XJ running badly.

[East-Gippsland-XJCherokee]

Originally Posted by rustynuts

I don't think it is a cat or O2 problem.
Only around 3000RPM?
I would suspect ignition.
Can you reproduce the miss while revving in neutral? If so, I would put a timing light over all the leads and look for the miss. I would also read all the spark plugs.

It also does it around 4000rpm, and it only does it under load, I have reved the ass out of it a few times in park and neutral, and it runs and revs just fine. Part of the list of replacement parts are new copper core spark plugs, as I agree when it comes to a miss under load it points to ignition problems, but it does tend to lessen when it warms up. I hae not pulled any plugs as yet as they are about 12 months old, although that means nothing, but will replace them when the new ones come in the mail, yeah living in the country is bloody great, but have to rely on ordering parts via the net, as most times the shops in town don't stock it, and when they do they want top dollar for it! Bugger that.

[East-Gippsland-XJCherokee]

Originally Posted by awg

I couldnt help myself and googled Moe, and sure enough it is in Gippsland, psml

Moe is some way from me, I am in East Gippsland, way less sheep/people around

[East-Gippsland-XJCherokee]

Originally Posted by East-Gippsland-XJCherokee

It also does it around 4000rpm, and it only does it under load, I have reved the ass out of it a few times in park and neutral, and it runs and revs just fine. Part of the list of replacement parts are new copper core spark plugs, as I agree when it comes to a miss under load it points to ignition problems, but it does tend to lessen when it warms up. I hae not pulled any plugs as yet as they are about 12 months old, although that means nothing, but will replace them when the new ones come in the mail, yeah living in the country is bloody great, but have to rely on ordering parts via the net, as most times the shops in town don't stock it, and when they do they want top dollar for it! Bugger that.

I forgot, a new coil is coming as well, just incase as I have had coils go funny on me with other cars.

[East-Gippsland-XJCherokee]

I fitted the cat and rear exhaust back, and the star picket mod does work, the XJ seems to be crispier, shifts somewhat better, and now sound better than a muffled vacuum cleaner. Took it for a spin, and yeah it missed around 2500 all the way up to 4000rmp, warmed up and as much as it still has a slight miss around the 4000rpm range, the warming up reduces the missing by 80%, and if my XJ would not get worse or leave me stranded in the bush I could live with it, but damn I want the miss to be fixed. I came home and fitted the new coil that came in the mail, and it made no difference, miss is still there.

I still have new plugs coming, new upstream O2 sensor new map sensor switch and TPS. I have a new fuel filter ready to go, but will change that out tomorrow as my back is killing me.

My take on this at this stage? When it is stone cold and warming up it misses and stutters really bad, but is way way better when at full working temperature, I sort of think it could still be the O2 sensor seeing that that sensor gets warm when driving, and the same goes for a spark plug. The only sort of feedback I got from an US forum was, check fuel pump pressure, and I just can't see how that would make a difference when cold than gets better when warmed up. New map sensor switch and TPS could be the fix, but I am doubtful.

My next step is a new fuel filter, I will strip down to my birthday suit and run down the street if that's the culprit, so if you spot a naked bloke down the road you know I fixed my XJ LOL.

Stay tuned and thanks for your help, and please keep the feedback and suggestions coming, and I will update step by step.

[LuluBelle]

Originally Posted by East-Gippsland-XJCherokee

the new ones come in the mail, yeah living in the country is bloody great, but have to rely on ordering parts via the net, as most times the shops in town don't stock it, and when they do they want top dollar for it! Bugger that.

YOU GOT SHOPS!!...............everything on my XJ was purchased online
I Know the Feeling!
Hope the new gear sorts it for you
In the middle of no where a broken XJ in the yard and sweating on the Australia Post Parcel delivery Lady (Subcontractor)................................... ....................For Needed Parts Gotta love the country ............But would never move back to the City

[awg]

Originally Posted by East-Gippsland-XJCherokee

It also does it around 4000rpm, and it only does it under load, I have reved the ass out of it a few times in park and neutral, and it runs and revs just fine.

If it ONLY misses under load, but will free rev otherwise, I was taught (on tricky to tune multi-carb cars) that points towards a fuel/air issue

vehicles controlled by multi-electronic sensors are not my forte, even though I am qualified in Electronics, but I know dud sensors can cause weird problems.

have u double checked the integrity of all vacuum hoses?

[LuluBelle]

Good point that's something we all overlooked!