Randomly my truck will seem like it’s misfiring or has a vacuum leak. can find any vacuum leaks, new air filter, new coil since it tested out of spec. The rest of the time it runs great.

Pulled the codes from the CEL self check with engine off. Got a 335 code. I tested my Egr valve with a vacuum pump to make sure it’s not stuck, it seems to be operating.
I’m looking for the testing procedures on the ebpv sensor before I go throwing parts at it...

Thanks!

 

Not sure what an "ebpv sensor" is?

DPFE was the common name for the EGR pressure sensor
It has 2 hoses that run to the EGR pipe, one hose is closer to EGR the other farther away, obviously there is an order on where they hook up on the DPFE

As computer opens EGR valve the DPFE tells computer the pressure difference between the two hoses so computer can tell how much exhaust is being add to intake air
Because exhaust gases are also full of water vapor the DPFE hoses can get water condensed inside, and when engine is off the DPFE chamber also gets moisture inside, so not at all uncommon for these to fail after 5 years or so
Try to keep the hoses at a downhill angle with no dips so any moisture runs out and into EGR pipe after engine is shutdown

EGR system is not used when engine is cold
And then is only used when accelerating or cruising
Point of EGR is to lower cylinder temps to reduce NOX emissions which spike when cylinder temps get hotter, i.e. when engine is under load

Good read here on Ford EGR system: http://www.tomco-inc.com/Tech_Tips/ttt36.pdf

As for rough idle
Try a can of Seafoam or similar injector cleaner in gas tank, I need to do this once a year on my 1994 4.0l to smooth out idle
Dirty fuel injector tips tend to DRIP fuel at low demand(idle), vs spraying fuel so it makes for a poor air/fuel mix and misfires

After engine is full warmed up and idling, unplug the 2 wire connector on IAC Valve, it will then close
Engine RPMs should drop to 500, or engine will stall, either is good it means no vacuum leaks
If idle doesn't change then there is an air leak

Also just as a heads up, 1993 computer will need the 3 capacitors changed, not hard to do and under $5
Had to do my 1994 a few years ago
Seen here, the 3 blue cylinders: http://www.auto-diagnostics.info/ford_eec_iv
These will cause odd running issues as they fail/leak, not your current symptom I don't think

 

I meant the DPFE, I’ve heard it called the exhaust back pressure sensor before.


I’ve already ran Marvels Mystery Oil through the g

as, definitely helped smooth it out, especially on a cold start.

My guess in the DPFE is bad, the old one had a short or something and roasted the pigtail. So I got a used sensor and connector from the yard and repaired the wiring but couldn’t find a testing method on testing the DPFE itself.

Thanks for the heads up on the capacitors! 🙏🏼