in park it will rev to whatever you want, but in D it only does 2500 and thats hwy driving doing 70 plus, but in city it is 1500-2000 no more.

 

Had MAF cleaned month ago btw.

 

You should be able to hit the engine tachometer red line in each gear.

 

alright, so do I put it in sport?

 

No, use the left side of the J gate shifter to select the gears manually.

 

Imma do this tomorrow, need some fuel so I should do this on the hwy and do a hard acceleration.

 

1. no DTC's set or pending
2. rough running when cold
3. revs OK in P but not under load in D

Restricted fuel pressure is looking increasingly likely.

Graham

 

I have not changed the Fuel Filter on this car yet. Do you think this could be the cause?

 

You should not be able to rev over 3000 in neutral or park, I'm beginning suspect a ECU problem.

 

Than you RJ, I was trying to point that out a few posts ago. These engines should not rev in Park and his is which is the biggest clue.

 

the N/A XJ8's don't have a rev limiter. I can rev to 3000RPM but in drive it doesnt go above 2500. Thats what I am trying to say, it doesnt sputter or cough it just changes gear if you get close to 2500 rpm. Tomorrow I should try the Manual J-Gate selector.
(couple days ago at walmart I started the car and it had Restricted Performance and CEL - misfire #7 - I revved it and wouldnt go above 3000rpm it would just shake the car. a rough idle.)

 

Fix that fault. Until you do it's putting unburned fuel/air into the cat and causing damage.

 

May be a stretch but when's the last time the cars had the fuel filter changed?

 

never been changed

 

If the filter were the problem it wouldn't accelerate, would probably backfire due to starvation. But the filter probably does need changing.

 

ok, i should replace the filter.