2005 XK8, won't accelerate
 

Hey guys
I have a 2005 xk8 with 115k miles and a 4.2 engine that will not accelerate. It will accelerate under load to 2100 RPMs and then start breaking down. You can rev with a no load to 4100 and then starts breaking up. I have replaced plugs,all coils and injectors, fuel pump and fuel filer twice, air filer. Still no change. I have a donor car same year with no issues and have swapped MAF sensor ,TPS along with throttle body, fuel pressure regulator all with no help. Car has 150 lbs of compression on all cylinders and 50 lbs of fuel pressure also i unhooked the converters and drove and still no difference.
If anyone has any ideas i need help !!!!!

Welcome to the forum wolfy27,

I've moved your question from Jaguar Forums Feedback & Suggestion Center to XK8/XKR forum. Members here with the same model will be able to help.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

Get the codes read and post them back here

The car is equipped with a rev limiter in P & N to around 2500/3000RPM however, it does not apply when in D. This tells me the car is in Restricted Performance and you need to find out why. Have the OBDII codes read and post the codes not what they tell you they mean.

Gus
www.jagrepair.com

As others have said, you need to get data. Stop throwing parts at the problem, and let the car tell you what is going on. You can start with a cheap ELM327 off of eBay and TorquePro on Android (or equivalent on iPhone). There are actually a lot of parameters available over OBDII on these cars, including fuel pressure, air flow, fuel trims, etc., in addition to all the trouble codes.

In the meantime, parts store typically let you use a code scanner for free...

Best of luck, keep us posted.