XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

1996 Jaguar XJS TPS

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Old 01-07-2021, 05:43 PM
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Default 1996 Jaguar XJS TPS

Background:

Jag started to bog down upon acceleration.....Almost ended everything???? Pulling onto the highway

1. Cleaned MAF
2. Cleaned IAR
3. Cleaned Throttle body

Jag now runs good again ....BUT....Still a little nervous

NOW ONTO THE TPS........

What is the procedure for cleaning the TPS once removed from the throttle body.

1. what pins on the connector do I check across
2. am I measuring resistance, if so, what are the values ( From idle condition to full throttle) I am looking for?
3. Do I need a special cleaner? I have carb cleaner, mass air flow cleaner and electronics cleaner. Do I need to be careful while cleaning with
the amount of cleaner used?

Some time ago I posted a thread regarding a possible less expensive TPS.....Unfortunately No One on the forum had any information regarding possible low cost replacements...other than used.

Still open to what you think about low cost replacements

Thanks

Softball60/Paul
 
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Old 01-07-2021, 06:11 PM
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There are no known low cost replacements.

There's nothing to clean. There are three pins, I've never had a problem with the contacts themselves, but because of the temps, my wires became a little crunchy. Re-wired using GXL wire and even a new connector with new pins and I'm at 0.0 LTFT.

There's really no good way to bench test a TPS. I've had one that bench tested perfectly, using an analog multimeter....but it forced the engine to maintain a 10.2% LTFT. Once replaced, it went down to zero.

You're looking for volts. 0.6v at idle. (unless it has been reset using a PDU/WDS, then it's whatever number it was reset to, but it will be very close to 0.6v. About 4.5v at WOT. I forget which two of the three wires you need to probe. Ignition needs to be on, but the engine doesn't need to be running, I believe....
 
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Old 01-07-2021, 06:54 PM
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Vee,

I saw a couple of videos being bench tested. It wasn’t an XJS TPS but it shouldn’t be any different. I really am not comfortable testing the un it on the car.

Are you saying it cannot be tested on the bench?

Thanks

Softball60/Paul

 
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Old 01-08-2021, 01:10 AM
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Originally Posted by Softball60
Vee,

I saw a couple of videos being bench tested. It wasn’t an XJS TPS but it shouldn’t be any different. I really am not comfortable testing the un it on the car.

Are you saying it cannot be tested on the bench?

Thanks

Softball60/Paul
It can only be bench tested providing you have the correct voltage source. The pre facelift 5.3 litre V12, for instance, runs the TPS with a 5 volt source from the ECU. So you need a 5 volt source to bench test it.
 
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Old 01-08-2021, 02:12 AM
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Since you mentioned MAF, I automatically went 4ltr I6, correct,??, as there no mention of the engine you are dealing with, and most of us in here go XJS = V12, but V12 no got MAF.

The I6 TPS gets soaked in oil mostly due to gravity, and oily goo build up that never gets cleaned out of the throttle body.

ALL mine responded to a good Carby Clean spraying, and working them back and forth on the bench. Refitted, replaced the oil filter (removed for access), and all sweet, and that was YEARS ago.

I clearly was lucky with this "set up" I keep reading about now, and knew nothing of, back in those days. All I knew was NEVER turn on the Ign with the TPS unplugged, so I did not do that.

This was on XJ40 and X300 cars.
 
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Old 01-08-2021, 06:50 AM
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Thanks for the responses,

I have heard that the USA had only the 4.0L imported that final year.

Is the TPS for the 4.0L the same as the 6.0L?

Thanks

Softball60/Paul
 
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Old 01-08-2021, 07:11 AM
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As far as I know, and also used as the replacement for the 3 leg 5.3 unit, until Bourns started making the 3 leg again. recently.

It just helps to have vehicle details somewhere in the thread, like the Sig section, then misleading info is minimal. We dont know all the USA, Euro, etc oddities, anymore than the those members know all the odd stuff we got, thats our responsibility to inform.

I saw some on ?bay the other day for $145US, cheap by what we paid for the 5.3 unit back before ?bay was invented, damn.
 
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Old 01-08-2021, 07:24 AM
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Originally Posted by Softball60
Vee,

I saw a couple of videos being bench tested. It wasn’t an XJS TPS but it shouldn’t be any different. I really am not comfortable testing the un it on the car.

Are you saying it cannot be tested on the bench?

