HELP PLZ!!! 89 XJ

Hey guys.. Hopefully I am posting this in the correct section...


I need some help diagnosing my 89 xj with the 4.0 inline 6... I need to get my jeep up and running ASAP for hunting trip, in which I would like to drive my jeep to...I Love my XJ and the jeep community and have had tons of fun in the jeep as it has never let me down until as of the last 9 months or so... I want to drive it!!!!

To the problem... I will try and be as clear in describing the symptoms as I can be... I will also list what i have repaired in order to "FIX" the issue..

Jeep starts up great, just like any other Renux ecu jeep... Problem is after i let it warm up for a good 5-10 mins (that is if it doesnt die at least once). I put it in drive and a take off... When i start to give it throttle the engine starts to lose power and sounds as if the engine is staring itself for air or is caughing becasue its pipes are clogged. Backfires a bit as well..

This happened the first time when i was going up a hill and needed the extra power... pushed on the pedal nothing happened, pushed it down some more, still nothing ... Then the sounds of "caughing" "clogging" backfire... .

What I have replaced:

• Spark plugs
• Plug wires
• Cap/rotor
• Fuel filter
• Throttle Position Sensor

But still the problem exists... Anyone have any ideas??? I have checkd the MAP sensor and that is working properly...I just dont know where to go next... Plus it doesnt help trying to find a decent mechanic who actually knows something on craigslist..... ahhhhhhhhhhhhhh


any light shed would be much appreciated.... :yelclap:

maybe a plugged up catalytic converter? it would cause excessive back pressure from the exhaust and cause the symptoms you are describing. I had a customer with a caddilac that wouldn't go over 45mph, we figured out it was the cat and put a new one on, fixed it right up. Just something to look at. they only last a couple of years usually, if you havent changed it in the last 30k miles or so you may be due for it.

I'll bet a 12 pack it's your crank position sensor.

Good possibility it's the converter clogged. There is a test for that.
CPS is generally a no-start problem, not what you're describing.
Did you properly adjust the replacement TPS? That's absolutely necessary no matter what else you do.

cruiser54 said:

Good possibility it's the converter clogged. There is a test for that.
CPS is generally a no-start problem, not what you're describing.
Did you properly adjust the replacement TPS? That's absolutely necessary no matter what else you do.

Click to expand...

What do you mean adjust the TPS?

There are two screw that hold it onto the throttle body... I removed those and when i put the new one on i made sure to keep the little metal lever on the sensor itself underneath the other metal lever on the throttle body... So that the two would move together....

I do something wrong?

Im also thinking it could be a vaccum leak issue??

90Pioneer said:

I'll bet a 12 pack it's your crank position sensor.

Click to expand...

crank position sensor?? where is that at?

http://www.greatlakesxj.com/tech/TPS.html

I'd be real surprised if your CPS was bad...if it was it'd likely not start at all or cut out on you while driving, it wouldn't cause a lack of power or bogging.

Just my 2 cents.

ParadiseXJ said:

http://www.greatlakesxj.com/tech/TPS.html

I'd be real surprised if your CPS was bad...if it was it'd likely not start at all or cut out on you while driving, it wouldn't cause a lack of power or bogging.

Just my 2 cents.

Click to expand...

I have had lots of other people tell me that as well... thinking maybe fuel pump/pump sock....

Adjust the friggin TPS!!!!!!!!!

ParadiseXJ said:

http://www.greatlakesxj.com/tech/TPS.html

Click to expand...

...and here's a great handy link so that you can...

cruiser54 said:

Adjust the friggin TPS!!!!!!!!!

Click to expand...

One of the "advantages" to having a RENIX is that you CAN adjust the TPS. From the symptoms you've listed and the things you've replaced, the brand new, unadjusted TPS is a very likely problem.

Don't forget to also test it with an analog meter to make sure that the sensor is working smoothly.

I will adjust the TPS. Still not thinking that it is the extent of my problems. I really believe that it is the Fuel pump/sock screen on the pump... AS it is the original pump...

Adjusting the TPS on a Renix is a MUST. It is also a "freebie", only requires loosening two torx screws, a digital multimeter, two small paper clips, and about 10 minutes of your time if you have 10 thumbs. If you have the normal set of phalanges it takes less time than that.

Will do... Is the Fuel pump located in the tank?

Yup.

i had a crankshaftpositioncensor (cps) cause stumbling. it was because after a motor swap, it was sitting on the headers, grounding out.

if you think it's fuel, check for proper fuel pressure, and if the fuel filter looks older then 3-4 years, replace it. (or just replace it, period.)

Replacing it right now... Go under the car and found it on the side of the tank right behind the rear axle on the passengers side... Got the clamps taken off and the wire disconected... I cant seem to figure out how to get this lock ring thing off.. How DO i pull the pump out??

Here is a pic of what i am dealing with...


THXS guys

I believe you have to the turn the locking ring and the whole pump will come out.

did you adjust your TPS properly?

Why in the hell would he adjust his TPS properly? I don't think enough people "in the know" have suggested it to get his attention. I'm outta here. Unsubscribed.

Replaced the filter... Looked to have some stuff on it but wasnt too bad... I cant figure out how the STUPID lock ring goes back on..... AHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH

any suggestions?