cmuman

1996 xj 4.0 4x4
Here's the symptoms.
Car starts hard after sitting but then will start right up. (cold and snowy here)
Idles at 1500 and then trickles down to 1000
When Driving the trans shifts at 4500 rpm

Manual shifting does nothing
All three throttle body sensors have been replaced in the last few months
Fuel pressure checks out at 30 to 32 psi at idle.
Adjusted kickdown cable
Engine has good spark.
New battery engine cranks good.

I tried to list everything I've done. Any ideas? Is it tcm time? Did my tps go bad? Do I have water in my gas?

I've had a similar problem in the past (hard starting and rough acceleration) and dry gas seemed to fix most of it.

This problem started again after gettin stuck trying to get out of my driveway.

MallCrawlXJ

sounds like a bad tps to me.

i have also had these symtoms when my alt was charging too much.

cmuman

So I threw on an old junk yard tps, and it shifts right. Woohoo!! Now it just lopes in idle about 100 rpm. sitting in park it will bounce from 800 to 900 rmp. Is this ok or should I be looking for something.

tjwalker

When you replaced the throttle body sensors, where did you get them? There has been a rash of complete junk e-bay chinese sensors being sold. They are absolute crap. And also a salvage yard sensor is not verified. And if the TPS that you replaced didn't hold up, the idle air control might not either. So that is in play.

Also need to perform a complete thorough cleaning of your THROTTLE BODY. It is important as they get carboned up over time and miles.

Good luck!

cmuman

Got the tps and IAC from my brother in law who works at advance auto. Throttle body is near spotless. Clean it whenever I have it off.

What is the proper way to test the IAC again?

red97cherokeewithsunroof

When you replace IAC brand new to the XJ (from being in the box) it has to self adjust to the same size as the old one. drive it around for awhile itll get there. normal idle is 1100 rpm. i did IAC and it worried me for awhile.

krash83

I let the xj sit over night in the cold. It started right up. I backed up and it stalled on me. Drove around the corner to my inlaws wasn't shifting again. Drove a little more and after a mile it stalled again, but starts right up. I'm still puzzled.

cmuman

oops my buddy was logged in on my computer. That was actually me posting detail.

cmuman

So I'm going to try a new tsp today to see if my new one and junk yard one have crapped out

MallCrawlXJ

you could have a prob in your harness or connector. does the tps connector look all good?

cmuman

so the saga continues. I got a new tps.... and they gave me the wrong one. 1996 must be the tweener year where they put some old and some new parts on . Since I had the tps off I decided to plug the two in and see what happens. On the older one I have, the jeep would start right up but idle at 1200. When I put the newer one I got last fall in, it wouldn't really start at all. Both caused high shift points. I think both are bad, but the older one is less bad. I'm going to go back to the parts store in the next couple days and get the newer style tps. It wouldn't be too bad if I didn't live 30 minutes from the nearest parts store.

cmuman

Got the new tps. It seems to have fixed the issue. Luckily the one I got last one I bought was still under warranty. So the fix was free. I like how it all ended up.

cmuman

btw the harness looked good

sv41878

Any further issues, Check your 02 sensor with a volt meter. Unplug the sensor, connect positive side of probe to sensor side of plug. Ground negative side of tester. 02 Sensor should produce a fluctuating reading of between 100 and 1000 millivolts. If the reading doesn't fluctuate, 02 sensor is bad. 02 sensor and tps are intimately related, since you changed the tps and it seemed to help a little, I would at least check the 02 sensor.

cmuman

Which o2 sensor should I check? Is one more important than the other.