Thanks

Softball60/Paul
You CAN bench test it....it just won't be conclusive. Like I said before, my TPS bench tested perfectly, but ended up being the cause of consistent overfuelling. Only after replacing it, with no indication that it had gone bad, was I able to resolve my overfuelling issue.

If you read through posts, and there are many, you'll find others who had similar issues, where the part seemed to work fine....but didn't.

I know it's an expensive part, but if it's original, then perhaps it's just simpler to buy a new one...it's done it's part for over 25 years.
 
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Old 01-08-2021, 10:16 AM
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The test/adjustments for the 6.0 and the 4.0 are completely different.
On the 6.0 the voltages only need to be balanced and voltage +/- is irrelevant.
When I got my 4.0 I couldn't keep it running at all.
I finally found the problem was an air leak around the MAF and the air filter box.
 
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Old 01-08-2021, 01:54 PM
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My problem with the TPS on a 145,000 mile 95 4.0 was that it was physically worn. It tested fine, but was notchy as heck.

If you’re in New England, I do have the machine to set the TPS.
 
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Old 01-08-2021, 02:49 PM
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Thanks for the responses,

Grant, I will make sure it is clear in the future regarding engine size.

For the moment with what I have accomplished it seems to be back to it’s old self and running great!!

I will tear apart and clean if it starts to act up again.

Softball60/Paul
 
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Old 01-11-2021, 08:31 AM
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Your XJS has an OBD so all TPS testing is done by using live data through OBD(key in position 2 or when running). Depending on the scanner TPS operation will show either in V or %, if its in V then from ~0.6V to as close to 5V as its possible. If in % then from ~11.5% to as close to 100% as possible. Due to vehicle age, throttle linkage stretch and the max TPS value at WOT will go down and its not uncommon for the TPS to show as little as 4.2V at wide open throttle and this greatly affects fuelling and can make car sluggish and underperforming so best to check your OBD data.
If you ever decide to remove it, you MUST record its OBD value at throttle closed and make sure to put it back to exactly the same position so it shows exactly the same voltage, if you dont, you'll have high rpm idle and yes, despite how it looks and how its attached to TB, there is ~0.1V adjustment in the bolts/holes. If you wont match the base voltage or base voltage is out of spec, you'll need to do a TPS adaptation with IDS/PDU.
I think only similar TPS that might be ok to use on AJ16 is one from early nineties Sierra but don't think anyone here ever tried it, I certainly will if/when the time comes.
Also, the AJ16 MAF can only be really cleaned if you drill out the rivets and take the actual MAF element out of its case, then you can replace the rivets with small screws.
 
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Old 01-11-2021, 01:41 PM
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I spent far too much time looking at potentiometers and alternative options before I bit the bullet and bought the red TPS.

What’s your time worth? Are you retired?

Originally Posted by Softball60
Background:

Jag started to bog down upon acceleration.....Almost ended everything???? Pulling onto the highway

1. Cleaned MAF
2. Cleaned IAR
3. Cleaned Throttle body

Jag now runs good again ....BUT....Still a little nervous

NOW ONTO THE TPS........

What is the procedure for cleaning the TPS once removed from the throttle body.

1. what pins on the connector do I check across
2. am I measuring resistance, if so, what are the values ( From idle condition to full throttle) I am looking for?
3. Do I need a special cleaner? I have carb cleaner, mass air flow cleaner and electronics cleaner. Do I need to be careful while cleaning with
the amount of cleaner used?

Some time ago I posted a thread regarding a possible less expensive TPS.....Unfortunately No One on the forum had any information regarding possible low cost replacements...other than used.

Still open to what you think about low cost replacements

Thanks

Softball60/Paul
 
  #14  
Old 01-11-2021, 08:26 PM
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JigJag,

I’ve seen the RED unit but it’s for a different vehicle????

I am retired and have lots of time!!

What are you proposing?

Thanks

Softball60/Paul
 
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Old 01-12-2021, 09:10 AM
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Can someone please tell me where I can find the procedure for mounting and resetting the TPS on my 96 xjs.

My old age is catching up with me.................!!!!!
I replaced my TPS several years back but misplaced the written procedure. On the 96 xjs it does not require special equipment to accomplish.

It is a matter of turning the ignition on and off several times for a required amount of time and performing certain things.

Thanks

Softball60/Paul
 
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Old 01-12-2021, 12:44 PM
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Mounting, or resetting?

