OK.

97 F350 7.3 liter.

When the oil temp is below 140*F the truck is falling on it's face. I've parsed through 4 AE datalog files looking through this...

Original EVP sensor is working, but the voltages are reading just a little bit high in all ranges... but not high enough to throw a code. For instance RPM's in operating range, it will wander to about 3.3 volts, where the range should be 0.8 to 3.0... but the PCM doesn't throw a code for out of range until 4.6v plus...

So I'm trying to understand that...

There's the system itself, which when cold (Engine Oil Temp below 140*F), closes the EBP Valve. In the pedestal, there is the EBP Regulator, which "regulates" (or actuates) the closure of the EBP Valve. The EBP Sensor, senses the current EBP in PSI and feeds a signal back to the PCM. (Not sure what the PCM does, or is supposed to do with this variable voltage signal from there!!!)

Supposedly, the system is only in effect with EOT below 140*F, right? So...

- How does that system work in detail? If it were just to close the EBP Valve when it's cold, then it wouldn't need a sensor, it would just go off of temperature alone, right?

- Is the EBP Valve just full open or full closed, or is there supposed to be points in between? If only full closed or full open, then it wouldn't need a EBP Regulator, right?

- Does the sense voltages returned from from the EBP sensor hit the fuel tables? Meaning, what does the PCM do with the variable voltage signal?

Just trying to figure out what is going on with this... If I let it get cold and drive it (after only a few warm up), it sucks until about 15 miles down the road (after it hits EOT above 140*F)... But below 140*F- Nurse it up to 55mph. Go to WOT and it will lose speed!!!

I ordered an EBPS, thinking... But something is nagging me with this. People tell me this should NOT run this bad. But if I disconnect the EBP valve (only change) while the EOT is between 80-90*F... this things runs like it's on steroids.

 

Ebp sensor works off oil temp only.....with that being said, unless you are in a cold enviroment all the time, if you unplug the epv at the base of the turbo. Two wire plug going to the turbo base, it will defualt open and not close in any condition. This is okay unless you are in sub zero temps a lot and need truck to warm up faster.

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Then why is the EBPS labeled as a "variable capacitance sensor?" If it was just on/full closed and off/full open, then there would be no need for the sensor at all... right? It would just be the EOT (alone) and no EBPS at all.

I live in the Pacific Northwest. I sometimes see -20*F... but most of the time in the winter, it's the +20-30's (F)... Right now, I cut the wire and have it run to a switch. Other's say you don't need it if you have it chipped and have a "High-Idle Tune" in the mix...

Well mine (stock tune) has no high idle anyways... But I do have an ACIM Controller that I use for High Idle.

Why do I have it on a switch and not unplugged? Because I have the EBPR wired into another switch with relays in an Exhaust brake/Trans Lock circuit...

Other's say if the tube for that EBP sensor is plugged... you use more fuel. So there must be some relationship from the Exhaust Back Pressure to the fuel tables... Does that make sense? And if you unplug the sensor and don't plug in a sensor bypass (which just sets the sense voltage to the median, about 1.25v)... that end of the circuit, just unplugged, it will throw a DTC.

 

I replaced the EBP sensor. It was working, sort of. From Ford's specs, it was within range in that is was "in" enough to not throw a code. But by Ford's other testing spec's it was reading a little high in all the test ranges.... So I replaced it anyways. There was no change in what it is doing at all!

I did more research. Seems that there are 2 more sensors that affect that system. Looking through Ford's manual's, the IAT and the Accelerator Position Sensor both say they supply data to the EBP system. Those sensor's on mine, seem to be working fine. In that manual, it also said that the EBP system should get bypassed and the EBP Valve is supposed to open under a high load or high rpm condition... which mine doesn't (isn't doing)--> But it gives no path to follow in their decision tree if that "doesn't" happen.

I thought I had exhausted all, but I guess not. I need ideas now.

 

Could be a bad valve in the pedistal. The valve that opens the exhaust butterfly is a hydraulic valve. If the valve is stuck it would keep it from opening. Bad news is you would have to remove turbo and pedistal to do anything with that.

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The hydraulics work. Normal is open. Closed is from a signal from the the PCM to the EBP regulator... which is an electric/hydraulic switch that lets oil into the EBP actuator, that has linkage that closed the EBP valve.

No power, then the oil in drains out of that port, the piston gets pulled back by it's spring and the linkage opens the EBP Valve. So in all practicality, the piston closes the valve...

So... Yes, it physically works, but working logically correct. It's confused.

If the Intake Air Temp Sensor says it's less than 46F and the Engine Oil Temp Sensor is less than 140F... Then the logic says it's cols and needs to warm up faster. So it closes the EPB Valve. It should be that way (if it is low load and low RPM) unitl the EOT gets to 140F. The EBP Sensor measures EBP pressure, which should not get over 38 psi. Also tied in is the Accelerator Position sensor... Because somewhere, the logic is supposed to say in a high load (over 38 psi)/high RPM (over 2500 RPM) and still below 140F EOT... Temporarily open the EBP Valve.

That last part is where mine is not working right. I could just unplug the EBPR... but that isn't the point. It's not working right.