Build Mitsubishi 4D34-3AT3B diesel swap into 94 FZJ80

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So, relocating the thermosensor had no effect (as I feared).

I checked the resistance of the thermosensor against the table in the manual and it was in range, and it changes with the increase in temp. I also checked the resistance of the line pressure solenoid and it was within range. I then checked the shift solenoids just for kicks, and I got no continuity for the timing solenoid.

This is weird, because the computer should sense the lack of continuity and flash code 33, but I am getting a fairly consistent code 24.

According to the Isuzu manual the timing sensor as no effect on the lockup, but I am thinking that the lockup is probably dependent on line pressure, and the timing sol. could have an effect on this. The diag tables in the manual are not very good either, since they don't even mention temp as a possibility for lack of lockup.

I'm going to post on expedition portal in the Fuso section and hope that someone has the correct manual because without the actual Fuso manual for the trans, this is getting a little ridiculous. The truck works fine with no lockup (and I have not really noted any weirdness due to the possibly non-op timing sensor).
 
When trying to bring my transmission up to temp, I just park the truck up against an immovable wall and leave it in drive. Within 15 minutes, the transmission was warm enough for the torque converter to lock up.

Applying 12 volts directly to the lock up solenoid should cause the torque converter to lock up. When I was trying to sort out my transmission wiring, at one time I got things crossed up so I ended up 12 volts on the lockup solenoid continually. If I stopped the rear wheels from turning, the engine would stall.
 
That has been my experience with lockups as well. I posted on the expeditionportal site and I think I have the correct manual coming. From what I understand the timing solenoid reduces line pressure when shifting, so as to minimize the shock. If it was stuck partially open (piece of crud or something), I could have a line pressure leak that would cause off shifting and not enough force at idle to engage the lockup clutch. I could also have an internal transmission issue. I am just going to wait until I can confirm the fault code before I move ahead any further.
 
SuperHatch said:
On a separate topic, what is the function of the warmup switch? Does it keep the glow plugs on? I don't have mine hooked up right now... (the switch, not the plugs)
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My nissans (also controlled by a Zexel ECU) raise the idle to ~1500rpm and I think open the EGR valve too, or did while the EGR valve was still hooked up. It makes a big difference even with EGR blanked.
 
On the Isuzu, when the engine is cold, in addition to controlling the glow plugs, the QOS controller may apply the exhaust brake to put a load on the engine and may also close a butterfly valve in the intake to richen the fuel ratio, all to help warm up the engine.

There doesn't seem to be an direct connection between the actions of the TCM and the QOS.

Edit: The intake butterfly exists on the 4HE1, not the 4BD1/2.
 
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So, code 54 was indeed for the transmission timing sensor. I replaced it with a spare and the shifting is noticeably firmer. I think it was working originally and stopped working fairly early on. The most noticeable change is how it downshifts, much firmer and more positive shift. Still no lockup but the fluid level was low when I went for a test drive and I will re-test once I top it up. I will also try the +12V test on the wire for the lockup solenoid to see how it reacts, now that the timing sensor is working.
 
Fromage said:
So, code 54 was indeed for the transmission timing sensor. I replaced it with a spare and the shifting is noticeably firmer. I think it was working originally and stopped working fairly early on. The most noticeable change is how it downshifts, much firmer and more positive shift. Still no lockup but the fluid level was low when I went for a test drive and I will re-test once I top it up. I will also try the +12V test on the wire for the lockup solenoid to see how it reacts, now that the timing sensor is working.
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Well that's good to hear! Like I said, the lockup is definitely noticeable, no doubt it is happening. Like Astr said, it is like a 5th gear shift.
 
So you've been running on low line pressure for a month or so?
It's a hastel, but maybe worth a look at the trans filter?

Loving the follow up and details of these diesel threads you guys have goin, please keep it up.
Cheers,
 
Still no lockup. I took it for a long drive, I even blocked airflow to the trans cooler with cardboard to make sure it got up to temp. Nothing. No fault codes, no issues, it works perfectly but it just does not lock up. I have not yet done any testing to see if the shift solenoid is now getting power or not, nor have I bypassed the computer and given it 12V to see if I can engage the lockup.
 
Fromage, have you hooked up a test light to the TC lockup solenoid circuit?
 
Sorry to be belligerent here, but after this weekends events with my 62 I can verify that a clogged trans filter will/can reduce line pressure enough to prevent converter lock up on a a440.

I know you have no tach yet, but mine drops about 400rpm at 54mph and it is noticeable in the seat of the pants.
Are you able to hook up a pressure gauge to a trans cooler line, or get a digital pressure signal from the trans computer?
 
Pacer said:
Sorry to be belligerent here, but after this weekends events with my 62 I can verify that a clogged trans filter will/can reduce line pressure enough to prevent converter lock up on a a440.

