The truck idles fine but as soon as you go to give it some acceleration it will cut off. We have replaced fuel filter and pump and it still does the same thing. Sometimes it will kind of buck and when it does white smoke comes out the exhaust....normally there's no smoke. Any advice is welcome...Thank you

 

I have a '97 also...

- How long have you had the truck? (Is this your first winter with it?)
- What is the ambient temperature outside overnight? (Does it have a block heater?)
- What is the engine oil temp when it's doing this?
* Check to see if the Exhaust Back Pressure Valve is open or closed? Open will be with the lever towards the turbo pedestal... Or with it running, pull the EVP regulator electrical plug (right side of turbo pedestal) and see if it opens or just stays still...

Once upon a time, my own truck, after I bought it... the EVP regulator to valve linkage had come apart and the valve had stuck closed.

If it is moving, but is still falling on it's face... Look here for the specs.. Check it and see if it is in range with the sense voltages it is passing. You should use a scan gauge where you can monitor Engine oil temp, as that circuit is only in effect when the EOT is below 140*F. If you go back to the exhaust outlets, they will have a distinctive hissing sound when this valve is closed.

Having said the "worst"... The OBS PSD's will "normally" be sluggish and smoke a little when it is cold outside and the engine has not warmed up yet. That is normal. But they should not fall completely on their face. when cold.

 

I had this truck for a 1year and a half now this second winter up here in North Carolina it started acting funny 2 or3 mths ago and now its gotten worse to where it would shut down at a red light and do it 2 or 3 times and run good as far as oil temp it has a stock meter which it stays in the middle or meter

 

So the "stock" oil gauge reads oil pressure, not oil temp.

Did you check the other things I asked? (You did not answer those...)

 

I DIDN'T SEE EVP VALVE I NOTICED THAT WHEN I LET OFF GAS IT ACTS LIKE IT HAS A MOTOR BRAKE ON IT

 

Look at the turbo from over the grill, looking to the firewall. As you look from that perspective, on the right side, the exhaust side of the turbo, you will see a 2" wide casting on it, right before the clamp to the exhaust downpipe. It has a freeze plug on the top side... and a shaft with a lever on it coming out of the bottom.

That is the exhaust back pressure valve. Below 140*F of the engine oil temp, tha valve closes... Causing a the exhaust to close off. This is supposed to close like that so the engine will warm up faster.

If you look at that for the linkage that connects to it, follw it back under the turbo to the aluminum base that the turbo bolts to. That is the turbo pedestal. Where than linkage goes into the pestal is the Exhaust Back pressure regulator. On th opposite side of the pedestal, near the inside edge of the valve cover is the plug for that regulator. That regulator, opens and closes the Exhaust Back pressure valve.

Under the black cowl that covers the fuel filter, on the back of the HPOP reservoir, on the passenger side, is a sensor with 3 wires. It is the Exhaust Back Pressure Sensor. Under that is a tube the goes down to the front of the passenger exhaust manifold. This part of the system measures exhaust back pressure in PSI and sends that info back to the PCM via a sense voltage.

I just spent 3 days with 3 different Ford Diesel Tech's. They say they were not taught what that sense voltage does. But from what I can figure out... that info tells the PCM to hit the fuel tables and adjust the fuel based on the PSI of the Exhaust Back Pressure...If there is a problem with wrong info being sent... then wither the tube is plugged, or the sensor is sending wrong info back (bad sensor).

SO-- Before you start the pickup, look at the EBPV (Exhaust Back Pressure Valve). See if it is closed (lever away from the turbo).

Start the pickup cold. EBPV should close.

Let it wram up for 3-5 minutes. Is it still closed (when cold it will take longer than that to open)... Drive. It will be sluggish.

Pull over. Pop hood and unplug the EBPR plug. Drive. See if it clears up.

Plug back in. Let the pickup warm up fully. When fully warm, the EBPV should be fully open. If it doesn't. test the EOT (Engine Oil Temperature) Sensor.

If it only runs bad while the EBPV is closed, make sure that EBPS tube is clear, open, not-clogged. Test the EBPS (Exhaust Back Pressure Sensor).

Is that enough of an explanation and enough info for you to understand what to check?

If it runs good with the EBPV unplugged, there's no harm / no foul... to run it like that until you figure out what is wrong. Some people delete that valve and the regulator altogether. Just make sure you warm up the motor a bit before you take off.

Me? I run a switch to turn that circuit off while cold. The when warmed up, I flip that switch back... because I use that same valve wired into relays in a translock... as an exhaust brake... which like you mentioned, with that valve closed, it's like putting on the brakes.

