2004 M1123 TPS Sensor problem?

[Squirel]

Okay, so I have a 2004 M1123 with a NA Meltons 6.5. It has the electronic 4 speed transmission. I have been trying to figure out why it wont go above 45 mph. It starts up instantly every time. I replaced all the glow plugs. Every single one of them was burnt up, but it still started and ran fine at idle. However under acceleration it feels like it has no power and will not go above 45. I raised it up and all the wheels spin easily and freely so the brakes are not dragging. I did all the fuel system checks. It has fresh fuel, I replaced the filters, and bled the air out of the system. I did find that the return fuel line check valve by the tank was in backward and leaking. That still didn't fix it. So yesterday I had to back it up quite a ways to get to a place where I could turn it around. It felt like it was running great. Then into drive and it felt like it had no power again. So I start thinking maybe its the transmission. It's not throwing any codes other than the standard ones. It is not in "Limp Mode"

So here is where I am...
When driving it it will shift through all the gears but only into 3 and 4 when I let off the accelerator. I am thinking that maybe the TPS is incorrectly adjusted or faulty. As soon as I "get on the gas" it kicks down. I am thinking that this is why it will only do 45 MPH.

Now the big question. Does anybody have the test equipment (TPS Block Gauge, TPS Test Cable, and Diagnostic Switch Cable) for the TPS that I could borrow? I read that there is also a training video on the TPS so a link to that would also be great. I think this might have been the problem all along and could possibly be a quick and easy fix. Anybody have any insight?

 

[AAVP7]

Okay, so I have a 2004 M1123 with a NA Meltons 6.5. It has the electronic 4 speed transmission. I have been trying to figure out why it wont go above 45 mph. It starts up instantly every time. I replaced all the glow plugs. Every single one of them was burnt up, but it still started and ran fine at idle. However under acceleration it feels like it has no power and will not go above 45. I raised it up and all the wheels spin easily and freely so the brakes are not dragging. I did all the fuel system checks. It has fresh fuel, I replaced the filters, and bled the air out of the system. I did find that the return fuel line check valve by the tank was in backward and leaking. That still didn't fix it. So yesterday I had to back it up quite a ways to get to a place where I could turn it around. It felt like it was running great. Then into drive and it felt like it had no power again. So I start thinking maybe its the transmission. It's not throwing any codes other than the standard ones. It is not in "Limp Mode"

So here is where I am...
When driving it it will shift through all the gears but only into 3 and 4 when I let off the accelerator. I am thinking that maybe the TPS is incorrectly adjusted or faulty. As soon as I "get on the gas" it kicks down. I am thinking that this is why it will only do 45 MPH.

Now the big question. Does anybody have the test equipment (TPS Block Gauge, TPS Test Cable, and Diagnostic Switch Cable) for the TPS that I could borrow? I read that there is also a training video on the TPS so a link to that would also be great. I think this might have been the problem all along and could possibly be a quick and easy fix. Anybody have any insight?

I have all those, but am a bit far away..... Just in case nobody locally volunteers: In a bind, all those items can be replaced by makeshift gear:

The thickness of the block gauge is given in the TM, so you can make your own.
The test cable is just a convenient way to measure voltages. It can be replaced by a voltage meter with needle sharp contacts, so you can poke them through the insulation of the regular TPS cable.
And the Diagnostic Switch Cable is just a convenient way to short two contacts in the diagnosis plug on the TCM. I don´t know the letters off the top of my head, but if you search for "4L80", they will show up.

I agree that with your symptoms, and the tests you already did, the TPS is a prime suspect.

 

[Retiredwarhorses]

You issue is not an engine issue, but a trans issue, are you sure the trans is not in limp mode?
have you manually shifted through all gears?
is the trans lamp on when in the run position ?
is the trans lamp off when running?

 

[Squirel]

You issue is not an engine issue, but a trans issue, are you sure the trans is not in limp mode?
have you manually shifted through all gears?
is the trans lamp on when in the run position ?
is the trans lamp off when running?

Pretty sure it is not in limp mode. It does shift. I can feel it shift 1-2 and then if I let off it will shift into 3 and 4
I have manually shifted from 1 to 2 and 2 to drive and drive to overdrive. Same symptoms.
Trans light comes on in run/wait.
Trans light turns off when engine starts.
Thank you everybody for your suggestions.
I tried turning the TPS clockwise toward the front. It did not seem to fix the issue.
My next step is to get in there with my multi-meter and see what its outputting.

 

[Squirel]

Well, It's been almost two years but I finally got motivated to figure this thing out and it was not the transmission. It was the timing on the injection pump. It looks like the pump was replaced at some point and they never timed it. There was a mark on the block but no marks at all on the injection pump. It's not fun to get the bolts loose but once I did I was able to play around with rotation and found a spot where it runs and drives pretty well. Glad I can finally drive this thing. It's a blast.

 

[Action]

Well, It's been almost two years but I finally got motivated to figure this thing out and it was not the transmission. It was the timing on the injection pump. It looks like the pump was replaced at some point and they never timed it. There was a mark on the block but no marks at all on the injection pump. It's not fun to get the bolts loose but once I did I was able to play around with rotation and found a spot where it runs and drives pretty well. Glad I can finally drive this thing. It's a blast.

The right tool makes things easier...

 

[Squirel]

The right tool makes things easier...

Oh yeah, I spent the $100 on the wrench set, it still sucked..