Low Idle Problem.

[happyjack87]

I have done some searching on here and found some stuff that might help me I just want to clear something up. I have been for the past 5 months watching my rpm when sitting at lights. While sitting at a light, my x idles at around 450-500rpm, is this normal or is my x not running properly? I have been researching on here, like I said, for an answer and also reading my service manual. If anyone has any ideas what this might be please respond.

Just so those reading know what Im up against: I have checked the IAC valve and cleaned it, checked the resistance across the IAC, took off the PCV valve and shook it, cleaned the throttle body, added some injector fluid into my gas tank, checked the hoses I could see for holes that might be causing vacuum leaks, and some other minor things that I can't remember. Though non of these things helped or proved to be the problem.

Thanks for you help in advance.

 

[RubySlow]

no CEL?
Might be IAC sticking intermittenly, Mine gave me a headache it would idle high then low sometimes a c-e-light some times not.
mine idles around 700-800 ish sometimes mine drops a lil but not as low as yours... Id check for vacuum leaks. re set the computer...

 

[happyjack87]

I haven't seen the O/D light flash and I don't have a code reader so I don't know if its throwing codes or not. Also it seems to run better when its cold and it drops rpms when it warms up, if that means anything to you. Are there any vacuum hoses other than the ones that you can see from the top of the engine compartment? Also maybe Im not looking at the mechanical parts correctly (ie. IAC valve, PCV valve, etc.), could you possibly explain what I should be looking for in these parts, the manual explains it some but not always well enough for the inexperienced mechanic.

 

[Rottie]

"Are there any vacuum hoses other than the ones that you can see from the top of the engine compartment? "

If you have the 4.0 SOHC, then there are 2 large hoses that can be found under the battery. One of them runs under the front of the engine where there is a quick disconnect to a plastic tube. From there it runs up the front of the engine, behind the water pump and pulleys, and I believe it attaches to the front of the IAC. I'm not sure where the other one goes, but you might try to trace it back and look for holes in either one. There are also a few points near the firewall behind the engine where vacuum leaks can occur.

 

[manaen]

"Are there any vacuum hoses other than the ones that you can see from the top of the engine compartment? "

If you have the 4.0 SOHC, then there are 2 large hoses that can be found under the battery. One of them runs under the front of the engine where there is a quick disconnect to a plastic tube. From there it runs up the front of the engine, behind the water pump and pulleys, and I believe it attaches to the front of the IAC. I'm not sure where the other one goes, but you might try to trace it back and look for holes in either one. There are also a few points near the firewall behind the engine where vacuum leaks can occur.

The SOHC PCV is also under the upper intake, the only way to get to it and check it is to remove the upper intake. Since you said you already checked the PCV valve I will assume that you have an OHV motor.

 

[happyjack87]

No I do have an SOHC. and I got to the PCV valve from the top. it was just behind the intake, between it and the firewall. I should have mentioned which engine I had I guess: 4.0L V6 SOHC.

 

[taxman1]

Somewhat off topic, but where exactly is the PCV valve on the 4.0 SOHC? I have looked high and low for this thing and cannot find it.

Thanks

 

[manaen]

Somewhat off topic, but where exactly is the PCV valve on the 4.0 SOHC? I have looked high and low for this thing and cannot find it.

Thanks

between the intak and the firewall.

 

[manaen]

No I do have an SOHC. and I got to the PCV valve from the top. it was just behind the intake, between it and the firewall. I should have mentioned which engine I had I guess: 4.0L V6 SOHC.

If memory serves me right there are some additional vacum lines running under the intake for the PCV system. I guess I need to go look at my motor again

 

[happyjack87]

That was were mine was. There was another thread that I found that had a picture of it, I think I searched for PCV valve and that was one of the things that popped up.

 

[happyjack87]

this may be way out in left field but ill ask it anyway. could this problem be related to the tps? sometimes after the light turns green its kind of like it studders a little. hopefully if this is not something that sounds like it could be the issue someone will have a similar suggestion of something that i can test.

also what is the best way to check for vacuum leaks?