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Discussion Starter #1
Hi!

My 91 Turbo doesn't kickdown (among other things it doesn't do), and as I'm fairly sure it's the TPS that's at fault, I've ordered a new one.

I bought a Hella 6PX 008 476-001 for 30€ - electrically the same as the Bosch one, but 1/5 of the price. Made in Germany too!

Question:
On my car the TPS is mounted with the connector pointing down. I was under the impression that the connector had to point up?! Which is correct?

How do I adjust the new TPS? Have the throttle fully depressed and then turn the TPS until the gearbox clicks?

Cheers

Es
 

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Discussion Starter #2
Connector pointing down is correct!

How does one adjust it correctly? Listen for a click from the gearbox on full throttle wirh ignition on but engine not running?

Es
 

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I did not found any procedure for adjustment or even replacement of TPS :/ Do it really need adjustment? Are there not round holes for screws that allow adjustment?
Eventually it is needed to find other car with late Bosch KX-Xtronic and check its manuals...
 

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Discussion Starter #4
Hi!
The TPS Sensors have elongated holes, so can be adjusted.
As far as I understand, there's a definite signal fir kickdown when the throttle is fully open, and another for idle when the throttle is closed. Not sure what the area in the middle does....
I'll try googling some other brands with KE-Jetronic to see what the procedure is there!

Es
 

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As you have new TPS in your hand you can confirm if there are only two switches or additional potentiometer? If only switches, adjustment should be not so hard?

Did you check with multimeter how works (or does not work) your current TPS??
 

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Discussion Starter #6
Hi!
I had a fiddle with the TPS yesterday, and I can confirm that it's indeed just a switch.

Mine also seems to work, so I've left it in at the moment. It's potentially also a pain to actually change, at least without removing lots of bits.

When I fully depress the accelerator pedal (with ignition on, but the engine not running), I hear a click from under the ECU cover, but nothing from the gearbox. I thought there was supposed to be a loud-ish clack from the gearbox, or am I wrong?

Also, there is an old-fashioned kickdown switch below the accelerator pedal. What's that for if the kickdown is actuated by the TPS?

Cheers

Es
 

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As far as I know, the old fashion switch under the carpet is essential for the kickdown.
If you do not press it with the accelerator, there is no kickdown.
Make sure the carpet is not blocking it.
 

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Discussion Starter #8
Hi Jean!
I was under the impression that the kickdown was actuated by the TPS! I read that somewhere on here I think....
Does the old-fashioned switch for directly to the gearbox then?
The carpet is indeed an issue...
 

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Kickdown is accomplished with the switch behind the pedal. It activates a solenoid in the gearbox to re-route the fluid.
I have never heard of a kickdown activated via TPS.
 

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Discussion Starter #11
Thanks guys!
Makes more sense to me too, but I did read the "TPS-theory" either on this or the Australian forum!
Should there be an audible click or clack when the switch is actuated?
Where are the wires that go into the gearbox located?


Cheers
Es
 

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The Bentley Heritage site has your Bentley listed with parts diagrams.
It is a very useful site with TSB's as well. Become familiar with it.
The kick down solenoid is located where???
In the transmission....because it is responsible for fluid movement.
 

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Discussion Starter #13
Hi!
I'm familiar with the heritage site, was on it regarding the TPS.
I know that the valve is inside the transmission, what I was after is where the connector or cable is. I'm presuming that the kickdown switch sends a signal/voltage to the gearbox, and I want to test that!

Cheers
Es
 

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Discussion Starter #16
Wraithman,
My transmission is not a 4L80E, but a 3-speed! Is it then a regular TH400, or has the Rolls-Royce version been modified?
 

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THM 400 are all the same, same like on Silver Shadow.
Make sure that your throttle pedal is pushing the old switch, that is often a problem, otherwise the trnasmission will not receive the order to change gear.
 

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Interesting.. I see 91's using the 4L80E.

Have you looked at the pan diagrams to confirm the shape, that would be the easiest?
 

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The kickdown connector is a simple 2 wire connector on the linkage side of the gearbox casing.
 

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Discussion Starter #20
Thanks!
We just had it on the lift, and I cleaned the 2 connectors - and the car now has kickdown :)
Thanks guys!

Cheers
Es
 
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