Good morning. I'm "new" to the forum in that this is my first post, but I have been using the insight on here for some time as I work on things on my son's 1997 F-250 PSD. We have a new problem that just recently started. Some times the tubo will not spool, and when that happens there is much less power. Not less power in the sense that the truck is missing the power boost from the turbo, but less power in the sense that it just will not get rpms/speed up.

The truck is more or less stock, except we did the 6637 air filter modification, the fuel tank hutch and harpoon mods, removed the fuel bowl heater element because the connecting points inside the fuel bowl, and the FPR shim due to low fuel pressure. This power/turbo issue just started and not in relation to the timing of any of these modifications (except the front tank hutch mod).

We took the intake hose off and could easily turn the fan on the intake side of the turbo. Did not check for wobble, but fan spins freely best I can tell. The truck doesn't have any aftermarket gauges, so I cannot tell you about boost, etc. Only that you can tell when the turbo won't spool because of the way the truck is running. This has happened from start-up and has happened while running (i.e. ran normal then loss of power/no spooling. When it happens it is often fixed by shutting the engine off and restarting.

Your help in diagnosing this is very much appreciated. Or direction to a prior thread is fine as well. I've been searching but cannot find anything similar.

Update:
1) Sorry, I didn't first notice the sticky that this is an introduction only forum. I will try to figure out how to transfer.
2) Truck has 285k miles, manual transmission.

to the nation. Just repost to the right section. And you should be able to modify this post for a short time more.

If it runs fine first, then out of nowhere, mid-drive, it starts to feel like a lack of power. Its most likely not a turbo. If restarting the truck fixes it, its not turbo related.

Lt.Dan, thanks for the reply. That knowledge will at least help narrow down the list of possible issues. For clarification, sometimes it has reduced power at start-up with no spooling, and sometimes it if just fine at start-up. There has been at least once it did not have power at start-up but after couple miles things kicked in. Other times it ran fine and then loss of power. And yes, so far a restart seems to always correct the issue.

If not the turbo, then could this be a fuel pump /fuel supply issue, or do these symptoms indicate a likely suspect as one of the several sensors, etc. that I am only beginning to figure out what they do or don't do?

Thanks again.

EBPV sticking?

That would be my next guess ^ check to ensure it is either functioning properly, or disconnect it.

Thanks for those thoughts. I think I can test that by unhooking the wiring harness at the pedestal and run for a while to see if the problem stops?

Would a sticking EBPV be the culprit even if the loss of power happens mid-drive? I thought the EBPV was to close during cold temperatures to help the engine warm at start-up. Does it open/close more frequently for some reason or another by design, or could it be the sensor that is malfunctioning?

Either way I guess unhooking it will let me know if that is the issue. I'll update when I know more.

Thanks

Mine started malfunctioning for no reason while driving on the freeway and warm, it happens. Mostly its because the EBP sensor and tube is plugged with soot.

Unhook it at the coupler right underneath the butterfly and see if it moves by hand freely. Then wire it open to see what happens.