I have a 2004 jaguar s type and this seems to be a constant issue with alot of people and cant find any info relating to me so im posting this but it doesnt go into restriction mode until i start driving and then it only does it after a little bit like if i pull out of my sub and hammer on it it just goes into performance restriction mode and stutters and wont go above 3k rpm but yet if i had low fuel itll do it perfect no stutter no nothing doesnt really make any sense to me my cats were clogged up so i emptied em out completely that might the the reason so im gonna try the spark plug anti fouler trick and see if that does anything but it seems like everything ive tried doesnt work i even have two batteries running my car because i thought maybe that was the reason.

 

Welcome to the forum zach4577,
Please post an intro in the new members section when you get a chance.
Have you checked the codes stored in the car when it goes into RP, if not please do so and post the results so members can try to help.

 

I'm wondering if that's the longest sentence ever on this site?

BTW don't rev so high except when driving or you risk damage.

 

First i dont see why your worried about the sentence and second i clearly stated that it was when i was driving it did it. and i had the codes ran and they told me it was my cats but i dont see that could be the only problem they were very vague about it.

 

buy yourself an elm 327 and read the codes using a free program. Also download a copy of the JTIS from the stickies. Once you have the codes tell us and we will see if we can help you.

 

Perhaps the sentence length made the second point not so clear?
Anyway, please post the actual codes.

 

Vacuum leaks can cause restricted performance. The ELM 27 will show you fuel trims, and you can do various tests at idle, at load to see of it points toward vacuum leak. (See smoke tust idea below to id vacuum leaks). Leak at downpipe exhaust flange right before O2 sensor can also cause lean condition and restricted performance. That was my problem. Took a while to figure out. And you can do simple propane in air intake and see if fuel trims drop (if ELM 27 won't read oxygen sensors directly) to test oxygen sensors.

Fuel trims are key to many diagnoses. Get ELM27 and watch this and you can become a pretty decent amateur mechanic.

https://youtu.be/5WnM_NsOtd8

Cigar smoke test.
See nit wit Scotty Kilmer's youtube on cigar smoke machine. It actually works.