Dear friends,

Hello again. Today i have received a used throttle body where the TPS never has been disassemble. So, i have replaced the throttle body that I installed with a new TPS and i have installed the new throttle body with its TPS without to have been removed.

So, i was hoping that problems with the high speed was solved, but the problem persist although now, rpm is around 1.200-1.300 rpm at idle.

I have thought that maybe the problem is that throttle body is not hermetic (although i have put silicon around the the throttle boy joint, but not much) and maybe air enters through the metal joint. Do you know if this can do a high speed at idle??

Thanks

 

From what I have read , no seal , metal to metal

 

On the subject of vacuum leaks look at the hidden line attached to the backside of the fuel pressure regulator . Otherwise look all over the intake manifold .

 

I cam confirm it’s metal to metal. I have put on a little gasket dressing on the mating surfaces for the hell of it. Nothing permanent, and nothing that cures.

 

Throttle and TPS position and voltage it gives at idle are paired with the ECU so for this to work without any adjustment you would need to replace both(from the same car) at the same time.

Your TPS at idle lets say currently gives 0.6V but the idle voltage value stored in your ECU is lets say 0.54V. This means that they are out of sync and ECU thinks you have your throttle slightly open and your stepper motor never works hence the high idle.

To fix it put the car on the ramp and start it up. From underneath the car undo slightly the TPS screws/bolts. There will be enough play within the holes to move it either side by maybe a millimetre, that's enough for the TPS voltage to move by 0.10V and enough to adjust it and get it in sync with the voltage value currently stored in your ECU. When you get it right, tighten up the TPS. If you cant get the RPM right then it means that the TPS voltage value for idle stored in your ECU is badly out of what it should be and you'll need to reset it in IDS, WDS or PDU or try to replace your ECU.

As a quick workaround you could also get the stepper motor extended fully and unplug it(it extends automatically, I think when you move the key to position 2, wait few seconds and then switch it off, cant exactly remember how its done though). Although not ideal, it would get the RPMs set at ~800.

I can also confirm its metal to metal, although a bead of instant gasket wont hurt.

 

I have the same problem too unfortunately. Was this issue never solved??

 

With respect to whether a gasket is on the IAC valve is in question

From my understanding there should and maybe just maybe if it is missing the IAC final idle position may compensate for no gasket

Vee had a procedure on the IAC valve calibration without removing it ( bolts can snap on removal

There was an example that the TPS value was high like near the 0.70 Dc volts range and the ECU learned that this is the new null

This would make sense that the ECU would slowly learn a " drifting " sensor like the O2 sensors

Do you have a EGR that can be cleaned in the poppet seat ?

The EGR valve has a position sensor to verify it has arrive at it's commanded position

Or a ELM 327 device can see EGR_Error perimeter target value 0 % in all throttle / load ranges

You can also see the EGR position at idle with a simple meter of X volts on the Y color wire

Although the 0 % is ideal but can't be expected in real world

 

dead track in a tps does this

buy a new one from jlr classic run throttle adapt no more problems

 

No EGR valve on mine..

Funny thing is I had similar issue a few years ago. Bought a made in china LHE1640AA and it lasted basically 5 minutes. Cleaned up the old sensor, and it lasted until recently. Tried again to buy another cheap LHE1640AA but it didnt work.

So I bought an original from Jaguar at 240usd and now it runs for 15 minutes and then the same problem happens again. I have over the last 7-8 years also changed most of the same parts mentioned the owner of this thread, so I am a bit puzzled..

 

To test the TPS directly and know it is the issue there are 2 ways , one person operation or two person operation :

To see the 0.60 DC volts or abouts reading through the TPS rotation sweep you would nick the insulation on the Green / Yellow wire from the still connected TPS connector as that wire runs over the fuel rail

The valve cover is not a good ground point

Slowly very slowly rotate by hand the TB butterfly shaft and with the key in the run position but engine not started you should see the voltage very smoothly increase toward 5 DC volts

The two person test is through the ECU connector on socket Red 11 and Red 12 with the ECU connector removed , no key in run position

In this test you will be looking at resistance as a very smooth change since your circuit will not be powered by the reference 5 .0 DC volts

Pic coming

 

On socket Red 11 , 12 , and 7 verify the sockets have the 2 pinching tabs intact that grip the ECU module pins / blades

 

Bed time in the US

 

Office time in Norway

 

Pulled a coil and noticed both some oil residue down the well and some white stuff inside the coil. Tip of spark plug looked good though..

The coil is just a year or so, but a rather cheap ebay coil. Replaced with an old, original i had as a spare, and now it runs again. At least it did for my 30 minute drive.. fingers crossed it is fixed. But will have to look at the oil leak..

 

There was some discussion a while back of wrapping the coils in Kapton tape as a high temp insulator

This would help the arcing to the coil well walls

Might be on need of new O - ring seals as the wells mate with the cylinder head surface

Both easy to find through places like E - Bay

The large around the perimeter seal of the valve cover has some variations on manufacture accuracy as your choice as a package deal to include the well O - rings

This effects your large seal area of the valve cover

There is a D shape cutout on the very back edge valve cover seal that you would have to feel with your finger that it did not fall out of place on assembly

There is an issue with the corners of the D's needing to be filled with high temp silicone as form a gasket may not be temp rated high enough

Just covering the base if you go that direction

 

05-1-35 (jagrepair.com)

 

The white stuff is dielectric grease.

The oil is coming in from a failing cam cover gasket. You have a large gasket that goes around the perimeter, and six rings that go around each spark plug.

Easy to fix.

I recommend using the OEM gasket for the cam cover, but you can go aftermarket on the six plug hole rings.