Mitsubishi Delica Owners Club UK™

[bulldoggy]

Hello are you sitting comfortably,

After reading a post regarding torque converter lock up and the fact that at about 65 mph, when you put your foot down, the only thing that seems to happen is that the lock disengages and the revs go up  I decided to have a go at the suggested insertion of a variable resistor on the throttle position sensor (tps) on the fuel pump. So off to maplins I went and got myself a variable resistor and some wire (so that I could put it easily accessible).

Located the tps and tested the terminals on the connector found the 5v feed and guessed the one with the black tracer was earth, so bared the other one and stuck the volt meter onto it and got my son to slowly press the accelerater pedal. sure enough the voltage slowly increased, I.E this was the wire leading to the gearbox ecu. So I connected everything up and off I went, result = no change

So now I have a problem. I hit the web to find out how the sensors work, Found out that the sensor is basically a potentiometer that varies the voltage to the ecu. At a predetermined voltage the ecu knocks the auto trans out of lock up. Now basic 'O' level physics and a bit of V=IR made it clear that if the voltage was constant adding a resistor to the circuit would only alter the current output and the ecu works on voltage change not current change.

So off came the intercooler again, disconnected the resistor and removed it, rejoined the wires together and scratched my head. I had a good look at the whole set up and noticed that the tps had two screws holding it in place and that it seemed to be adjustable. So I loosened the two screws and twisted the sensor as far as it would go in the direction of the movement that the accelerater cable exerts on it. Tightens it up reassembles the intercooler and off we go.

Well wow; what a difference down the hill to the Island and we hit torque converter lockup I floor the throttle and pure acceleration beautiful. gets to the roundabout takes my foot off the pedal and the transmission warning light comes on - blow. Head off back up the hill home on a wave of torque however notice there's also no kickdown above about 50 so maybe towing up hill may be a problem. Anyway gets back home gets out the old volt meter remove intercooler and checks voltage at idle from the signal wire and no voltage, so I figure that the ecu needs a voltage at all times from the tps to tell it that all is well.

I adjusted the tps a little to give a voltage which was about .25 and reassembled the intercooler and off we go.

First three gears as normal; well they would be only the overdrive is controlled electronically. I then get the lockup and away we go however still no kickdown. So i head off home and whip the intercooler off again turn the tps a little more and reassemble and away we go.

Now after lock up I can get the pedal almost to the floor without it disengaging the lockup but if I push the pedal hard down it comes out of lockup brilliant    


So if you want to have a go It's well worth the effort. A few tips : If you put a cloth over the battery you can rest the intercooler there, avoiding having to disconnect the wires for the fan and temp sensor.. Two bolts are sufficient to temporarily hold the intercooler in place, You do have to do up the jubilee clips on the intercooler pipes because one blows of if you don't.

So In summary the car now uses the torque loads more than it used to. acceleration is great and the gearbox now seems better suited to the diesel engine that it is mated to. As far as I can tell none of the other functions of the gearbox are affected. :D

PS spelling or punctuation in this article do not need commenting on

[Google]

[Rusty]

Sorry mate you lost me just after the 'hello' bit

Seriously, looks like you were very patient and were rewarded for the effort. Hopefully others will be inspired 8)

Always been glad I've got a manual g/b because of the stories I've heard of the so called mismatched auto gear changes but if this tweak fixes that, then I may be converted

Oh yea and a very WARM WELCOME to the forum mate
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[chiefie]

just goes to show that a correctly adjusted tps, oh! and kick down cable can make a big difference to the drive.
there is a correct way to set it up but you seem to have done a good job by trial and error. :D

turbo pipes make a nice noise when they blow off, don't they

rik
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delicarik@hotmail.co.uk

[alan S]

Hi Bulldoggy

Brilliant work
can I ask what your final voltage setting was please as this may aid many of us that want to try this as well.
A little better torque placement may well help us that drag caravans


Regards
Alan
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Alan & Christine
94 Space Gear Exceeds
Green over grey deceased
Silver delivered
It's not DELICAte
founding member? of the rollover group

[rikyuu]

hello all,

thought I'd explain how the resistor modification to the TPS I invented works, just to clear it up (gotta degree in electronics so should know what I'm talking about!!).
I was helping out Bulldoggy by PMs to implement this on his Delica (thanks for the mention!!), but seems you managed to come up with a mechanical version of it instead.

PS. for further details, see my post near the bottom of http://www.MDOCUK.co.uk/forums/viewtopic.php?t=2488

The TPS is fed by 5v and ground. The output feeds a fraction of the 5v. ie. at the halfway point you get 2.5v. This is called a potential (or voltage)divider and it feeds into the gearbox controller.

There are formulas and calculations etc, but to avoid all that, it can be compared to a bloke (or woman) on a ladder. If the ladder is 100m long and the bloke is 50m up then you are half way up. (ie, the TPS voltage would be half of 5v). If the ladder is extended, then the bloke is no longer half way up. Say if another 50m was added, he would only be a third of the way up. This works the same with the TPS. If you add a resistor into the 5v feed, with the TPS in it's half way position, it's no longer half way up the total resistance (ladder). Therefore the voltage drops for the same TPS position. Hence the TPS has to move further to get the same voltage out. ie. you have to put your foot down more for the gearbox controller to see the same voltage and kick down.

That's why it works!!

hope this helps, if you want some equations just ask!!  :D