The 1999 Jag I have has no check engine light on. It will go in to fail safe mode if more then %75 throttle is applied. I think it is the TPS because I can trigger fail safe mode with the vehicle turned off and key on while I depress the throttle. My question iswhat is the most common link to the fail safe problem? Andhow often do the tps sensor's go bad and also is there a factory repair manual I can down load off the Internet for free?

 

I checked TPS % with the engine off and key on and it seemed to be fluctuating from 2% up to 8% so I think I'll change the sensor and cross my fingers.

 

Be careful as TPS is a calibrated part to your throttle body. Not normally serviced seperatly. Did you have codes? If fail safe engien mode is illuminated, it will give you a code.

 

Well I didn't want to hear about the calibration thing. I try to avoid the dealer as much as possible, can a snap on scanner calibrate the tps? I have no check engine light on so I didn't search for a code. Does the computer have to get flashed to calibrate the computer or is there a easy procedure?

 

you might need a throttle body.. i think snap on will get a code. but no description

 

I dont mean a calibration via software. It is bolted to the throttle body in a set position.

Just because CEL is not on doesnt mean there will be no codes. If you have a snapon scan tool you may be able to read codes. Try and read them when failsafe engine mode is showing on the cluster. Do not turn key off, just read the codes. Let me know what they are.

 

Dealer said I cant get the tps by its self I have to get the whole throttle body. Looks like I'm going to send it to the dealer for a diagnosis before I spend the big bucks.

 

If I get a used throttle body is there any programing involved?

 

Codes
P0121

Pending
P0121
P1000
P1637

Sounds like a throttle body to me. What's your thoughts?

Thanks.

 

well the throttle body 's are like 2000.00-2500.00

 

Genius you still have that throttle body in your store?

 

no but i can get them. what year is the car? old style throttle body or new?

 

I located a used throttle body plus intake for $400. Or supercharger and I'm assuming it comes with the throttle body for $750 =). What's involved with putting theSC on this engine? Is the engine harness the same just with a different ECU for the SC?

 

You dont want to retrofit it. Alot of work.

Genius it is a 1999 i think.

I would advise againt buying a used throttle body. If Genius can get one for you, I would buy that.

 

1999 Vanden plas XJ8 4.0

 

im assuming vacuum assist?

 

I'll check tomarrow. Is a 2003TB the newest used TB that will interchange on my 1999?

 

It may not. I forget when they chenged them. Can you post a picture of it?

 

http://i69.photobucket.com/albums/i7...dio/jagtb2.jpg

http://i69.photobucket.com/albums/i7...dio/jagtb1.jpg

From the looks of the bolts for the throttle cable bracket it has been taken apart once.

 

I disconnected the battery, and then took it for a drive at WOT and no fail safe. I wonder how long this will last.