A442F downshifting lag

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C

Catchsash

10 Year
Joined
Dec 20, 2015
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22
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95
Location
India
Hi guys,,

I drive a 91 1hdt AT.
I am getting down shifting issues, it feels like it's not dropping down into the rite gears because of which I find lack of power. I tightened the kick down cable but get very hard shifts.
Also I get a gear slip or a thud shift when it is shifting from 3-4 in D and sometimes also in 2-3 in G3 position.

I have semi loud knocking sound when I engage the gears an I general I sometimes struggle with lack of throttle response.

Manual shift from L-2 is smooth but then problem stats after that

The fluid and filter are new and were changed around 15k kms.

Please advice on what I looking at, driving in this condition is pretty irritating.

Cheers
 
Have you tried to pull any codes from the tcm? Maybe some solenoid issue...
 
SeaJay said:
the 'kick down cable' is more a line pressure adjustment, that's why the shifts feel harsher. Try adjusting the TPS on the injection pump, that is what changes the shift points. Have a read of this
Click to expand...

Does teh manual IP come with TPS? Can you please share how to check this, everywhere I look it says there is no TPS in this one.
 
Catchsash said:
Does teh manual IP come with TPS? Can you please share how to check this, everywhere I look it says there is no TPS in this one.
Click to expand...
No the injector pump for a manual transmission on a 1HD-T will not have a Throttle Position Sensor.
Are you using the diesel automatic trans computer as well?
 
'91 HDJ81 will use a fully mechanical/hydraulic A442F, no electronics, so no codes to pull, no TPS to adjust, no ecu for the transmission.

Make sure the kickdown cable is adjusted as per the FSM, there's not a lot else you can do with these ones, it might be in need of a rebuild. Does it shift properly when you manually control it via the shifter? Can you elaborate on what you mean by "I have semi loud knocking sound when I engage the gears"?
 
IanB said:
'91 HDJ81 will use a fully mechanical/hydraulic A442F, no electronics, so no codes to pull, no TPS to adjust, no ecu for the transmission.

Make sure the kickdown cable is adjusted as per the FSM, there's not a lot else you can do with these ones, it might be in need of a rebuild. Does it shift properly when you manually control it via the shifter? Can you elaborate on what you mean by "I have semi loud knocking sound when I engage the gears"?
Click to expand...

The moment I slip it into D the engine starts to make knocking sound. Also when I stop the vehicle the engine still tries to pull the vehicle, it does not fall into neutral. I have driven a few modern ATs they tend to not roll when you are in gear and stopped in signal, mine tries to roll and I have to control it with brakes and that is when this knocking sound comes.
PS: sorry if my points come a little stupid, I am just trying to explain it as I see it
 
You should need to hold the brakes to keep the car from moving in D, I'd be more concerned if this wasn't the case. It should be easily controllable though, if the truck is trying to lurch forward while you're holding the brakes that's a problem. Neutral is a separate "gear" on the shifter, and it should not be falling into neutral unless you move the shifter there, I'm not sure what you mean by this.

The knocking noise is concerning though, makes me wonder if it's engine or transmission noise? Possibly an issue with the flexplate?
 
IanB said:
You should need to hold the brakes to keep the car from moving in D, I'd be more concerned if this wasn't the case. It should be easily controllable though, if the truck is trying to lurch forward while you're holding the brakes that's a problem. Neutral is a separate "gear" on the shifter, and it should not be falling into neutral unless you move the shifter there, I'm not sure what you mean by this.

The knocking noise is concerning though, makes me wonder if it's engine or transmission noise? Possibly an issue with the flexplate?
Click to expand...

I just got the engine rebuilt so I hope there nothing there. Looks like need to take it to some specialist now. Thank you for your inputs. Really appreciate it.
 
ok...1991 it should be an A440F tranny as A442F came out later and then it became A450...you are experiencing solenoids issues, the TPS IS atop the diesel mechanical pump (not electrical) is a black thing with two phillips head screws securing it, untighten and move ...

TPS.webp
 
panamacruiser said:
ok...1991 it should be an A440F tranny as A442F came out later and then it became A450...you are experiencing solenoids issues, the TPS IS atop the diesel mechanical pump (not electrical) is a black thing with two phillips head screws securing it, untighten and move ...
Click to expand...

Which tranny is fitted may be dependent on the market it was made for, or what part of '91 it was manufactured. My '91 HDJ81 had a non-electronic A442F. @Catchsash look at the VIN plate on your firewall and tell us what transmission it says your truck came with.

@panamacruiser The A440F is also a fully hydraulic transmission, so why would there be a TPS on the injection pump...there's not trans ecu? TPS came on the late '92+ HDJ81's with electronic A442F transmission.
 
I have read that even the A440F has solenoids, therefore may have some sort of computer somewhere...if the dash has an ECT switch then is the A442F or check your PRND if it is the A442F it has an O/D button if it is the A440F then it does not thus being PRND32L instead of PRND2L
 
panamacruiser said:
I have read that even the A440F has solenoids, therefore may have some sort of computer somewhere...if the dash has an ECT switch then is the A442F or check your PRND if it is the A442F it has an O/D button if it is the A440F then it does not thus being PRND32L instead of PRND2L
Click to expand...

There's 2 versions of the A442F, earlier versions were fully hydraulic, later ones were electronically controlled. I've owned both. There is no change in model name to differentiate between the two. The fully hydraulic version has no shift solenoids, it is fully mechanical in operation.

You are correct that if the truck has the ECT button and O/D button then it's the later, electronically controlled version.
 
From Wikipedia

A440F
Type: Full automatic 4-speed transmission with converter lock-up. Fully mechanical / hydraulical control, no electrics or electronics. Mechanical throttle control input for kick-down function. Connects to external oil cooler. Uses ATF-II. Application:

  • 1985-1992 Land Cruiser
A442F
Application:

 
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