Hey Gang,


For the last several days, 50% of the time that I start my 99 XK8, it revs very high and vibrates a fair amount while still in Park.

I shut it down, and at restart, 90% of the time it's just fine again.

However, I can tell when driving it, that there's still some slight vibrations going on similar to a misfire or a dirty spark plug.

My first instinct would be to check the spark plugs and the wires, but that doesn't explain the high RPM at start-up.

I properly cleaned the mass air flow sensor (replaced 4 years ago), and it didn't help at all.

I just took it out on the road, and went heavy on the gas petal, and it immediately went into the Limp mode. Pulled it over and re-started it, and it went out of Limp mode, but still acting the same as before.

I just plugged in my code reader (Advanced Actron), and no codes came up whatsoever.

Any ideas out there?

 

It could be the fuel just add a can of BG44k to a full tank and see what takes place. I have a process of cleaning the TB down to the plugs and you may try that. When was the last time you replaced the plugs? Have the tensioners been replaced?

Link JagRepair.com - Jaguar Repair Information Resource

 

Gus,


Great hearing from you! You've always been a great help!

Yes...tensioners have been replaced.

Plugs replaced less than 6 months ago (while doing some other routine maintenance).

Is your TB cleaning process in your 'How-To' pages?


Thanks in advance,


Tom

 

Not sure if it is in the How To but the link is direct to it.

 

Sounds like it could be an air leak. Look at fuel trims.

 

Thanks to all!

Even though the plugs were changed 6-8 months ago (not by me), I replaced the rust-ringed Bosch spark plugs today with NGK's, and the cat now runs just like it's supposed to.

That doesn't give Bosch a lot of credit, does it?

BTW...each plug looked normal for each cylinder when removed.

Strange if you ask me, but I'm not complaining as it was a cheap fix (I don't see that very often).

 

Were those Bosch Iridiums? I was going to get those for my '97 but I wont now.

Dave

 

I have been using Bosch in both of my cars for years and never had a problem with them. I would still add the BG44k to clean the injectors and valves.