i have a 96 f450 powerstroke with a serious loss of power.60 mph is top speed pedal to the floor.dosent seem be missing at idle or drive.it smokes white on startup but i realize ive got some bad glow plugs.fuel filter has been replaced.could it be a bad turbo or cylinder compression loss?

 

It's not blowing any smoke while your full throttle??? Look at where the intake tube goes into the turbo, under that towards the bottom of the turbo there is a little 2 wire connector there. Unplug that and see if that fixes your problem. That plug is for the exhaust backpressure valve. Sometimes they will shut and cause a very low power situation. It will open if you unplug it.

 

No smoke at full throttle

 

Check your fuel pressure at the schraded (spel?) valve and clean your FPR screen.

 

55 at the shrader idle and wot

 

OK, so did you unplug that backpressure valve yet? You can check the turbo condition by removing the intake tube, grab the center of the compressor wheel, and see how much play it has up and down and in and out. It will normally have a little bit of up and down play, but shouldn't have any in and out play.

 

Maybe you need to shim it.

And did you clean the FPR screen yet?

 

55 psi is fine for now. If you decide later you would like to run the correct fuel pressure, you can shim it later. For now, 55psi is ok and shouldn't hinder performance much if any.

 

I haven't tried the plug by the intake tube yet.or check for any endplay in the turbo.will check that after work.the fpr screen is clean.I hear the turbo spooling up in 2nd gear if that means anything.

 

I'd unplug the backpressure valve before concidering anything else. If it still does it after that I would start looking at possible high pressure oil problems or severe boost leaks.

 

being a 450 was it a fleet truck? There was a guy on another forum who bought a fleet truck which was chipped so that it had a maximum speed. Might want to check that... Not saying thats the case, but its something to rule out.

 

Now thats thinking outside the box James. Good idea on the chip w/ a speed limiter. That never crossed my mind.

 

No speed limiter.anyway I have a 94 powerstroke.I was thinking of another truck when I posted as a 96.I don't think it was possible to chip those?

 

I've not found a backpressure sensor by the intake tube.but I found a butterfly valve on the backside of the turbo that has been tied/open

 

ok folks i have checked my turbo endplay.it dosent move at all in any direction,so i assume the turbo is ok.i hsvent found a connection for the backpressure valve.i did find a butterfly valve on the exhaust side of the turbo that had been tied open.i double checked the shrader valve pressure and found it to be 60 psi idle and wot everything seems fine there.i changed the fuel filter again and cleaned out the canister.where is the screen located everybody is talking about?