Today I replaced the old, faulty Bournes throttle position sensor with the new type, Jaguar-approved, which included a well-made retrofit adaptor made of aluminium.

I have been trying to troubleshoot the car's surging engine and unsteady idle for some time, but was not prepared for the efficacy of this fix.

It's like the engine has had brain surgery! It runs smooth as silk and idles like a clock. Gone is the surging at 40mph and the bucking, galloping tendency that has plagued the car for so long I can't remember.

Also, the instant fuel economy indicator shows that the car is getting WAY better mileage, which you would expect with better engine manners.

This was about the best money I've spent on this car in ages.

OK, I'm going to go drive the car some more.

 

Hey blackjack, sounds like a great fix

Thanks for sharing.....How about a little more info as I'm sure this will interest many such as pics ( if possible ) and detail on part numbers / pricing etc and maybe where you purchased it from?

Any / All info will be much appreciated I'm sure as this seems to plague more than a few Jags

 

Happy to share that, Jim!

The part number for the kit is 03-2500 and it is available from xks.com. When calling, ask for Steve at ext. 227.

The kit comes with the new-type potentiometer which plugs directly into the old harness with no mods. Also included is the aluminium adaptor, which is a finely-machined piece, and a "gender adaptor" (because the old TPS has a female input to its shaft, and the newer type has a flatted, male shaft).

The unit comes with no instructions, but it's pretty self-explanatory. It's $318.17 for the kit which includes the TPS. Also, if this TPS ever goes bad, the replacement is $125 so that's a lot easier to swallow. But from what I understand, this one is pretty darned tough.

It's a genuine Jaguar retrofit, so no "brand-x" worries.

Incidentally....The post-mortem on the old, original Bournes TPS revealed a static resistance for the control of 3.7K ohms. However, when turning it from idle upwards, there was a spot that went open-circuit about 1/3 the way into it, and also totally erratic readings from the unit exceeding 10K ohms as it was turned up! No wonder the ECU had no idea what the engine was doing! I'm surprised the car ran as well as it did with this faulty component. The unit also had tons of sideplay in the rotating piece. Shot!

All the surging is now completely gone and the idle is rock steady. It's like driving a new car! It really tamed the devil out of this one.

 

I have a similar situation w/ my '04 XJ8 VDP, in the surging at slight load uphill at about 30 mph. my jag dealer in ft. worth hasn't been able to figure out the problem over the past 3 years, and i'm wondering if the TPS could also be the culpret in my case? any ideas? Thanks, Dave bedford, Tx. 114,000. mi. ALSO, to save space 2] my gas gauge only shows just over half full when i fill up, and it vasilates on starting asn works it's way up to that mark again after a few miles.