98 GTS Intermittent High Idle ?

[v10enomous]

My 98 GTS with 35k miles which only has the K&N Intake kit and cat delete is idling high around the 1,200 mark instead of it's usual 750 or so intermittently about half the time.

Any idea what it could be ?

[ICPREY]

May want to look at the Idle Air Controller and possibly clean it.

[fastrs2.5]

Vacuum leaks can raise idle

[v10enomous]

So yesterday I went to take the car out and when I took the cover off the door wasn't all the way shut and even though the trickle charger was on the battery was so dead that even the dash lights wouldn't come on. So I jumped the car with the jump feature on my regular battery charger and took the car out to charge up the battery and after about a mile it would stall when coasting and restart when I let the clutch out. So I took it back and charged it fully overnight on 2amp until charger read full.

So I just took the car out and it ran fine for about 10 miles and then started the stalling issue again with no sign of the intermittent high idle. I pulled it back in the garage and shut it off and then almost immediately restarted it. The cranking was very strong and it seemed to be idling normally for several minutes so I shut it off.

How do I clean the air idle controller ?

Any other thoughts...

[Bugman Jeff]

How do I clean the air idle controller ?

Any other thoughts...

There's a brief description of cleaning the IAC here:
http://driveviper.com/forums/threads...ll=1#post49843

Also, be careful using the jump function on your charger to start the car. There have been reports of frying the computer because of the voltage spikes some charges put out on jump. If you have to jump start it, it's always better to do it car to car with jumper cables. That way you can be sure you won't over-volt the PCM.

[RTTTTed]

Jeff is correct. The jump start feature is dangerous unless your battery is in good enough shape to use the amperage being put out by the charger. If the battery can handle the extra juice cause it's too dead ... the ECU is sensitive.

Car often won't idle when the battery voltage is "off". If your battery isn't already new, it's probably a good idea to replace it anyway.

[swexlin]

I know 3 years ago, my 03 would start, then idle like crap for a couple seconds, then die. New battery solved it. These cars are not tolerant of weak batteries. I'll bet you lunch it's as simple as that. Get a new Sears Diehard Platinum.

[v10enomous]

I went out and did about 85 miles so the controller could relearn the idle and it seems to be OK now. I may just replace the battery and clean the IAC anyway.

[Indy]

Cleaning the IAC (and throttle bodies while you're at it) is always a good idea, just to get rid of build-up. It's an easy job.

I went out and did about 85 miles so the controller could relearn the idle

Good excuse to drive the snake

[v10enomous]

Cleaning the IAC (and throttle bodies while you're at it) is always a good idea, just to get rid of build-up. It's an easy job.


Good excuse to drive the snake

That and great weather but if I need an excuse I may as well sell it...

[JonB ~ PartsRack]

If its NOT the IAC, or the battery, the only other culprit was occasional in 97 and early 98, is a leaky intake manifold gasket.

That would NOT be intermittent except cold vs hot. My bet is battery. Do Die Hard Gold or Plat.

[gerch85]

My 99 does the samething, i just got a new battery, I am going to try the IAC.

[v10enomous]

These cars warm up real quick but I have noticed that the intermittent high idling starts after about 20 minutes of driving. The battery is 4 1/2 years old but it always on a maintainer when the car is not being driven and it did take a full charge on both my regular battery charger and the maintainer. The car has almost 36k miles on it now of which I have driven just about 10k of that and this is the first sign of any issue.

[Ginja]

My 97 did this, worse with the A/C on, would really drop the revs almost to a stall. Changed the battery and fixed the problem

Because it was always on a tender I never noticed the battery was going bad.

[Thawk97]

A former member of the club once mentioned to me that grounding of the wiring harness in various places wasn't all that great which impacted idling for him as his car aged. He said he would get an intermittent high idle and eventually figured it out after going around tightening/cleaning various ground spots to ensure proper ground.

I didn't know him well and had never heard of that issue before, but thought it was interesting.

[v10enomous]

I'm letting the car sit for a few days with no tender on.

[gerch85]

have you resolve the high idle issue? Im still working with mine... its annoying lol