Took tank out to fix fuel level sender and replace pumps. Never a P0121 before. First start after tank back in P0121 and failsafe engine mode pops up after few hundred feet of driving. Turn off and restart. Failsafe returns in a few hundred feed. Go to workshop manual and search "throttle position sensor" and
Pinpoint Test V entitled DTC P1240, P1241, P1242; SENSOR REFERENCE VOLTAGE MALFUNCTION, HIGH/LOW VOLTAGE (THROTTLE SENSORS, FUEL TANK PRESSURE SENSOR) comes up. Pinpoint Test V (attached) goes into checking voltage and residence of TPS. Don't know how but it appears my P0121 may be related to the tank out/in. Thoughts?

 

Had just written above post and was about to go to bed when I though hard reset. Went out and did hard reset. Took for a spirited drive and no more P0121,

 

Sorry to say but it may be back on a 2nd or subsequent warm up.

 

Sounds like you have a potentially weak TPS. Probably wouldn’t hurt to get one so you have it on hand.

 

Doesn’t look like Denso TPS made anymore. The normal places like FCP AND Autohauz don’t have. One used Denso on eBay for $250. Amazon and eBay have many no name knockoffs for as low as $25. Reliable brand and where to get?

 

I bought a new cheap one on eBay a while back. I was skeptical but, I used it on a customers car to diagnose their bad TPS and it worked during many heat cycles and miles. It’s certainly better to have than nothing at all.

 

Code came back with failsafe. Do the XJR and XJ8 take the same part 198500-3250?

 

Found a post stating they both take the same one. Chime in if disagree.

 

I feel they are the same PN as well.

 

If you ever need to check this sort of thing, I find the Jag classic parts website helpful. You can look up the part for whatever version of the car you're looking at & compare part numbers.

https://parts.jaguarlandroverclassic.com/

 

JLR will only supply an entire TB PN vs a TPS PN which isn’t available separately unless you buy a Chinesium TPS.

 

Ordered a $33 no name off Amazon. See if that works. Will try to find a Denso at a salvage yard. Coincidences happen but concerned never before and happened first time after tank work.

 

Why are the TPS bolts female 5 point? Looks like buying another tool.

 

Torx fitting.
Apparently it makes it quicker & easier in the factory as they don't slip or miss as much as traditional screws or allen heads when the robots are slightly out of adjustment.
There's a security version too, with a raised pin in the centre. Get those as they also fit the normal ones so you won't need two new tools when you finally encounter them as well.

 

The tool bit is called TAMPERPROOF TORX PLUS and whatever size the bit needs to be.

 

Not surprised torx, surprised 5 point. Ordered set off Amazon last night.

 

2003 XJR. With old TPS, live data absolute throttle position 0.0% rest and 5.9% floored. New TPS 3.9% rest 68.6% floored. Hooked scanner up to my XK8 and results 3.1% and 100%, With new TPS in, starts up and bounces off 3000 rpm with no pedal input. I think that is the rev limit when in park. Interestingly no more restricted performance/fail safe.
Before started attacking this issue car would go between running like a bat out of hell and then go into restricted performance and run at maybe 1200 rpm in drive with no pedal input.
Further mistifying is intermittenly (with key on) butterly does not move with throttle application. One time got a pending P0122 throttle/pedal position senson/swith 'A' circuit low.
Does live data absolute throttle position come from PPS or TPS?
I'm think I put the new TPS correctly per pictures below.



This is original TPS. Could see wear marks on black plastic so side of metal tab my nail is touching in prior picture is slid in on side below metal pick.

 

Try this, some people believe it should reset TPS.

1. Turn the ignition key to the on (not start) position.

2. Press the gas pedal to the floor (depress kick down switch) and hold for 10-15seconds.

3. Turn the key to the "off" position (don't remove the key), then release the gas pedal.

4. Wait at least two minutes for ECU to reset.

Keep drivers door closed the entire time.

 

Tried. No go.

 

I've seen some posts that after installing a new TPS car needs to be reprogrammed using special software. True?