To reset, you'll need a PDU, WDS, or some kind of OBD2 software that is specifically designed to reset the Jag TPS.

Now if you replace the TPS and make sure that the voltage reading matches the one you took out, before you disturbed it, then you should be fine. Ideally the TPS is at 0.6v at idle, but yours may be slightly off due to age. You'll need the car turned on (engine need not be running) and then run a multimeter between two of the three pins. You need to do this in situ, not removing the TPS nor the throttle body.

When you install the new TPS, make sure it locks into the throttle body at the exact same voltage. If you mess it up, your idle will be too high/low and you'll need a reset.
 
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Old 01-12-2021, 05:11 PM
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Vee,

As always thanks for the input.

I have replaced the TPS in this vehicle (1996 XJS) once before. It was a used good spare to replace the original.

I removed the problem unit and replaced with the spare. There is a known Jaguar procedure to do this not requiring any electronics to adjust. It basically was a process...for lack of a better explanation....it is a manual reprogramming of the ECU. After the TPS is installed, the procedure involves starting the engine and a series of on /off times. It gets the ECU to recognize the TPS and reprogram the system

It took a couple of tries but the engine settled in and ran perfectly for several years.

This process/procedure is what I am looking to acquire. I can’t find the old one I had documented.

As of right now car is running great but I am trying to get ahead of the curve should the TPS finally fail.

Thanks

Softball60/Paul
 
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Old 01-12-2021, 06:03 PM
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Originally Posted by Softball60
JigJag,

I’ve seen the RED unit but it’s for a different vehicle????

I am retired and have lots of time!!

What are you proposing?

Thanks

Softball60/Paul
I was working up a 4:1 gear reduction adapter to allow readily available, high quality, 1-turn 5K pots to be used in this application.

3D designed CNC’d cage from Weerg, steel or maybe delrin spur gears.

if I’d carried on I would have made it reduction-gear-adjustable-in-place with a custom plug for attaching a multimeter without disturbing the cars connection.

In the end I decided to buy the TPS and move on. Pandemic and work are enough at the moment. Retirement sounds nice.
 
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Old 01-13-2021, 09:56 AM
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Originally Posted by Softball60
Vee,

As always thanks for the input.

I have replaced the TPS in this vehicle (1996 XJS) once before. It was a used good spare to replace the original.

I removed the problem unit and replaced with the spare. There is a known Jaguar procedure to do this not requiring any electronics to adjust. It basically was a process...for lack of a better explanation....it is a manual reprogramming of the ECU. After the TPS is installed, the procedure involves starting the engine and a series of on /off times. It gets the ECU to recognize the TPS and reprogram the system

It took a couple of tries but the engine settled in and ran perfectly for several years.

This process/procedure is what I am looking to acquire. I can’t find the old one I had documented.

As of right now car is running great but I am trying to get ahead of the curve should the TPS finally fail.

Thanks

Softball60/Paul
I've been on these forums for about 11 years. I've gone through these forums endless amounts of times looking for solutions to issues. I even ended up finding a PDU and now own one, as well as a WDS, and I can assure you there is no way to reset the TPS on these cars without some hardware loaded with Jaguar specific software.

You MIGHT be thinking of the alleged way to manually reset the Idle Air Control Valve (IACV). While it's included in the service manual, it will not work on the AJ16 engine, at least not with a 96 ECU. That procedure involves turning the car on and off while unplugging and re-plugging in the IACV sensor three times. It is useful in helping determine whether the IACV is failing, but it does not reset idle permanently in the 1996 AJ16 engines. The car will return to the high/low idle after turning the car off and restarting it.

Perhaps it works on the 1995 ECU, more likely the AJ6 engine.

If there was a manual way to reset the TPS, it would save every AJ16 owner a lot of headache, and it would render the PDU and WDS much less valuable/useful to most owners. To have the ability to reset the TPS, has for me, already made all the money I've paid for the PDU back, in lost time and spent money.
 

Last edited by Vee; 01-13-2021 at 09:59 AM.
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Old 01-13-2021, 05:01 PM
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the cheapest way to do the TPS reset at home is to buy a used rotunda VCM and run IDS, you can find a working genuine for around 250 bucks. works great

ive heard if you wait it out it should find the correct idle after a while (weeks, months?). as a temp fix you can just unplug the ICV in the cold start idle position and leave it there.
 

Last edited by xalty; 01-13-2021 at 05:06 PM.


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