XJ running badly.
 

My XJ has a miss at 4000rpm. But my XJ is not throwing codes.


It plays up under load whilst driving. Starts really well, idles perfect, and tends to lessen when it warms up. Last week when I went to pick up my new rims, it got really really bad and felt like I lost more than 50% of power, at one stage I could not even rev past 2500rpm and when I put my foot to the floor, it just did not go anywhere past 2500 revs, even back fired a few times.

I thought seeing I live in the country it could have been bad fuel, I got fuel at 1/2 full tank, and filled it with the best fuel I can get being 98ron, and my Jeep seem to drive better, power was back again. But I still have this stutter/miss in second gear when it hits 4000rpm's, but no backfiring of any kind.

Prior to this about 2 weeks ago I had a parasitic draw that was draining my battery flat in less than 2 days, but I found the problem, it was the service light under the hood, so I pulled the fuse and left it out, and that fixed the drain, a few days after that the miss started.

My plugs and leads are about a year old, same for the air and fuel filter, and I also replaced the IAC at that stage. I have ordered new plugs, new fuel filter, new map sensor switch and TPS and a new coil is all coming in the mail this week. I already have the crank sensor switch, and will have a go at changing that out the next day or so (not looking forward to it with a bad back) to see if that fixes the problem.

OK, I changed out the crank sensor switch, and it was not that hard to change. But guess what? My XJ now stutters around 2000rpm, stutters around 3000rpm, and still stutters just past 4000rpm. But where it has gotten really worse whilst driving in Drive, it feels like it is kicking back a gear while I am doing about 80 k's/50 miles. It still starts up the same, idle is the same.

As much as I have other parts coming this week and the next few weeks as well, its really got me stuffed, I was open to the fact replacing the crank sensor switch might not fix it, but why did the whole stuttering thing get worse is beyond me!

Help guys! Anyone?

I readjusted the throttle valve/trans kickdown cable just to insure that was fine, and it made no difference. I went for a drive and it is now as bad as it was last week, it stutters really bad, and bucks for a split second, and jolts the whole car, it is now even affecting the idle as that is not so smooth anymore. I also did the keydance, and no error codes.

It has gone downhill even more, it now burps, stutters in park, not under load, and even stalls now if you don't ride the throttle when reversing or driving at lower revs. It is night time now and cold, but will in the morning change over the crank sensor switch but to the old one that came of my XJ, just to see what that does. Could it be a dying fuel pump? Could it be a coil that is going downhill fast? As it sounds to me like an ignition miss, or fuel problem of some sort.

Oxygen sensor maybe, you can test by just unplugging it. Computer will go into a default setting for fuel/air mixture and should run pretty smooth but quite rich.
It's worth a try at the very least.

Mine is a 1996 model, does it have 1 or 2.

Cheers

Mine was 96 too, I had problems with mine. To be honest I can't remember if there was 2, but it's just sliding under and unplug it. I can kind of remember it being before the cat converter, sorry but it was about 7 years ago.