Please post back the results of your exploration.

 

I disconnected the EBPV and it doesn't stall out thanks for the info going to take it for a ride today and see what happens

 

OK/Good.... Next tests would be with a Volt Ohm Meter (VOM). Tell me if and when you're ready for that info.

 

Well I got in it yesterday and started it up and let warm up for 15 mins and did same thing died 4 times

 

With it plugged in right? I'm interested in this personally, as mine is quirky about this and even though I've bypassed and worked around the problem on mine... I'm the kind of guy that isn't satisfied until I fully understand what's going on. I'm known for my skill in diagnostics... and this problem has become a challenge to me personally.

Well, from all the manuals I've read on this, Ford isn't straight forward in how this system works and what is involved in it. I've talked to 2 Ford trained diesel techs and 3 different Ford Service Managers, at 3 different Ford dealerships... and they tell me that Ford doesn't tell tell "how" that system works or the mapping of the PCM. They just thought the EBP system invloved the EOT, the EBPS, EBPR and the EBPV. I didn't take Ford's explanation as the whole truth, because depending on what document of their's you read, they say different things.

In other Ford Doc's I've read, It's a conspiracy...
- The IAT (Intake Air Temp) sensor... The PCM uses the air temperature information to operate the Exhaust Back Pressure (EBP) system.
- Accelerator Position (AP) input is used by the PCM to control the exhaust back-pressure regulator.
- The Engine Oil Temperature signal is used by the PCM to calculate fuel quantity, injection timing, glow plug operation and exhaust back-pressure.
- And the EBPS...
Notice that the threshold/decision tree temps listed in their docs seem to change. I'm thinking that those decision points may have changed in later flash images. Mine is at 140*F of EOT... That also says (highlighted in red) that there is supposed to be some logic and control there in the PCM to over-ride that system under load.

So from different sources, I found these to check the EBPS (my notes):
So from personal experience, here is what was going on with mine and why I bypassed mine. I had mine looked at by the Ford dealer. Big mistake. They lied to me and lost my confidence. Long story short, what I found was that the EBPV linkage was disconnected and was froze shut. Not telling how long the linkage disconnected. I just hadn't noticed that before. Previous to me, the truck was commercial... and some the the things they did... so it might have been for a awhile... or it might have been on it's own over time... But I suspect it had a problem, and they never tracked it down to just what it was.

I rounded up the usual suspects. I tested the EBPS and it was a little out-of-range, but not enough to be totally gone enough to throw a code. While I was testing it, the tube going from the right exhaust manifold, to it was plugged. I cleaned it out and unplugged it. I replaced the sensor, thinking maybe because it was a little out of calibration... but those were not the my whole of my problem.

Anyways, that lead me to wonder if someone did disconnect the linkage on mine, the "WHY" of why someone might have disconnected the linkage on my EBPR...
Notice that highlighted in green, restates what it said before, but sort of ties it more together. The red, just comes out plain and says there should be an override, that is should not be on during high load and high speed conditions... Which is the problem mine has... and your's.

My EBP regulator and solenoid work, to a point... The solenoid works, it that if you have it unplugged in when you start it (my breakout switch off), the system works great, no problems. If you start it with the the system as normal... the valve is closed and there are problems. If I start is with it open and close it with the switch, that works. But...

If I start it with the switch closed and open it, the valve remains closed... until I turn off the motor and restart it. There in lies "MY" problem, with "MINE."

I figure with mine, actuated regulator seems to mechanically work. So, with mine, it could be the EBP valve sticking (while there is back pressure against it), or it could be that with mine, there may be some quirky sticking (or intermittant leaking/pressure bypass condition) of my EBP solenoid.

Your's? I don't know. Someone really needs to check components in "YOUR" system to track down yours. I am not there, so that leaves you... or whoever you pass that on to. If that be you, then ask questions on "what" you what to test, to rule out. I've been on that adventure. Hopefully I'm on the downhill side of mine for that. I'm not all-knowing, but I've had to learn to try to figure out my own problems. And my own problems were out-of-the norm of vehicles that I had to repair or service for others. (Funny how that happened!!!) I haven't come to the end of my adventure yet on mine, but I've got a lot of things ruled out... I could just disconnect it and say good enough... but I want it to be able to open and close at will, on demand... so I can use it in a custom exhaust brake mod. I need it to be able to open and close without having to turn off my motor, to be able to do that...

What is also of note... Is that other Ford documents, if I look at commercial vehicle versions of this motor, it lists the EBPS as "optional."

Just saying...