I know you have no tach yet, but mine drops about 400rpm at 54mph and it is noticeable in the seat of the pants.
Are you able to hook up a pressure gauge to a trans cooler line, or get a digital pressure signal from the trans computer?
Click to expand...

I would doubt that Fromage has a clogged screen because he just finished rebuilding the transmission. I could understand that this could be a problem after 100K miles.

You should see almost no pressure on the trans cooler line at the output from the transmission unless your cooler or lines are plugged. The return ATF from the torque converter (hottest ATF) is routed through the cooler and then just dumps back into the transmission pan.

If you want to see if the TCM is commanding a torque convert lockup, just connect a 12 volt lamp or LED to the wire that goes to the lockup solenoid and ground. The torque converter should be locking up when the light comes on.
 
astr,
Understood and agreed, thank you for the reply.
It seems to me, from the experience Fromage describes, that the TCM is not receiving the 'okay' to initiate lockup.

What does the TCM look for before it allows 12v to the lockup solenoid? Speed (you've tried that one), line pressure, gear selection? Whats missing?
Is it possible to send 12v directly to the lockup solenoid? Maybe through the exhaust brake circuit?

I want to see this resolved, I feel Fromage has come so far and is missing the real joy possible from this setup... I bet with the trans working properly one could see 28mpg out of one of these rigs you guys are assembling here... if you could stay out of the skinny peddle for a full tank, maybe I'm dreaming...
 
I did a series of tests that haven't really confirmed anything so I suspect I have a valvebody issue. The first test was the +12V to lockup, which made no difference. Second test was to put a light on the solenoid lead to see if the computer was switching and trying to get the trans to lockup. It never came on, so it looks like the computer is not trying to shift into OD.

Looking at the table in the manual, it looks like line pressure is the only thing that could affect both mechanical and electronic functioning of the trans. Since I've pulled the pan and used up my last gasket, I am going to wait and swap out the valvebody with my spare 450-43LE one, with a new filter.

I have a sneaking suspicion that I have an internal valvebody leak. I am hearing a funny noise from the trans area that I had assumed was the belts slipping for the alt (the alt I am using is huge). It sounds like a high pitched whine on startup, and I think it might be pressure escaping from a blown gasket or something along those lines. I have a feeling the timing solenoid issue has something to do with it.

Also, having now studied that manual and all the possible fault codes, I am almost certain that the A442F with a 450-43LE valvebody and converter can work and not trigger fault codes. There seems to be no fault code that looks at transmission slip or mismatched engine RPM and output speeds. The gear or lockup related fault codes are related to shift solenoid resistance only. So, if any of you are thinking about this swap, I think it would be worth it to just use the A442F with a 450-43LE valvebody and torque converter and controls. I think it would work very well. I am actually tempted to try it (if I could find a complete A442F).
 
Fromage, I agree, when my 440's filter clogs the pump wines and line pressure drops. I can tell it's coming on because I can hear the pump before any other symptoms are noticeable.
Good luck, I think you're on the right track.

There is an fj80 sitting in a wrecker's yard here in Philadelphia. TCase is gone, but 442f is still there...
Maybe I should pick it up since mine is clearly on it's way out...
 
Fromage said:
Also, having now studied that manual and all the possible fault codes, I am almost certain that the A442F with a 450-43LE valvebody and converter can work and not trigger fault codes. There seems to be no fault code that looks at transmission slip or mismatched engine RPM and output speeds. The gear or lockup related fault codes are related to shift solenoid resistance only. So, if any of you are thinking about this swap, I think it would be worth it to just use the A442F with a 450-43LE valvebody and torque converter and controls. I think it would work very well. I am actually tempted to try it (if I could find a complete A442F).
Click to expand...

Couple of question on this note: Does the A442F have lock up and would the TCM be able to control it? Would the power button still work and could it be hooked up to the ECT button I currently have?

Thanks
 
Muleysam, you would use the valvebody and computer from the Fuso and the trans from the Toyota. The A442F has lockup and the Fuso computer has a power/normal setting, so that could work fine. In my rig all the buttons work as per factory, I have the OD/no OD button and the power/normal button.

All this is only possible because the A442F and the 450-43LE are so similar.
 
Pacer said:
Fromage, I agree, when my 440's filter clogs the pump wines and line pressure drops. I can tell it's coming on because I can hear the pump before any other symptoms are noticeable.
Good luck, I think you're on the right track.

There is an fj80 sitting in a wrecker's yard here in Philadelphia. TCase is gone, but 442f is still there...
Maybe I should pick it up since mine is clearly on it's way out...
Click to expand...

I've got all the stuff on order and hopefully I can tear into it next weekend. I hope you are right, the trans does seem to shift a bit differently than before. I am going to swap the valvebodies straight across and change all the gaskets, seals and triple check everything, hopefully that solves it. I definitely think that the lack of lockup is what's keeping me right at 18-20 mpg.
 
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