Raul Ruz

Hi Guys, im new to the forum.

So i have own my 98 2 door 2,5l 2wd XJ for over a year know and obviously a lot of money has been invested on her. The jeep is my daily driver an has a little over 200,000 miles, the truck is in very good condition and 0 rust issues cus here in northern Mexico is just ... dry. So, the thing is that the other day i removed the throttle body and gave it a quick dry clean without removing the sensors. When i put everything back together to my surprise the jeep did not start, it just cranked on and on. I double checked the sensor connectors ( including other ones like CPS, ppm, grounds etc. ) and they are fine and firm on the sensors.

I bought a new Map since all the sensors are the original ones (just installed it but still crank no start) and also bought a new tps but that one arrives tomorrow. The jeep has new injectors, spark plugs, rotor, cap, cables, 1 year old battery, FPR and other stuff. Also, all fuses seem to be alright. This Xj is an SE model so is very basic and was running fine before removing the throttle body or disconnecting anything.

Any ideas? This jeep is my baby and also my daily so i need her love to move around.

lawsoncl

What's a dry clean? Try unplugging the TPS and see if it starts.

Raul Ruz

Thanks for the quick reply man! What i meant with the dry clean thing was that i did it with just a tissue and no liquids. Ive just tried starting it with the tps unplugged and well ... no success, just the check engine light . Meanwhile im gonna try again tomorrow with the new oem tps installed ( i think there's no calibration needed )

dave1123

Make sure there's no particles of tissue in the MAP sensor port. Also, use electrical cleaner in the electrical connectors and fill them with dielectric grease. If your MAP sensor is mounted remotely, make sure the hose isn't damaged. Also tissue in the idle air port. If the plunger gets stuck, it'll bleed too much air to start, or if it does, the idle will be high.

Raul Ruz

There are no particles or pieces left on the sensors, actually i didn't even touched the iac while cleaning the tb cus i know is delicate.

Tried again today with the new tps, again no success. I don't know what is going on, also tried starting the jeep with the iac disconnected and it didn't start, just check light. Maybe i should try with a new CPS but i can't find it online here in Mx. Neither the iac for this 98 2.5. There is a mopar service center not too far away, idk if they can get those parts for me.

Im thinking about a new pcm but finding one compatible with the 2.5 rwd 98 setting is gonna be impossible

lawsoncl

Do you have spark when you crank?

awg

after checking for spark

I would suggest testing the relevant sensor voltages with a backprobe and multimeter, using the FSM as a guide

It may be that flexing the wires has cracked one inside when moving the TB aside

they can get very brittle with age & heat

Raul Ruz

Nope, i have no spark. I called mopar and there are no shippings for like a month. I have checked the cables visually but nothing more, i will use the multimeter ... that actually could be the cause

shelby987

I know you have said that you have no spark, but try to spray some starting fluid down the TB and see if it starts.
I had an MJ with a similar issue, tracked it down to a CPS, signal drops out, ecu kills spark and you chase your trail.
There is a good link to checking voltage at the cps I will see if I can dig it up.

Dave51

Check all the fuses and relays.

Raul Ruz

I´ve checked fuses and relays and installed a brand new mopar CPS. Still no start ... im gonna try and get a multimeter since i do not own one for now.

Also i have double checked the wires on the sensors and they look fine, not cracked or something, still soft and flexible

Raul Ruz

Is curious cus i doubt the computer is responsible for this. I get the 3 sec engine light bus, also i get the pump working before i crank the engine. The fuel rail has pressure, all grounds look okay, zero rust. Fusebox okay, nothing blown and i have interchanged the four relays since they are the same part.

The jeep acts normal in every way. As i said, she was running perfectly before i messed up with the tb. I don't think the coil is bad, maybe the cam sensor on the distributor.

Dave51

Yeah get that and we'll check both the CPS and the CkPS, it's easy enough.

Dave51

I have to check the manual on that tho to make sure it's the same as a 4.0, or perhaps someone who knows will post.

Raul Ruz

Well, here we go ... after replacing MAP, TPS, Crank sensor, Cam sensor and the coil with no success ... the responsable for the no start was the PCM. I had the 3 sec bus on the check engine light and everything was normal. But it seems that the computer wasn't sending ground to the system. Something while i was working on the truck must have damaged it.

So ... guys, if you plan to mess around with the engine, even the most basic stuff i would recommend to always disconnect the battery and let the system drain a few minutes to prevent random things like this.

After PCM replacement the jeep is now running great and with all the new parts oem except the cam sensor (went for standard brand since mopar has discontinued the part) she feels like a new truck (powertrain at least lol).

Thank you all for your comments and support hehe