smelser509

picked up a 93 sport 2wd last nite the guy said he went to the store it was fine started it up to come home and it started loosing power and he had to press the gas to keep it running and still it would die sometimes
So i go look at it i get there engine is cold i turn the key it cranks a few time and starts idles fine for about 1 or 2 min then starts trying to die as soon as i pressed the gas it died!!! I didnt try to start it again i just paid them for it $500 and my friend is picking it up and bringing it to me tomorrow....... SO WHERE DO I START LOOKING FOR THE PROBLEM??????? HAS 180K ON IT THANKS

Destination XJ

Any smoke? How did the oil look?

Maybe he patched a gas line with neoprene and the line is collapsing.

Maybe It could be a lot of things. Need more info.

BlackXJ

The very first thing your going to want to do is make sure it has fuel pressure. Get a Fuel pressure guage and screw it in to the shreader valve on the fuel rail and it should be around 49psi. If you are too cheap to rent a guage just hold the valve in with your finger and have someoen turn the key. should squirt pretty far / strong.. If you have a low reading that means your problem is probably in the fuel tank/fuel filter.

If you have good pressure, then your going to start looking at sensors on the throttle body. Right now Im thinking to myself "Its the IAC motor", but lets elaborate a little bit first.

Check for Vaccum leaks also. An easy way of doing this is getting a can of starting fluid and spraying all the lines and if you hear a change in RPM than you know you have found it. I highly doubt this is your issue, but its also worth checking for 4 bucks of starting fluid!

Does it overheat? Make sure if it full of coolant. Run it with the radiator cap off and make sure it stays full.

Take the throttle body off from the manifold (removed by 4 bolts. Unplug sensors. If your new to the 4.0, mark each sensor 1-4 with some painters tape and then mark the connetor as well for each one.

-Take off the IAC motor (closest to the valve cover) very carefully. Is it covered with carbon? If so you can try getting some brake cleaner and cleaning it. This MAY help, but in some cases (like mine, it looked brand new) the IAC can be totalled all together and not even look it.

Take off the TPS (throttle position sensor). This is the sensor closest to the firewall. Make sure its clean and theres no dirt (although, I highly doubt this is it). There are ways you can check the TPS with a digitial multi-meter that a quick search through the forum would reveal.

The first thing I would replace is the IAC motor. It has a lot to do with the IDLE and it can and will and has caused the same issue you are describing. Mine idled "okay" but when i gave it a quick hit of throttle it would cut out and want to die. If I SLOWLY eased in the throttle, it ran alright. Go buy the IAC at advanced auto.. if it doesnt work, make sure its clean and un damaged and tell them it doesnt fit and your jeep has a 4 cylinder.

Hope this helps... good luck with your cherokee!

BlackXJ

As I re-read your original post, thats actually the same problem I had! Ran good for a few minutes enough to move it in the driveway un-noticably, then when I went to drive it, it would cut out and I had to slowly ease in to the throttle to drive it.

Mine was a combination of two things. There was very little anti-freeze in the system, and The IAC motor. i would first make sure your anti-freeze is full (without it, the computer with get thrown "out of loop" and not run correctly) and then if that checks out, replace the IAC motor if cleaning it does not work. Its about 80 bucks..but will get ya running!

smelser509

ok got the jeep to the house it starts right up and runs great til it starts to warm up then it starts trying to die stumles badly then will smooth out and idle up to 2000 rpms then start stumbling again and it will take throttle slowly but if you give it quick throttle it wont take it and pops thru the intake ... where do i start.......

BlackXJ

Pm sent. That is a symtom of a failed IAC motor. 80 bucks and your back on the road. I already posted about 3 paragraphs about it.

smelser509

needs a tune up to so im gonna do that to what plugs do you recomend ?

Bustedback

Check for a clogged exhaust. Put a vacuum gauge on the intake manifold and it should read between 15-20hg at idle, if the exhaust has a restriction or clog, the gauge will start to read pressure instead of vacuum.