Intermitant Shifting/Idle Problems

[rtjones]

I have an intermitant problem with my 2000 Sportage. Every so often it decides that the automatic transmission is going to shift at odd rpms (sometimes way too high, other times way too low) this is also accompanied by a high engine idle (2,500-3,000 rpm). This will bring on the check engine light but the dianositc codes offer little information - Kia dealer told me it could be a bad thottle position sensor or a bad mass airflow sensor, Autozone told it was a misfire on cylinder 3. It is definitley not a misfire and could be's do not sound very definite.

Any help?

[Axe Man]

Yep, can help.

First, it sounds like your dealer is not very competent because this is a common problem on Sportages.


Your dealer is "half right" when he says it could be the throttle position sensor or the mass airflow sensor. And include the IAC (Idle Air Control) valve in that too. The issue is not the sensors themselves. It is the electrical connectors TO the sensors. They develop corrosion and high resistance over time. The result is random CEL's (check engine lights) and the most common symptom where the engine idle suddenly and without warning jumps up to 1500 RPM or above.

The fix: There are two fixes. Fix 1: Unplug the connectors and clean them up as best you can and re-crimp them. You should be good to go...at least for a while. The problem will eventually come back. Fix 2: Unplug the electrical connectors and cut them off. Solder the wires directly to the TPS, IAC, and MAF. Yes, this is a drastic move and your dealer won't do it. But guess what? It fixes the problem PERMANENTLY. I've done this on my Sportage and haven't had any wacko idle problems since.


Also, one other item to check. Make sure the ground wire between the battery tray and the intake manifold is corrosion free and tightly connected.

[rtjones]

I knew the connection on the MAF was not great, I'll check the other too. Thanks for the help. I really didn't belive the sensor and it sounded like a connection problem - but my pessimistic view was whatever was most expensive. This sounds pretty easy, I know where the MAF is I'll need to poke around a bit to find the other two but I have a good clue where to look.

Rich

Originally posted by Axe Man@Sep 9 2004, 06:42 AM
Yep, can help.

First, it sounds like your dealer is not very competent because this is a common problem on Sportages.
Your dealer is "half right" when he says it could be the throttle position sensor or the mass airflow sensor. And include the IAC (Idle Air Control) valve in that too. The issue is not the sensors themselves. It is the electrical connectors TO the sensors. They develop corrosion and high resistance over time. The result is random CEL's (check engine lights) and the most common symptom where the engine idle suddenly and without warning jumps up to 1500 RPM or above.

The fix: There are two fixes. Fix 1: Unplug the connectors and clean them up as best you can and re-crimp them. You should be good to go...at least for a while. The problem will eventually come back. Fix 2: Unplug the electrical connectors and cut them off. Solder the wires directly to the TPS, IAC, and MAF. Yes, this is a drastic move and your dealer won't do it. But guess what? It fixes the problem PERMANENTLY. I've done this on my Sportage and haven't had any wacko idle problems since.
Also, one other item to check. Make sure the ground wire between the battery tray and the intake manifold is corrosion free and tightly connected.

Quoted post

[Axe Man]

The IAC is the unit on the aluminum intake pipe roughly above the exhaust side of the engine. It has an electrical connector that faces straight up.

The TPS is located right on the throttle body where that same intake pipe bolts to the throttle body.

[rtjones]

Thanks - I had popped the hood this morning, and that was what I thought, your confirmation makes me feel better. The connections on the TPS and IAC look pretty tight. The insulation is broken on the MAF so I will concentrate on those wires first. If the others "look" good should I leave them alone (ie don't fix what ain't broke) or is it a pretty chance I am having a problem with one of those also?

Rich

Originally posted by Axe Man@Sep 10 2004, 05:59 AM
The IAC is the unit on the aluminum intake pipe roughly above the exhaust side of the engine. It has an electrical connector that faces straight up.

The TPS is located right on the throttle body where that same intake pipe bolts to the throttle body.

Quoted post

[Axe Man]

Even though the connectors look tight doesn't mean anything. The electrical connector can still develop high contact resistance even if tight.

Try this: With the engine idling wiggle the connector to the IAC. I'll bet the idle speed will change or the engine might even stumble. If it does that connector needs to be pulled off and at least have the contacts cleaned.

[k5mommy]

This is about the same problem we are having with out 02 Sedona. It started a few months ago. Once I shut the engine off and start back up it works fine but the engine light stay on. It does it every once in a while, not constantly.

[k5mommy]

Hubby called and talked to a tech. He said it sounded like a speed sensor. Guess we'll see