Diplomat1

Looking for some advice on my 02 grand Cherokee laredo 4.0. If anyone read my Other thread I got the car with a couple of problems I ended up changing the ecu, crank and cam sensor new coil and plugs. Now I'm having a overheating and high idle problem and don't know if they are related. The car runs smooth but when I start the car cold It idles at 1500 rpms. As the car warms up the rpms slowly rises. After about 4-5 mins of running it stays at 2k rpms without me touching the gas pedal. Just to see what happens I tap the gas pedal and it then settles at 3k rpms. If I restart the car it will idle at 2k rpms. I used my scanner and the tps is at 11.4% at closed throttle. I also noticed the oil pressure gauge on the dash stays at high but I believe that is a bad sensor. Now for the overheating issue. Since the car is running with a high idle the coolant temperature gets to around 219 degrees. The weird part is When I shut the car off the coolant temp goes up and gets to around 250 degrees. Why is that? I don't know what to do next looking for some serious help. I am thinking I should start with a new thermostat and water pump. As for the high idle could it be a bad Iacv? Vacuum leak? Is there a way I can check the iacv? Here is a video of it running. Thanks in advance guys

https://youtu.be/BNatckWPETQ

Willys55

could be a faulty idle air control valve, could also be caused by a vacuum leak on the intake manifold, which with the 4.0L is not uncommon...so look there first. as far as the temp, with the engine off and the coolant not moving the temp will rise , which is normal....as far as 219 degrees, most of these engines run between 205 and 220 all day long

Diplomat1

That's what I keep hearing weird thing is this wasn't doin it before I put the mopar crank sensor in. The sensor fixed the p0351 code and now runs smoothly on 6 but the high idle issue came after the sensor was installed. So I have to maybe relearn the crank sensor? Could I have installed it incorrectly causing a high idle? I followed the instructions. Thanks for the responses

Diplomat1

Just went back and got some more info. On initial start up the car idled around 1100 like it normally should then in about 2 mins it starts rising like it did before. I also got a new code p0500. Is that causing my rpm problems? What should my next step be?

Diplomat1

I I took the throttle body off took sensors out and cleaned it. I put in a new aftermarket tps and iacv in and installed and it ran way better. Took it for a drive and the idle numbers were great in every gear. I came back stopped the car and came back 20 mins later started the car and again the idle started creeping up. Now I don't know if its Warm issue or what cause it ran good when at operating temp. I then got another new tps and still
Same thing. I am gonna pick up a throttle body from a junkyard and hope they got all the sensors on them. I left the truck with both cables off the battery hoping for a reset of the ecm. While looking for the vss I found my neutral safety switch wiring frayed so I am gonna replace the connector and see what happens. I also plan on dropping the tranny pan and changing the filter and fill to correct level. When I pulled the dipstick it seemed overfilled and also gonna change the vehicle speed sensor. Here's a pic of the frayed wiring.

https://ibb.co/h7wcoF

freegdr

Sounds like a tps issue.

dave1123

Check the seal on the MAP sensor. If that's leaking vacuum, it can cause the PCM to do weird things.

Diplomat1

Gonna put on a new throttle body hopefully that has a good working tps and map vacuum line is not leaking