete stop because of the very high idle. I put the car in park (I didn’t know I shouldn’t do that) and it went up to 4000 RPMS and held there. I called my dad and he told me to be really careful and drive it the 5 blocks to work. I did and when I got there I had to drive around the parking lot for 30 mins because it wouldn’t come down. I called my friend and he told me to put it in neutral and then shut it off. It was ok when I went back out to go home. It didn’t do it again for about a week and then that time it I was on the freeway and it locked up going 60 mph and wouldn’t come down…then there was a “pop” sound and it levels out to normal. The next day I bought and idle air control valve and drove to my parent’s house to have my dad replace it. On the way there when coming to a stop light the idle dropped to 500 rpm’s and shuddered like it was going to stall. My dad changed the IAC and the high idle problem went away but the low idle continued. I have taken it to 3 separate mechanics…the last one was able to duplicate the problem and they said that the computer needed to be reprogrammed and that the problem should be fixed. After 155.00 charge for the computer and new spark plugs it ran fine for 3 days and then it started it idle low again. Then a few more days went by and when turning a corner the idle dropped to zero and the car stalled. This happened twice within a week. I took it back to the shop and they had it for 3 days and couldn’t find anything. And then this is what happened this morning on my way to taking my son to school. Something told me this morning to take the side streets because it is slick and the car was going to mess up…and low and behold it did, it was running high…not too bad around 1250-1500 rpm’s but since it was about 25 out that didn’t surprise me but when I stopped at a stop sign I thought I would throw it in neutral because that usually gets it to level out…so I did and all of a sudden it shot up to 3k and held there! So I turned it off put it in park, gave it a few seconds and then turned it back on…again it shot up to 3k but then it came down to 2500 and held…. So then out of no where there was a “pop” of some sort (similar to the one that happened when I was on the freeway) and then it immediately dropped to 500 and then leveled off at a perfect 750 and ran fine the rest of the way to school and back to work…I was obviously a pop of air or something similar…so what I’m thinking is a air leak, or a clogged hose or filter…. Which would make sense why it’s so intermittent because there is buildup and it runs poor then the “pop” clears it and it’s find for a little while… ok I know you don’t know much about cars but I had to get this all out…. Do you think any of that makes sense or adds up?
Avatar
Kristymk2007
February 16, 2010.



Wow, thanks for the story Kristy, a little back ground info always helps. It does sound like an IAC issue, or something along those lines. Here's a few thoughts.
I have seen the thottle plate itself getting stuck in the thottle body, which is also where the IAC is located. I have also seen a build up of moisture in the thottle body causeing an iceing condition that could result in a high idle, and I have also seen a bad TPS sensor cause the same issues.
I would have some-one take a look at the thottle body and check for binding within the thottle plate or maybe a moisture build up, and give it a good cleaniing while they have it off. It is also possible that when your father replaced the IAC that he didn't clean out the port that it goes into and it may be getting stuck in there, try taking it out again and cleaning out the port. As far as the TPS goes, some-one would have to have a diagnostic tool hooked up and see the TPS readings while the problem is occuring.
So have some-one remove the thottle body, remove the IAC and give it a good cleaning and see if that rectifies the problem. Let me know how you make out with that.

Tiny
Basstech
Feb 16, 2010.
Just one more thought. Can you take a look at the accelerator pedal itself and make sure that there isn't any thing obstructing it like the flloor mats or anything. That snapping sound you hear could be the pedal releaseing from the mat. It's been known to happen. Good luck

Tiny
Basstech
Feb 17, 2010.
Thanks for the advice. I will print your response and give it to the shop, they are at a loss. No there isn't anything down there, I purposely removed the mat to make sure that wasn't the problem. I will be sure to let you know what I find out. Thank!

Tiny
Kristymk2007
Feb 17, 2010.