loss of power

[billy1971]

ok i have a 96 c3500 6.5 td with a remote pmd if you accelerate kinda heavy at 70 mph it loses power or if you get on the interstate and run 70 mph for about 6 miles it will lose power i can pull over and shut it down for a few minutes and the power will come back i have changed the injector pump, fuel pump (with a a/c delco) filter, sock in the tank with no change it will throw a iat sensor high code but only sometimes. i have run a tech II on it nothing stuck out irregular changed pmd , iat sensor, map sensor nothing changes it does have piston noise and i intend on changing the engine out but i wanted to fix the drivabilty problem first i do feel this is a electrical problem of some sort as the only way power will come back is to shut it off i am at a loss any ideas would help i have had diesel for several years and have never encountered anything like this truck is stock other than remote pmd also not real handy with this typing but once the truck losses power it does not come back till you shut it down for a few minutes letting it idle does not help i have noticed that outside temp has something to do with it possibly

[sctrailrider]

Sounds a little like it is starving for fuel, do the fuel cap check, and check to see that the LP is working, might be pulling a vacuum and keeping it from getting enough fuel. Try the fuel cap loose and see if it still does it, this would be a good start. When you changed filters, did you clean the small screen out??

[billy1971]

yes i tried runnining without fuel cap no change however i did not know of a screen in the filter ? i run a fuel pressure gauge on it its about 4.5 psi at idle and2.5 fullthrottle

[sctrailrider]

What does the gauge do when it starts to loose power??

I could be wrong, and the pros will chime in, but I think there is a screen both in the FFM housing & in the pump inlet... might check them.

[Robyn]

The IAT code may be the key.

Shutting it off resets the computer.
My gut feeling is that you are seeing a possible overboost condition that causing the computer to drop things into LIMP mode.

Have you checked the wastegate controler to be sure its working.

Get a boost gauge on the thing and see whats going on there.

With good power the boost should not exceed about 8 PSI maybe 10 for a short time and if it goes above this and stays there the ECM will set limp mode.


The fact that shutting it off and then restarting makes me suspicious of the limp mode being set.

High intake air temps can be caused by onloy a few things, mostly too much boost.

Does this truck have the Cat still in the exhaust ??

If it does it could be plugged. This will cause too much back pressure and result in issues.

Keep us posted

Missy

[billy1971]

ok cool thanks it has set a wastegate circuit code and yes the cat is cutoff thanks alot yall i will order a boost gauge and go from there thanks:D

[billy1971]

ok i am back put a boost gauge on 10 psi max never looses that i had another good 6.5 so i dropped it in still having same problem but i did put the scanner on it and found the tdco is off tried to adjust and i am getting bad numbers other words if i do a tdc relearn it will be differant each time without moving the ip so my question is what gives this info on the truck i kinda beleive i have faulty wiring now since everything else has been touched thanks Billy PS the exhaust is straight minus a 3inch glass pack