Ok so I've done all I know and now I really need help. I have a 2000 XJ8 VP. I had a problem with the engine running rough. I put new plugs in, no change, so I put in all new coils, still no change. I had in the passed, moved the throttle position sensor and thought maybe I may have messed it up so I put a new one in. No change. When I accelerate down the road, it runs great. But, when it idles, it's rough and the "restricted performance "" lights up. I can clear that but after a few minutes, it comes back on. When I read the code, it comes up with a P1316 misfire. I'm now totally lost. Any ideas?
Thanks in advance
Curley

 

Take off the 2 little screws on the MAF sensor and hose the inside where the 2 little resistors are hidden up that pipe with brake cleaner. Next I would “carefully” inspect all around the bellows of the air intake pipe and check for any cracks. There are other areas to check but that’s the first step. You can also search up rough running, misfiring, etc in the search bar of this forum and a whole slew of posts should come up. Most importantly, if you do something and it either improves or fixes it all together, please follow up with your findings on here to help current/future X308 owners.

 

Thanks... I'll try the mas today and I'll post the results.
Curley

 

I'm still dead in the water. I put the old coils back on and it's no different. I've checked as many hoses as I can, I've cleaned the mas, I've cleaned the throttle body and it now is very clean. That is without taking it off and cleaning the underside. Any help at this point would sure be great. It must be something crazy I'm overlooking. Could it be a cam sensor?
Thanks

 

It's more likely an air leak. You need a analyzer/scanner that can read fuel trims. There are many inexpensive ways to do this:
OBDII Code Scanners ** Member Approved ** - Jaguar Forums - Jaguar Enthusiasts Forum

 

When you adjusted/replaced the TPS, did you have a code specifically for the TPS?

Did you use a voltmeter or a scan tool to adjust the TPS?

Are there any other codes besides the P1316 when it goes into RP?

Just to clarify, the engine runs good when your driving/cruising, but when your at a stop and idling, the engine runs rough?

 

I've suspected it was something with the fuel, maybe injectors. Anyway, what are fuel trims and what will the scanner call that?
Thanks

 

I set the tp best I could from where the old one was. I couldn't find the correct setting anyplace. In the past, I've set them with a meter.

 

When I check the codes, all I ever get is the P1316 misfire. I put the old coils back in and no change. I've looked for days for a hose leak and can't seem to find any. I keep looking every time I go out... I'm tring to find out what fuel trims are. I've got a very expensive scanner and I'll check it again to see if it has anything about fuel trims.

 

Scroll down and look for “the dreaded P0147” thread. Read the whole post but I describe the fuel trims in post #12.

 

My son just checked the fuel pressure at the value and it reads 32 psi . Checking into it, it should be 40. I'm changing the pump now...

 

Today I took the car to a garage and his scanner showed mt fuel trims are way off. Could I buy just the solenoids and install them to correct this?

 

I just took the value cover off and found part of the tensioner then I found another part. The plastic fell or broke off. What kind of a job is it to replace the damn thing and do I need to adjust the cams? I know enough to get into trouble...
Thanks for your help....

 

Do not start that car until at least the secondary timing chain tensioners get replaced. There are tons of threads that you can search on how to replace them. I’ve never done it this way but there’s what’s called a “zip tie” method. Search for that in this X308 section. You will not have to adjust any valves. The hardest part is jacking up the front end high enough to safely get to the bell housing and removing the crankshaft position sensor to get the engine jigged for the timing marks.

 

I took my car to a good garage and the mech there is a buddy and scanned the car again. He found the fuel trims to be crazy off. He told me of a BMW he had that had the same problem and gave me a few suggestions. When I got the car back home, my son, also very smart on cars, suggested we remove the value covers and see what was going on. BINGO! He found the cam tensioners were visibly a mess! Plus, he noticed the flats on the cams didn't line up on one side like they did on the other. So, a days labor and a lot of parts later, the car runs better than ever! Thank you all for the ideas and suggestions. I felt I had to post this for others. Hope my bad luck helps others...
Curley

 

Interesting: after five years or so of a hiatus on secondary tensioners causing timing problems, we are starting to see this issue again. Must be a new batch of cars hitting 50 or 60k miles . . .

 

Probably still had the original ones in it. If new owners aren’t aware of them being an issue, they won’t know what to look for until it’s too late. Curley is extremely lucky not to have ruined the engine.