Tps or IAC or ???

[Ecomike]

Mine is not a Renix would it still all be the same.

What "it" are you asking about?

Ehall confirmed that the fuel pressure is 39/31 just like Renix.

 

[2jeepdrivers]

Sorry for being so vague, I was referring to the vacuum diagram. It looks like my cherokee is going to the back burner anyways my fiancee's liberty just broke down so I am working on it to and I just got my tranny back for my CJ6. Thanks for the input guys I will post what it was when I get back to it.

 

[2jeepdrivers]

Bringing my old post back to the top instead of starting a new one. Just got back to working on the Jeep, I have replaced the IAC, TPS, checked all of my vacuum lines replaced my Fuel Pressure Regulator and it hasn't changed a thing. The jeep will start on a regular basis now, but it almost sounds like an old carbureted vehicle that will sometimes "diesel" when you shut them off. I can feather the gas and finally get the rpms up and when I do it as smooth as can be. but if I let it go back to idle it idles around 300rpm and like I said sounds like crap. If I let it set and run for a minute it will run up to about 1000rpm and smooth out for a minute but then it drops right back down. And I went to the salvage yard to look at the map connections on some of them and on all of the HO 4.0 it went straight back to the intake not to the throttle body so that is not the culprit. I am stumped and the way it is going I am going to have my Scout completely rebuilt before the XJ see's another trail unless somebody has an idea that I haven't tried yet.

 

[Ecomike]

Bringing my old post back to the top instead of starting a new one. Just got back to working on the Jeep, I have replaced the IAC, TPS, checked all of my vacuum lines replaced my Fuel Pressure Regulator and it hasn't changed a thing. The jeep will start on a regular basis now, but it almost sounds like an old carbureted vehicle that will sometimes "diesel" when you shut them off. I can feather the gas and finally get the rpms up and when I do it as smooth as can be. but if I let it go back to idle it idles around 300rpm and like I said sounds like crap. If I let it set and run for a minute it will run up to about 1000rpm and smooth out for a minute but then it drops right back down. And I went to the salvage yard to look at the map connections on some of them and on all of the HO 4.0 it went straight back to the intake not to the throttle body so that is not the culprit. I am stumped and the way it is going I am going to have my Scout completely rebuilt before the XJ see's another trail unless somebody has an idea that I haven't tried yet.

I have not reread the old posts here, but your latest description sounds like a problem I had when I plugged one or two of the new sensors into the harness connectors backwards. It was the TPS and O2 sensor. IIRC the Idle cyled up and down because I had the new TPS connector (ECU three pin flat side, not the TCU four pin square side) plugged in backwards. The harness clip was broken off so it was possible to install the connector backwards, so I had A-C and C-A connected instead of A-A and C-C. The ECU tried to compenstate and the idle ran up and down from 200 rpm to 1000 rpm on about a 5 second cycle.

 

[2jeepdrivers]

Alright I have had a chance to mess with the Heep somemore and here is where I am at. Input voltage and return are good on the TPS, which is new, I also ran an extra ground off of it to see if that might help even though it ohmed good. I have figured out that if I unplug the map sensor and throttle sensor it will idle consistently around 500rpm If I unplug a vacuum line it idles really smooth at about 750rpm and I can get it to rev I even drove it around the yard other than some sputtering it isn't to bad. But as soon as I plug back in the map sensor or the Tps it dies. I checked and I am getting return voltage back to the ecu from the tps and map so I am starting to think it may be a bad ecu, if anyone has any input or thought on this please respond.

 

[Ecomike]

Alright I have had a chance to mess with the Heep somemore and here is where I am at. Input voltage and return are good on the TPS, which is new, I also ran an extra ground off of it to see if that might help even though it ohmed good. I have figured out that if I unplug the map sensor and throttle sensor it will idle consistently around 500rpm If I unplug a vacuum line it idles really smooth at about 750rpm and I can get it to rev I even drove it around the yard other than some sputtering it isn't to bad. But as soon as I plug back in the map sensor or the Tps it dies. I checked and I am getting return voltage back to the ecu from the tps and map so I am starting to think it may be a bad ecu, if anyone has any input or thought on this please respond.

What is, was the return voltage at the ECU at Idle? Was it the same as the return voltage at the TPS and MAP sensor, thus indicating the wires are OK?

Id say your down to wires or the ECU.

 

[2jeepdrivers]

Off of the TPS it didn't drop at all and off of the map sensor it dropped .01 volts which I would say is my cheap multimeter either way it is not enough to make a difference so I am going to try a different ECM off of a buddy of mines XJ.

 

[lhilt89xj]

new here, but had similar problems with my 89 that I finally got on the road. Mine was a leaking EGR solenoid, which was hard as *(&(*&(*&( to narrow down. Actually how I found it was to lean over the driver's side fender looking for vacuum leaks, and my finger got sucked onto the 'plug' which stopps up the unused vaccum outlet on the solenoid. the solenoid had been bad for so long that it had pulled the seal out of the plug.

It ends up presenting like a stuck EGR, which at temperature, will dump your engine. I got by with mine until I got to the junkyard by plugging the Vacuum lines going to and from the solenoid, basically bypassing the EGR. Here's a quick test for you to perform:

Run it at idle, let it warm up until it starts the drop in RPMs, and using a screwdriver, push the EGR valve linkage towards the motor. If the RPMs pickup, then your valve is either "Sticking" or the solenoid that controls it is bad/connector loose.

The egr solenoid is on the driver's side of your engine compartment. If you disconnect the vaccum lines and take the guy off and blow through the inlet (side with just one port) air should only be able to go through one outlet (side with two, but only one used vacuum ports). If, after blowing through, you plug that with your finger and air still escapes through the other hole, your solenoid is leaking, and consistantly keeping the EGR valve partially open simulating a stuck valve.

 

[2jeepdrivers]

H.O.'s do not have an EGR. Thanks for the advice though maybe somebody else will find it helpful in a search. I pretty well have mine narrowed down to the ECU.