CP3 defueling how does it work?

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clarkoh

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Trying to better understand defueling and/or limp mode. How does the ECM control the CP3 pump to cause defueling?
I got my 2004.5 common rail installed in my Excursion. When I attempt to drive it, the slightest actuation of the throttle ends up with big time surge or stalling. Watched the rail pressures on Auto Engenuity. I see about 5-7000 psi at idle 750rpm. As soon as I raise the throttle, the pressure starts to rise then cuts way back, occasionally I see a zero. When I lift, if the engine hasn't stalled, the pressure responds and gets up to 15-16,000psi. This lasts about 4-5 seconds and then drops back to 5-7000 as the engine gets back to idle.
One thing, the ECM was reflashed from 6 speed to automatic. I decided to go with an Anteater, eliminating the need for automatic control/ monitoring. Hence, there are no connections between the ECM and the automatic. Could the ECM in the confusion be defueling the engine to protect the transmission? The ECM is back with the programmer getting the stick program reinstalled. Update pending, hopefully by the end of the week.

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Got the ECM back. Now flashed as a stick. Still will not take any throttle. Rail pressure drops, until throttle is released. Even the slighest throttle position, like 30% results in big stumble or stall. Lots of smoke, some white, some black. Codes are p1652, p0517, p0628 and p0622 which has a list of engine parameters,. Any suggestions??

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Rail pressure. Was asking if auto engenuity can show command vs actual.


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I am getting a good Cp3 pump tonight, on a loan. At least I can swap it and other spend more money.

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What transmission was the ECM originally flashed to?

Which engine harness are you running, Auto with APPS on the head, or Manual with the APPS under the battery tray?

CMIIW, but I believe the 2004 or 2004.5 ECM pinouts for the APPS are set according to the original flash and re-flashing won't change them.

Mark.
 
Last edited:
Mark Nixon said:
What transmission was the ECM originally flashed to?

Which engine harness are you running, Auto with APPS on the head, or Manual with the APPS under the battery tray?

CMIIW, but I believe the 2004 or 2004.5 ECM pinouts for the APPS are set according to the original flash and re-flashing won't change them.

Mark.
Click to expand...
It was a 6 speed. When the reflash to eliminate VIN was done, the ECM was changed for automatic. I'm using a 48RE with an Anteater. Hence, the change back to manual.

The harness came from DCS for the rear most connector for the ECM. I could not recover the original. The APPS came from an automatic 2005 truck. It is on the throttle pedal. I got the connector with the pedal. DCS built the harness using those parts.

Is there some input from the stick shift truck that might not be getting to the ECM which could result in defueling??

One other issue. I tried to use the high pressure lift pump from the Excursion at first. I have since switched to an Air Dog with 18psi. Could the excessive inlet pressure have damaged the CP3??

Tomorrow, I am going to swap the CP3 for a known good one. Before doing that, I am going to swap the fuel pressure metering unit. Just to eliminate any issue with it. Plus it's simpler then changing the pump.

Thanks for the help.


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clarkoh said:
I am getting a good Cp3 pump tonight, on a loan. At least I can swap it and other spend more money.

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Click to expand...
Edit: Before spending more money!

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pick up an extra fca and rp sensor, always good to have in the tool box to rule out stupid little things like those
 
clarkoh said:
I am able to monitor RP through auto engenuity. Not sure how to command it?

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Click to expand...

He is asking if you can monitor what it is commanding to be put out and what it is actually putting out. With other scanners you can actully see this. They should stay close to each other.
 
Changed out the fuel pressure unit on the pump. No change. if I give it more than 10% throttle, it stumbles, rail pressure drops and engine stalls unless I am quick it let the throttle go back to zero/ idle. Its snowing, I am going to go home, while I still can. This North Carolina, 1/2" of snow mungs up everything. Stores are already out of milk and bread! LOL

And thanks to all for the help. Gonna figure this out!

?? I am thinking maybe the 2004.5 donor had a TPS mounted under the battery box?? It was stick. Might see if I can locate one and see if it likes that style TPS, rather than the APPS on the pedal?
 
Last edited:
clarkoh said:
Changed out the fuel pressure unit on the pump. No change. if I give it more than 10% throttle, it stumbles, rail pressure drops and engine stalls unless I am quick it let the throttle go back to zero/ idle. Its snowing, I am going to go home, while I still can. This North Carolina, 1/2" of snow mungs up everything. Stores are already out of milk and bread! LOL

And thanks to all for the help. Gonna figure this out!

?? I am thinking maybe the 2004.5 donor had a TPS mounted under the battery box?? It was stick. Might see if I can locate one and see if it likes that style TPS, rather than the APPS on the pedal?
Click to expand...
Another thing I saw. Throttle percent went above 99% when floored. Auto engenuity display turned red. This was with key on, not running. I am suspicious of the APPS. And /or wiring. Can anyone tell me what voltages should be seen at the connector full and no throttle?

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Mark Nixon said:
What transmission was the ECM originally flashed to?

Which engine harness are you running, Auto with APPS on the head, or Manual with the APPS under the battery tray?

CMIIW, but I believe the 2004 or 2004.5 ECM pinouts for the APPS are set according to the original flash and re-flashing won't change them.

Mark.
Click to expand...
6 speed,,

custom harness built by DCS using 50 pin connector harness plus excursion harness

got the gas pedal APPS from a later 06? Truck. I am going to try to find the TPS from under the battery box.

Thanks.

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