Auto kicks down way too soon.

[geoff]

I have been trolling the wewb for weeks trying to solve a problem I have been having with my 3.1 td MU Wizard and thanks to our friends on the ITOCUK forum have found a fix.

Basically the auto has been kicking down when even a slight bit of xtra throttle is used. This has resulted in the thing changing down unexpectedly at speeds over 100kph and on hills usually results in me ending up in 2nd doing 30kph while trucks, cars,cycles and old people on mobility scooters flash past.
Extremely frustrating as you could imagine.

It turns out the cause of the problem is electronic, not as a couple of shops told me, a stuffed auto.
The part in question is TPS (throttle position sensor) mounted on top of the injector pump ( see pic ).
This is made from a conductive plastic and acts much like a potentiometer giving a varying voltage depending on throttle position.
Problem is, the wiper that contacts the plastic is made from steel and eventually wears away the conductive strip and results in the auto changing down when it shouldnt.
The fix is simple ie either change the TPS for a new one, or, as can be seen in the attached pic, the sensor can be rotated counter clockwise slightly, thereby giving the wiper a clean unworn contact to work on. If you rotate too far you may get a check trans light or O/Drive light flashing.


You can get the full story here:

http://www.itocuk.co.uk/forums/viewtopi ... sc&start=0

Hope this helps someone as it certainly sorted a few of their cars

Cheers

Geoff

[geeves]

good find

[bonkers]

its going to help me tonight when i get my car back..thanks and great find..

[bonkers]

Does the 2.8lt MU have the same or are they done by a kick down cable...??

[geeves]

dont know but they are the same auto

[bonkers]

it worked it worked.....i adjusted the tps a couple of mill and it seemed to work fine now...great find and a big thanks to all...Time will tell if it solves the problem for good..

[bonkers]

well i towed my boat last night ruffely 1300kg for around 35-40minutes and it was very hot outside it was going fine until the A/T oil temp light came on. I stopped the car and turned it back on the the light went off as i was at my destination not long after. On the way home same time travel it happend again first it wouldnt go into OD then the light came on.. Today it ran like shit couldnt find a gear so now its time for a gearbox service and a transmission cooler hopefully that helps. Time to put in the manual,!!

[geeves]

no auto in any car is going to regularly tow that sort of weight without additional cooling. Add to that the temps youve been haveing in Melbourne. Hopefully its just fluid and filters.

[Blondini]

Forget the service you have just stuffed the clutches in the box and will need a full rebuild.
I have done this and will never own a auto again.

[geeves]

You might be lucky although the chances are not great. The service guy will know when he opens the pan. If theres friction material in the pan you get a big bill.

[bonkers]

i had fitted a front mount trans cooler a while back very small but after 1hr into the first tow i cool feel the auto giving up (not going into top gear) so i have since bought a much bigger front mount cooler off ebay and should do the trick....where do i find the filter on this thing..?

[Rusty92MU]

excellent my auto just started changing down to and for some reason wont go into overdrive unless i speed up and take my foot off the acc and then it changes for a bit other wise it stays down a bit i might give this ago and see if it fixes it.

[bonkers]

yeah mine did the same thing...give it a service and some transmission reconditioner (stop slip) and adjust that sensor...it works...!!

[nighthawk]

My TPS sensor is buggered I think, anyone know where I can get a new one or can one be modefied of a diff engine?

[bonkers]

holden mite have them if your willing to give up a leg....just try a holden rodeo wreckers..

[geoff]

Glad to see this helped some people. I was beginning to think about giving up my mu until I found that article. Another bit of advice that seems to come through really strongly is to treat it with Lucas Transmission Fix. Available through Supercheap and repco in NZ. Lastly, the others have been changing the trans filters and putting in new oil to good effect. The trans filter is accessible throught the belly pan of the auto. Apparently in the UK its not available as a replacement part so they are dis-assembling the filter to clean and then putting it back in. We shouldnt need to do that over here as I think they are available as a spare part.

[geeves]

If you have trouble getting the filter. Jeep uses the same as do some toyotas.

[shylie]

is it normal for the auto to drop back to second when goin uphill?? my auto seems to hold second till around 85ks, but only jumps into 3rd for a moment b4 goin straight to overdrive. and its the reverse when accelerating, it seems to go straight from overdrive to second, which is not a good thing!! i couldnt pass an old hino on a moderate hill ... after reading this thread im hoping these ideas may fix mine as well.

[shylie]

just an add on,i have the "92" 2.8td and i had to know if this would help my problem, and wouldn't you know it, IT DID , i went straight outside with my trusty torch and done the adjustment as suggested and the results were instant. i've only driven in town for the moment but the difference is noticeable and tomorrow ill take her for a run out the highway and hopefully the results will be just as good. GEOFF you are a LEGEND , great post!! you have most likely saved quite a few people some rather large (and unneccesary) repair bills, myself included. thanks again!!

[geoff]

Mate, thats awesome.....glad it helped