Automatic playing up, tryin to make sense of it. GQ

[flashrx2]

hi all, i have a 92 gq ti 4.2 efi patrol.
i am wanting to check operation of all electrical components of the auto and am wondering if the manual i downloaded from here is relavent to my model car or not?
i have the power auto hold switch on the dash.
when doing self diagnosis the power light just stays on but i am not sure if the manual suits mycar.
and then when checking power at the tcu nothing is making sense.
my problem with thecar is when you are say just wanting to cruise down a slight hill with very little throttle to hold speed, the auto drops back to 3rd gear. as soon as a little more throttle it drops back into 4tho/d converter locks up fine, so it seems to me anyway. if you get off the throttle all together it just coasts as normal. seems to be just real slight throttle at hway sorta speeds.
hope this makes sense.
i have just changed fluid and filter, flushed most old oil. auto changes alot nicer now but still has the above problem.
when i bought the car the oil level was low and leaking from pan gasket.
thanks in advance.
ashley

[04OFF]

Ash, Check if you have a cable kick down, a electronic switch on the accelerator pedal, or the other trigger can be vacuum related

It sounds like the auto is getting told to kick down too early in responce to a slight bit of pedal, so it triggers (changes down) at 1/4 throttle instead of 3/4 throttle etc.

[flashrx2]

hey steve, i am pretty sure the tps tells the auto wot to do, it may jusy need a slight adjustment.
i just didnt wanna mess with it till i have a bit more knowledge on the subject. these boxes have electrics everywhere! need a c4 or a turbo 350. would be much easier.
thanks mate

[04OFF]

Bwaha, yeh missed the EFI bit, straight away just thougt GQ = carby, ok ive had a few beers haha !


Yes the TPS will be variable type then, have you checked with a multimeter it is set at zero fully closed throttle, perhaps someone has increased/adjusted the idle with the butterfly stop screw instead of the air bypass valve, this is a common mistake and will make the TPS think the throttle is cracked even though you are closed throttle.

Maybe check the throttle body butterfly stop screw see if its been tampered with, check the butterfly is closing to the correct spot, also check for carbon build up and exessive shaft freeplay, you probly done all this already ?

[flashrx2]

checked these items and adjusted tps and air bypass valve, made no difference to problem made the auto shift later but. also found that there is no difference when turning o/d off or turning on power switch. remains in 4th gear, no kickdown.
not sure if maybe tcu damaged as well as box needing rebuild. maybe i need to post this elsewhere to get more lookers at my thread?
thanks so far steve.

[flashrx2]

so i take it that nobody can answer any of my questions?
any info would be apreciated.
even the auto in my 80 series was less troublesome.
so complicated for a simple kinda car.

[taslucas]

I suppose firstly you need to know if it actually is a problem or if it's how it's ment to operate.
You said that adjusting the tps made it shift later but didnt fix the problem. I thought the problem was that it was shifting too early?
Mark where the tps was then it doesn't matter how far you adjust it because you can always put it back. I have the carby model so my tps is on the carby. I only have to move it 5mm or so to feel a big difference in when it shifts.


FanTapstic!

[flashrx2]

the problem isn't shifting early it is shifting back to 3rd gear when coasting to maintain speed on flat or slight descent on hwy. a bit more throttle slots it back into o/d.
also none of the other buttons seem to make a difference to wot it does.
I am curious if there is a manual to cover the auto on an efi gq patrol.
I cannot find any similar threads on here.

[Clunk]

When you press the switch to Power, does it rev higher and longer than when the switch is on Auto? When switched to Hold, does your auto try to change gear either up or down when accelerating or decelerating?

I only asked because when mines in power, it holds onto the revs longer before shifting up when accelerating and if I remember rightly stays in gear during acceleration and deceleration with Hold depressed.

[04OFF]

Im just wondering if you can check the cold start sensor operation for the ECU, normally i dont think the gearbox is allowed into overdrive until the eng is up to full running temp, but i think once up to hwy speeds it may overide this even when cold.

Not really sure it if could cause your exact issue, but might be worth investigating so you can rule this out as problem ?


Im a bit concerned that the OD button does nothing, do you have a OD light confirming the switch is working ?

[flashrx2]

all the switches lightup like there is power there but they make no difference to operation. not sure bout cold start yet. is a bitch to start wen cold, takes a few goes and doesnt rev higher anyway once started.
the joys of buyin a shitter. doesnt bother me that much, just need totinker wen i get a chance.