Isuzu Trooper Owners Club UK™

[mutlley]

just done a road test. needs fine tuning, but other than that, seems to change quicker, seems smother but that might just be me. when slowing down the check trans light flashes. not done a motorway trip yet, the big test will be m6-61 spilt going south. that stretch towards m65 drives me up the wall with the car changing when it wants. will be watching this topic closely. and i will let you know soon what its like with c/van on.



 

[Google]

[MartQ]

Hi Muttley,

If you set the sensor up using a voltmeter, you should get no flashing lights at all, and the shift should be a lot better too.  I found setting it nearer 0.3V at idle better than at 0.5V.
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94 Big Horn 3.1 Lotus Auto
Torque Flung Dirt Technique!

[mutlley]

will do. thanks.  

[Hard1]

Yeah I reckon if you got the light flashing whilst moving you may have gone too far although mine never did even when cranked right around. Try it with the meter and let us know the result. I just did mine by, er, luck and no flashing light (except when stopped) so I'm leaving be for the moment. If you have turned it almost fully CCW then it will change up quicker, but that's not a good thing really especially if it's harder to kickdown.

Like I said previously, if this erratic behaviour is the result of wear and tear, everyone is going to see different results - so it's going to be a trial and error job.


The key really is the kickdown characteristic and you will definitely find that out on a motorway. Good luck....
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1999 Cougar with a NICE motor..

Click HERE to see under my bonnet!

[Hard1]

ttt
_________________
1999 Cougar with a NICE motor..

Click HERE to see under my bonnet!

[mutlley]

ttt..........................?


 

[Hard1]

To

The

Top

But even I had put TTB (to the Bottom) it would still have worked....
_________________
1999 Cougar with a NICE motor..

Click HERE to see under my bonnet!

[mutlley]

still waiting to get my multi-meter back, so far the time being its where it was before.  ttt.  hopefully get it done soon, cus now i know there is a cure.........

how is your auto-box doing hard1? are you still impressed?

 

[Black Rider]

I do a lot of towing with my '93 Bighorn and thought that it kicked down in overdive top a bit too soon but after watching this thread for a while I didn't think things were as bad as some of you were saying, so I had a look at the position of my throttle sensor and guess what - it's almost all the way anti-clockwise already. Some previous owner has already made the adjustment so I'll leave things alone!

[Hard1]

Hey there Mutley. Not only impressed but using the motor a lot more now and buying bits for it again. To be honest, I had lost so much confidence in it I just dumped it outside really and never used it (I have a "work" vehicle too).

The "fix" has transformed it. I just hope this thread helps someone else too as there's a lot of peeps out there that had the same complaint.

Interesting comment from Black Rider. There has to be a reason that adjustment was put on it, and may be a clued up garage altered  it. I  suppose eventually the TPS will "wear out" completely (see earlier posts on this thread) but until then, this little 2 min tweak saved my Bighorn from the classifieds.

Onwards and upwards!

Disclaimer: Just because it worked for me doesn't it follow that it's right for everyone. Please verify parts and modifications for your own use before jumping straight in. Happy Trooping.
_________________
1999 Cougar with a NICE motor..

Click HERE to see under my bonnet!

[mikeeboy]

How are you guys who have done the mod getting on?
Thinking of doing it myself soon, as that kick-down is a bit pants
Found this link which might be of interest
http://forum.australia4wd.com/index.php?showtopic=6869
Mike

[Hard1]

Hi there, all working fine.

Thanks for the tip that the TPS might be available seperately. I know for sure that MartQ and I would be very interested in acquiring one.

Mart, if you're watching, this is from an OZ guy with a Jackaroo 3.1 auto

"The TPS or ITP sensor can be tested without the tech 2 tool as it is a simple potentiometer. but dont use solvents to clean it (plastic components).
They are a common failure and can be purchased separately for approx A$80.00. Dont let them tell you you need to buy the entire throttle actuator assembly. "

So what we need to do is talk to someone from Oz, or maybe NZ?

Back to the subject of altering the TPS, do it in stages and drive it a bit to see what it's achieved. I certainly don't regret altering it.

Remember that while you will notice a significant improvement in kickdown behaviour, the TPS will also affect the upshift (if you go too mad, it won't kickdown at all and you'll be in top gear in a very few seconds), so it's a balancing act.

If you do alter it, please report your findings back to this thread.

Cheers and good luck....
_________________
1999 Cougar with a NICE motor..

Click HERE to see under my bonnet!

[MartQ]

Mines great now too, no problems.  Set the voltage at idle to 0.3V and everything works great with no flashing lights.

The item described on the Oz site is for a carbon film component, whereas the ones fitted to ours is a conductive plastic so using solvent cleaner is a no no, even if it doesn't damage plastic it would compromise the contact patch between the plastic track and the wire brushes of the "wiper" part.  Once these wear out, that's it, you can't make them any better.

I'm still waiting to hear from Variohm ltd about potential replacements.

It's interesting though that Isuzu/Holden/GM/whoever, sell the sensors down under but are quite hapy to fleece us for a complete throttle body.

In answer to some of the questions on the Oz forum, in case anyone is interested:

Yes they can be tested without a Tech2.  The best thing to use is an old fashioned analogue multimeter on ohms setting.  Across the two outer plug conections you should get a reading in the region of 5000 Ohms, doesn't need to be exact.  

Connect between the centre connection and one of the outer connections and simultaneously turn the shaft of the sensor.  The reading should vary up or down (depending on which of the outer connectors you are using) between 5000 Ohms (ish) and zero ohms (short circuit), although, again maybe not totally down to zero.

The actual Ohm values are not that important but should be in the region stated.  What is more important, and the reason it is best to use an analogue meter (one with a needle rather than a digital readout) is that the transition when you rotate the spindle is smooth and the needle doesn't fluctuate or flutter at any point as you turn the spindle.  i.e. if you start at zero, it gradually and smoothly increases to 5000.

As the sensor's track is made of conductive plastic and the wiper is a wire brush, they tend to wear out around the throttle position where most of the mileage is done.  60mph or roughly 2/3rds throttle for example if you spend a lot of time trundling up the motorway.  This causes a fluctuation in the resistance at that point and confuses the control box into thinking you have stepped on the throttle, thus causing it to kick down.

Cor, I do go on don't I?
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94 Big Horn 3.1 Lotus Auto
Torque Flung Dirt Technique!

[Hard1]

No mate that's exactly it. The more we understand it the more we are likely to find a solution. The "problem" occurs with mine at exactly 60 mph (or it did before I wangled my TPS). It simply did not know what to do..change up or down..and it usually did both, many times which was why I felt like taking a hammer to it.

There are some NZ members on here, I wonder if they also have access to a new TPS? $A80 is roughly £40 here so time it's landed that's going to be in the er, £75 bracket.....ish....
_________________
1999 Cougar with a NICE motor..

Click HERE to see under my bonnet!

[Hard1]

Here's an enterprising NZ site, parts of Isuzu 4JG2 repair manual downloadable for £5 each category!

Nice work if you can get it. Yes, there is a "repair manual" on the TPS for a 4JG2 listed.

Can it be repaired? I don't want to spend a fiver and all it says is "chuck it out and buy a new one"!   Which is what I'm betting on, but all the same, I'm curious...

http://repairmanual.co.nz/afawcs0112305/Chapter=5845/ID=356/Manual=323/index.html
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1999 Cougar with a NICE motor..

Click HERE to see under my bonnet!