Okay, thought I had it fixed, but no dice.

The truck starts perfect, idles perfect, no smoke, but only has about 10% power. I only has enough power to barley move. It had a crank sensor code so I replaced that. Still nothing. I tested the throttle (apps) sensor and had the right voltages, so I was told it was the VP44. I replaced that today, and it still only has 10% power. I replaced the fuel filter and checked the LP pressure. I get 19 psi at the VP. I am out of ideas. It does not have any other codes???????

Any ideas? I have spent a lot of money so far and nothing has changed.

Looking for help,

Thanks,
Jeff

 

How did you test the APPS?

 

Voltmeter on #3 wire, ignition on, .5 volts at idle position, moved throttle through full throttle and it gradually moved up to 3.5 volts.

Thanks, Jeff

 

1. How about the fuel filter?
2> Is your fuel jelling?

 

he said it has a new filter, and he has 19psi at the vp, if the fuel was gelled he'd have little to no fuel pressure.

just a shot in the dark, is the tranny slipping? you never said if it would rev up or not, if you load up the engine what kind of rpm do you get.? I'm outta ideas, as it sounds like you have replaced/tested all the normal culprits

 

How does it feel if you rev up the engine in neutral? Does it smoothly accelerate right to redline? Not sure if you have an automatic or not, but I'm wondering if the problem could be there?

 

sounds like trucks in limp mode, what kinda shape is the wiring harness going to the injector pump?

 

New fuel filter, not cold enough to gel here.

If I put it in neutral, it will rev up. If I put it in drive and do a stall test, the engine just gets off idle and the turbo barley spools up, then just sits there.

It was suggested that it is the Torque Converter, but the engine does not even build up boost pressure so I dont see how that can be.

It is like it is in limp mode. How can I reset that?

Can it be the computer on the side of the block?

Would it be in need of a re-flash on the computer?

Hell, I am at a loss here?????

 

My truck did something like that when the MAP sensor went bad.

 

Do you have 0 to 10% or just 10%? Have you checked wiring to the ECM and APP sensor. Did you try calibrating the APP sensor? Any other issues codes or gauges reading incorrectly? oh by the way what year truck our we talking about?

 

That's what came to my mind too. It would be nice to have a scanner and a manual boost gauge, and verify what the ECM is seeing for boost. I would also pressure up the system with my boost leak tester, verify no big leaks, then see if the MAP sensor could read that.

I had a 98.5 truck last year that blew out a metal plug from the bottom of the preheater, directly under where the wires attach to the studs. Created a big sudden boost leak and power loss. Working with these trucks for years, and that was the only time I've ever seen that. Just one more thing to check.

 

the blown plug from the heater happend to me. check that map sensor mine did that once, replaced it and problem was gone

 

hmmm...i can only guess at this but im thinkin this is a trans-ecm communication problem,i would think if it were ecm, injector pump, apps, related it should do the limp mode thing in neutral also, i asked about the wiring harness because i have seen wore through wires cause no communication between pump an ecm, [usually sets a code to] truck goes limp mode but does it in neutral also.

 

1998.5 is the year. I will try the MAP sensor. Is there a way to test it? I don't get why it wont set a code. Every once in a while, it wil take off and run like it supposed to, but lately it will only get just off idle for power.

The 0-10% comes on smooth, when it comes off idle, it seems to flatten out and not do anything else. I have checked the wiring and plug ins everywhere and they seem to be good.

I am pulling my hair out here.

Thanks for all the suggestions,

Jeff

 

You know how a computer needs re-booting every now and then...you might try disconnecting both batteries for an hour or so to reboot your truck computer.