Our TB's don't seem to go long without replacement. How long did you'rs last? My car has 22,000 miles, with a p0121 code, and even if cleaning it solves the problem, I'm thinking of having it rebuilt anyway, so I can take a long trip and not worry about it. I understand the rebuilt is better than original. I'd like your thoughts. Thanks ......mick

 

I sure hope you're wrong about the life span.

 

I came from the carburetor days where it was apparent that there were things that wore out, mainly due to the gas that ran through the various ports and jets and wearing out of the gaskets.

But a throttle body is just a big air pump and for the life of me I cannot figure out anything that would "wear out". Perhaps bearings on the butterfly shaft? The bore does get gunked up over time but that should be easily cleaned. My last car was a 1995 Corvette and I do not believe the throttle body was EVER removed or tinkered with for the 15 years I owned the car. I would just do the occasional cleaning of the bore with some off-the-shelf spray.

Doug

 

The additional item, and the critical item is the TPS that is part of the throttle body. No one seems to know a cross between that part and a generic part. What happens is the electrical contacts and sliders wear out.

 

These were available separately for my Corvette as was the IAC control. Is that not the case for the Jaguar?

Doug

 

Apparently not. There are a couple of threads moaning about this, and a few more attempting fixes by disassembly and tweaking.

There must be a part, because the rebuild houses must have them, but no one is saying what the cross would be.

It might be the Toyota Avalon because someone has mentioned the similarity except that pin polarities are reversed. If true, that is not really insurmountable.

 

I thought I'd read somewhere in the many posts on this topic that the position sensor was stamped with the Ford logo............?

Graham

 

That would be nice .. but which Ford?

 

I have the old TB from my 2001 XK8 in a box somewhere in the back of the garage. If I take the position sensor off, do you have any lookups for numbers?

Graham

 

good old internet ... even assembly numbers are findable if you isolate junk terms enough

 

I'll dig it out later and get any numbers off it.

Graham

 

Also grab any manufacturer text on it.

 

Graham,
Without wanting to sound too much like the Giant in Jack + the Beanstalk - be it live or be it dead?
I'd love to know the resistance between the two ends of one of the pots and between one end and wiper at closed and WOT and I don't want to tempt Providence by messing with mine (currently working).
Although it would be really good if there was a sensibly priced TPS out there it is only a dual gang pot - perhaps €10 for a real quality one.
I'm not even sure the value is that important since it is just acting as a potential divider.

 

I thought I read somewhere the TPS was made by Denso & was similar to one used by Toyota.

 

As Plums said there is apocryphal reference to the pinouts being reversed.
I was looking at the Denso MAF in my old Toyota diesel and it looked identical to the Jaguar one, connectors and all.

 

Steve,

It died on a wet November night on the A69 between Carlisle and Newcastle-upon-Tyne. Amazing how an otherwise busy road can become absolutely deserted once you breakdown.

Graham

 

This throttle body has a precision stepper motor to run the throttle butterfly, and there are two throttle position sensors that talk too each other and the requisite air passages .
It is also heated by the cooling system to prevent icing and help with fuel atomization. Although compared to a DCOE Weber or big Dellorto, the parts don't look too complex, but with the systems they are attached to together are very sopisticated, much more so than any carburetor.

 

The Denso MAF sensor in our 2004 Lexus RX330 SUV is identical to the MAF sensors in both of our Jaguars. I pulled all three of these MAF sensors out for cleaning at the same time a few months back. Lined them up on a rack to spray them with MAF cleaner and I could not discern any visible differences among them....

 

Looking at the wiring there are two pots feeding a voltage back to the ECU which is proportional to how far the stepper motor has opened the vane.
From reading around there is a failsafe so that if the two voltages are significantly different the ECU spits out its dummy.
As Plums says this happens if one wiper goes bad or the pot track breaks down.
It will be nothing more than a twin gang pot, presumably linear law.

 

Those who said DENSO, step up for a prize.

There's rotational adjustment available on the relationship of TPS to TB



The top fixing bolt is paint marked, presumably to check it hasn't been touched in the event of a warranty claim.

This is the drive arrangement with the TPS removed:



Part numbers on the face of the TPS:



The one above the DENSO label reads 06019H.

Nothing in the way of numbers on the inside face of the TPS:



There's no obvious way of getting into it:



No break lines in the plastic housing and no securing screw hidden under the DENSO label.

Graham