Originally Posted by ps54888
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...
Exhaust Back-Pressure Sensor
The Exhaust Back-Pressure sensor is a variable capacitor sensor that is supplied a 5-volt reference signal by the PCM and returns a linear analog voltage signal that indicates pressure. The Exhaust Back-Pressure sensor
measures the pressure in the RH exhaust manifold. This sensor is used in conjunction with the exhaust back-pressure regulator to form a closed loop exhaust back-pressure control system.
The exhaust back-pressure is controlled by the PCM to provide more heat to the coolant for cab heating when ambient air temperature is below 7 C (45 F) and engine oil temperature is below 75 C (167F) during low load,
low speed operating conditions.
An open or short in the Exhaust Back-Pressure sensor wiring will result in a low out of range voltage at the PCM,
and the PCM will disable Exhaust Back-Pressure control.
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):
The voltages the EVP Sensor should have is:
Key Off- 0v
Key On- .8v-.95v
High Idle- 1.25v-1.75v
Operating Range- .8v-3v
While circuit is active- Voltages below 0.25v and above 4.6v should throw a code...
:: Re: fordtechsdervice- 1997 PCED On Board Diagnostics II Diesel, Section 6C, reference values, pin 30, EBP, Circuit #553. :: Note- for Op. Range values, Ford's Manual actually has a misprint and has it listed as 0.8v-0.3v, where is should be 3.0v...
At all conditions, I am getting too high of voltages fed from the sensor back to the PCM. So the EBP Sensor is working, but there is not enough resistance to it... so it is bad. I ordered a new EBPS. It is on it's way.
I also found these specs, which were similar, but a little differing:
After removing connector always check for damaged pins, corrosion, loose terminals, etc.
Connector Checks to Ground (B-)
(Check with Sensor Connector Disconnected and Ignition key off, all accessories off)
Test Points Spec. Comments
A to Grd. < 5 ohms Resistance to chassis grd. check w/key off, if > than 5 ohms harness is open -Signal Grd.
B to Grd. > 1000 ohms Resistance less than 1000 ohms indicates a short to ground. - VRef
C to Grd. > 1000 ohms Resistance less than 1000 ohms indicates a short to ground. - EBP signal
Connector Voltage Checks
(Check with sensor Connector Disconnected and Ignition Key On)
Test Points Spec. Comments
A to Grd. 0 - .25 volts If greater than .25 v signal ground is open or shorted to VRef or battery.
B to Grd. 5 ± .5 volts VRef check with key "ON," if voltage not in spec., see VRef circuit
C to Grd. 0 - .25 volts If greater than 0.25 volts, signal wire is shorted to VRef or battery.
Harness Resistance Checks
(Check with breakout box installed on engine harness only)
Test Points Spec. Comments
#91 to A < 5 ohms Resistance from sensor connector to 104 pin connector - Signal ground
#90 to B < 5 ohms Resistance from sensor connector to 104 pin connector - VRef
#30 to C < 5 ohms Resistance from sensor connector to 104 pin connector - EBP signal
Test Points Operational Voltage Checks
(+) #30 to (-) #91 (Check with breakout box installed in line with the PCM)
Voltage PSI KPAG Comments
.8-1.0 v 0 o Signal with key "ON" and engine OFF (Value dependent upon atmospheric pressure and altitude.)
.8-1.0 v 0 0 Normal warm idle signal.
1.19 v 14.8 10.0 Minimum signal expected at 2300 RPM with warm engine. (See EPR diagnostics)
Circuit Faults: Diagnostic Trouble Code Description
0472 = Signal voltage was less than .039 volts for more than 0.2 seconds.
0473 = Signal voltage was greater than 4.90 volts for more than 0.2 seconds.
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...
Exhaust Back Pressure Regulator
The exhaust back pressure is controlled to provide more heat to the coolant for cab heating when ambient air temperature is below 5C (40 F) and engine oil temperature is between -10C (15F) and 83 C (182F) during low load, low speed operating conditions. At high load, high speed conditions, the back pressure system is disabled.
The exhaust back pressure regulator solenoid and exhaust back pressure piston are contained in the turbocharger mounting pedestal. Turbocharger pressurized lube oil is routed to the exhaust back pressure solenoid. Oil regulated by the exhaust back pressure solenoid actuates the piston which operates the back pressure valve in the exhaust housing.
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."