Would this cause high Idle?

Bad Fuel pump, Injector or Fuel Pressure Regulator? I have a new Map,O2,TPS, IAC. TPS is adjusted right. Also put a new connectors on the Jeeps wireing Harness that connects to the TPS. Checked and Cleaned the IAC and TB 16,000 times. No Vac leaks and re-spliced and Fastend my Engine gounds and ground strap. Same probelm....Start the Jeep it will start fine and Idle right. Turn it off and back on and Its shoots to 3,000 and sometimes goes down but most of the time it stays and i have to slam it into R and it goes down but even then it won't go all the way down. Im out of ideas.

Rambopants said:

Bad Fuel pump, Injector or Fuel Pressure Regulator? I have a new Map,O2,TPS, IAC. TPS is adjusted right. Also put a new connectors on the Jeeps wireing Harness that connects to the TPS. Checked and Cleaned the IAC and TB 16,000 times. No Vac leaks and re-spliced and Fastend my Engine gounds and ground strap. Same probelm....Start the Jeep it will start fine and Idle right. Turn it off and back on and Its shoots to 3,000 and sometimes goes down but most of the time it stays and i have to slam it into R and it goes down but even then it won't go all the way down. Im out of ideas.

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Vacuum leaks can be hard to find and hear especially at the lower intake manifold or the vacuum bottle on the front, inside the dash....... But yours sounds like an electrical issue since it comes and goes with just a shut down and restart. Check the TPS idle voltage when it hits 3000 rpm, see if it is off then, and if it is track down why while it is off. Should be about .72 volts at idle. I have had a loose floor mat do that me, hangs up the gas pedel randomly!!!

Also the B+ latch relay needs about 7 second seconds of the ignition switch off to reset the IAC for the next restart. The B+ latch relay or its wiring can cause high idles too as it powers the ECU after shutdown for about 10 seconds to allow the ECU to reset the IAC.

Keep in mind vacuum leaks usually cause a constant high idle, unless the IAC can sometimes correct it, then it can come and go, or the vac leak can come and go witrh metal expansion from heat like an intake manifold leak.

Just keep looking in the same areas, it will eventually reveal itself.

Have you ohm tested the IAT (or MAT as some call it), temperature sensor in the intake manifold? IIRC I had some idle problems and definately had cold start problems when it went out.

Also do you have the CCV vac lines back to OEM and clean and tight on the valve cover.....? Many have customized ther CCV lines to stop oil getting to the air filter and end up creating a a disguized vacuum leak on the renix models. There is a 2.2 mm orifice in the CCV line that needs to be there and be clean to get the right air flow rate from the engine block to the intake to remove bypass gasses. If that is not there it acts like a vacuum leak and can cause high idles.

Where is the B+ Latch Relay? I did unplug the IAC then started the jeep and the Idle was fine. Plugged it up again and its stated f'n up again. Im thinking IAC or its relay if it has one.

Mine was doing the same thing and it turned out to be the IAC. I had cleaned mine two or three times. Change your IAC valve.

I just bought it less than a year ago

What year is it? Do you have any manuals yet? Haynes, Renix FSM....? From your first post I am guesing it is a Renix?

B+ latch relay is IIRC on the passenger side one of 4 relays in a row between the battery and the coolant bottle. One is AC clutch one is fuel relay and the other is ???

rambopants, I was having the same issue on my 89 4.0, Intermittent high idle 3000rpm-just screaming. I replaced the tps first and same thing. I replaced all my grounds including dipstick tube and firewall, and ran an additional heavy cable from the batt to the intake manifold, replaced the Iac motor and the b latch relay. All was good for almost a week, It did it again last night and I noticed the j shaped hose from the ccv to the airbox was collapsed. I don't know if it was related but I replaced it and re set the computer and good to go again.