in trying to diagnose the loss of power problems i'm having (~3 posts down in https://www.ford-trucks.com/forums/1...-to-pedal.html), I found that the EBPV valve was not unplugged as the PO said it was.

I just unplugged it an lunch and found that the engine harness side of the connector was in pretty bad shape - still seemed to make connection, but insulation was missing from one of the wires going into the plug. I thought for a bit that this could be my problem, but looking at the engine wiring diagram, it looks like the valve is controlled by the PCM supplying voltage rather than supplying GND - i.e. shorting that wire to ground would not actuate the EBPV.

however, it still could be that the EBPV valve was actuating when it shouldn't have been, causing the low-boost power-loss that I've seen.

then, the question becomes why? unplugging it should solve the issue (if this was indeed the cause), but could it be a bad EBP sensor, intake air sensor or bad BARO sensor? do these sensors also feed into the PCM figuring how to fuel the engine?

finally - now that the EBPV is unplugged, I assume that the internal spring will hold it open. I tried actuating it by hand and could move it somewhat, but it always reverted to the starting position - i'm assuming that's "OPEN" or another way - does the actuator shaft extend or shorten when closing the valve?

thanks!

 

This may not help, but I remember a thread a while back where someone tracked their issues to the sensor in the stock airbox - I can't remember which one it is. It's not the MAP i don't think. It was strange because everyone dismissed that sensor and he found it was a problem for him. Just a thought...

 

Dan - interesting - the Intake Air Sensor - I noticed that the one on this truck is missing its dust cover (or whatever is over the tip of it) and is quite dirty, so I wouldn't be surprised if that this is getting funny readings. I also thought that it really didn't do anything other than tell the PCM when to turn on the fuel bowl heater and a few other non-essential items. but if that does play a role somewhere, it is worth a look-at. I could pretty easily swap over the one from my other truck that has never given me problems.

I think my scanguage has an option to monitor intake air temp - i'll have to check that out next time it acts up - I don't think the reading in my other truck has ever made sense - like its not actually reading, but just putting out a steady value or something...

I am definitely thinking that it is some sort of sensor issue here, though, as the engine sounds perfectly fine when its losing power - not like its missing or anything, and the ICP and IPR numbers are fine as well. its really just like the PCM is telling it to go slow, for some reason.

 

I must have a PCM issue in my brain like that!!!!

 

What does the oil temp sensor reas on your scan gauge. Thats how the PCM decides it needs to close the EBPV, IIRC. But it should open up when you are trying to drive. I'm not sure if its throttle position, rpm or EBPS, but at some point it should open up.

When mine was on the fritz, I just unplugged it. Once it got warm and I felt like working on the truck, I just gutted it and never looked back. What was interesting on my truck was that the valve never opened all the way. When it was supposed to be open it was still turned about 15°. So I noticed a bit more power after I gutted it... and it sounds awesome.

 

Well I just gutted the EBPV on my new truck, and put my air intake on!

 

yep - that's definitely on my list of things to do, but i just settled for wiring the EBPV open this weekend rather than tearing into it right now. i'm hoping to do some sort of upgraded/hybrid turbo using a SD turbo i have on the shelf, so i'll tackle the EPBV delete at that point.

the engine lift point made a handy anchor to wire the valve to, though.

of course, this low power problem hasn't occurred in the past few drives, so if it never comes back, i may never know if it was my cruddy fuel filter and screen, or the EPBV. if it does come back, i'll know its neither one and keep plugging away, though :-)