2 Questions: Idle Behavior and Oil Pressure

[fendermb4]

Question 1:

When my truck is in park, it idles at around 1500rpm. If I put it in gear, its more like 1000 rpm. It seems unusually loud at idle, so I'm thinking 1500 rpm is too high. Is this likely to be TPS or IAC?

 

Question 2:

I recently put in a full gauge cluster and swapped out necessary sensors. Everything works, except my oil pressure gauge isn't how I expected it, and I'm wondering if this is normal behavior. When I start the truck, it climbs to around 18psi. While driving it doesn't go any higher than maybe 22psi. If I floor it while I'm driving, the needle really doesn't move much, nor does it fall too far at idle. It isn't low on oil, nor is it leaking any. Could this be an actual oil pressure problem? Is it more likely that I have the wrong sender in there?

 

By contrast, my 99 XJ sits at 40psi and the needle moves a fair amount if I go from idle to floored.

 

Thanks for your help!

 

For posterity, this ended up being the wrong sending unit. When I checked the pressure with a mechanical gauge, it was fine.

[Pete M]

Did the idle start doing that out of the blue? I think the idle should be at 750 so if it's high all the time I'd look for a vacuum leak first.

[87manche]

check your TPS or for a vacuum leak.

Mine idles at 6-700 rpm.

 

the oil pressure guage sounds like the wrong sender. I'd verify the oil pressure with a mechanical guage, just to make sure your 4.0 doesn't have horrible pressure, then troubleshoot the cluster guage.

[fendermb4]

check your TPS or for a vacuum leak.

Mine idles at 6-700 rpm.

 

the oil pressure guage sounds like the wrong sender. I'd verify the oil pressure with a mechanical guage, just to make sure your 4.0 doesn't have horrible pressure, then troubleshoot the cluster guage.

 

There isn't a vacuum line to the TPS is there?

 

The idling thing started after I did the following all at once:

-Removed TB, cleaned it out. There was a lot of gunk in there.

-Changed airbox. Replaced PCV line to airbox with a breather on the valve cover.

-EGR vacuum lines were disintegrated. Replaced all the EGR lines with new vacuum hose.

-Plugged several existing vacuum leaks.

 

As near as I can tell, there aren't any vacuum leaks now. I was wondering if when I was cleaning out my TB maybe some gunk got into the TPS or IAC, but I wanted to know if that symptom was typical of either of those sensors failing.

[JeepcoMJ]

There isn't a vacuum line to the TPS is there?

 

The idling thing started after I did the following all at once:

-Removed TB, cleaned it out. There was a lot of gunk in there.

-Changed airbox. Replaced PCV line to airbox with a breather on the valve cover.

-EGR vacuum lines were disintegrated. Replaced all the EGR lines with new vacuum hose.

-Plugged several existing vacuum leaks.

 

As near as I can tell, there aren't any vacuum leaks now. I was wondering if when I was cleaning out my TB maybe some gunk got into the TPS or IAC, but I wanted to know if that symptom was typical of either of those sensors failing.

 

did you cross over the vacuum lines ot the egr?

 

then, with the oil pressure gauge, 22psi isn't bad at IDLE but is really bad at speeds. check sending unit for correctness, check pressure mechanically, check the gauge. if it's the correct sender, and your engine doesn't clank or anything, make SURE you do a mechanical pressure test. if that's correct, you have a faulty sender or gauge. there's really not much for wiring between the gauge and sender, so it is not that.