Engine Code P0451 problems

[Bunsin]

It's been a long ride, but at this point I'm getting close to the end of my rope...

I have a CEL with a P0451 code that I can not figure out where it is coming from and no amount of searching for this specific to our cars is yielding results. I just got done replacing the evap canister and canister pump module (yes getting those out is a pain even after dropping the dif) and I am still getting this damn error (shows up after 2 starts). Odd thing is it is the only error I get (i.e. no large of small leak errors). However, as the car drives it causes issues with running due to what I assume the learning part of the ECM and the interplay with the evap solenoid. Clearing the error even when the evap solenoid is deleted from the 'circuit' changes the engine RPM so it is still effecting the learned part of the tune regardless (went into limp mode on one trip when the evap solenoid was in and tank was full). Given there are no leak errors I assumed that it must be the sensor on the canister but no dice. Anybody have any ideas what is going on with this?

BTW I would be very appreciative if anyone has the expected voltage/resistance/etc for the canister module so I can at least check the damn thing with a voltmeter and hope to chase it back to the ECM. I have the wiring diagram.

Background impacting this issue:
- New IAG Stage 2 FA20 12.5:1 (newly installed by 'high end' performance shop after Toyota destroyed my engine with the valve spring recall...)
- Edelbrock SC with Delicious Tuning FlexFuel kit (updated tune but having issues getting it done due to this problem/ currently running pump gas)
- New fuel pump, fuel pressure sensor, and Radium fuel filter (fuel pressure is good)
- New fuel pump hanger (and hanger on the other side). Both threaded locking caps and gaskets seem fine and in place but I have not done a pressure test on the tank...)
- New evap solenoid
- New gas cap
- New charcoal canister
- New canister pump module (sensor unit next to the charcoal canister)
- All hoses/connectors I could see appear in decent shape.

The only screwy thing is the performance shop initially put the wiring harness for the evap solenoid from the edelbrock kit and not the DT kit onto the evap solenoid. They then doubled back the DT kit plugs onto themselves. Weirdly this keeps the supercharger coolant pump from running. They ran the car 500 miles at low/mid RPM during break in an never caught it. After correcting the wiring everything seems to work, but I still get the 451 code. No clue if this would have anything to do with it but...

There are a lot of other mods but they likely would not impact this.

[Ashikabi]

Originally Posted by Bunsin

It's been a long ride, but at this point I'm getting close to the end of my rope...



I have a CEL with a P0451 code that I can not figure out where it is coming from and no amount of searching for this specific to our cars is yielding results. I just got done replacing the evap canister and canister pump module (yes getting those out is a pain even after dropping the dif) and I am still getting this damn error (shows up after 2 starts). Odd thing is it is the only error I get (i.e. no large of small leak errors). However, as the car drives it causes issues with running due to what I assume the learning part of the ECM and the interplay with the evap solenoid. Clearing the error even when the evap solenoid is deleted from the 'circuit' changes the engine RPM so it is still effecting the learned part of the tune regardless (went into limp mode on one trip when the evap solenoid was in and tank was full). Given there are no leak errors I assumed that it must be the sensor on the canister but no dice. Anybody have any ideas what is going on with this?



BTW I would be very appreciative if anyone has the expected voltage/resistance/etc for the canister module so I can at least check the damn thing with a voltmeter and hope to chase it back to the ECM. I have the wiring diagram.



Background impacting this issue:

- New IAG Stage 2 FA20 12.5:1 (newly installed by 'high end' performance shop after Toyota destroyed my engine with the valve spring recall...)

- Edelbrock SC with Delicious Tuning FlexFuel kit (updated tune but having issues getting it done due to this problem/ currently running pump gas)

- New fuel pump, fuel pressure sensor, and Radium fuel filter (fuel pressure is good)

- New fuel pump hanger (and hanger on the other side). Both threaded locking caps and gaskets seem fine and in place but I have not done a pressure test on the tank...)

- New evap solenoid

- New gas cap

- New charcoal canister

- New canister pump module (sensor unit next to the charcoal canister)

- All hoses/connectors I could see appear in decent shape.



The only screwy thing is the performance shop initially put the wiring harness for the evap solenoid from the edelbrock kit and not the DT kit onto the evap solenoid. They then doubled back the DT kit plugs onto themselves. Weirdly this keeps the supercharger coolant pump from running. They ran the car 500 miles at low/mid RPM during break in an never caught it. After correcting the wiring everything seems to work, but I still get the 451 code. No clue if this would have anything to do with it but...



There are a lot of other mods but they likely would not impact this.

Use the tune to shut off the code. Delete the evap. Problem solved

Sent from my ONEPLUS A5010 using Tapatalk

[Bunsin]

Originally Posted by Ashikabi

Use the tune to shut off the code. Delete the evap. Problem solved

Sent from my ONEPLUS A5010 using Tapatalk

I deleted the evap solenoid (as it is normally closed you can just unplug it and it will act as a closed loop to the tank). The engine still has issues with it as the learning function seems to take into account the reading it is getting from the canister and tries to adjust? I assume that suppressing the code in the tune will not fix that problem. I'll admit I could be wrong here but then why when the P0451 code is cleared (with the solenoid deleted) does the engine RPMs change and it seems to drives better. I also posed the question to Bill at DT and he indicated it was running a bit rich without it in... Very odd but there it is. What is not clear to me is how the program deals with deleting sensor data as it queries the sensor when above 3/4 and below 1/4 tank (you can see this on the P3 gauge) and checks the sensor every other startup for the CEL. At this point I would prefer to figure this problem out instead of delete a sensor and suppress the CEL.

BTW AFR, LTFT and STFT seem fine when everything is cleared and not in check mode at the sensor.

[Ashikabi]

Originally Posted by Bunsin

I deleted the evap solenoid (as it is normally closed you can just unplug it and it will act as a closed loop to the tank). The engine still has issues with it as the learning function seems to take into account the reading it is getting from the canister and tries to adjust? I assume that suppressing the code in the tune will not fix that problem. I'll admit I could be wrong here but then why when the P0451 code is cleared (with the solenoid deleted) does the engine RPMs change and it seems to drives better. I also posed the question to Bill at DT and he indicated it was running a bit rich without it in... Very odd but there it is. What is not clear to me is how the program deals with deleting sensor data as it queries the sensor when above 3/4 and below 1/4 tank (you can see this on the P3 gauge) and checks the sensor every other startup for the CEL. At this point I would prefer to figure this problem out instead of delete a sensor and suppress the CEL.



BTW AFR, LTFT and STFT seem fine when everything is cleared and not in check mode at the sensor.

Is it not possible to stop the ECU from checking for the sensor? Race applications won't have evap, they must deal with this somehow. If not I guess spoofing the sensor would be the next logical thing to try but I don't know how to do that. I'm certain it can be done though. Otherwise in an incredibly extreme and expensive attempt to "fix" it, you could replace your ecu with a standalone like the Hydra, which won't care at all about evap.

Have you talked to Zach yet? He might know something that Bill doesn't. He's one smart cookie. Zach isn't with Delicious anymore. I don't recall which shop he went to... Racers line? Counter space garage?

Sent from my ONEPLUS A5010 using Tapatalk

[airrick]

https://www.ft86club.com/forums/showthread.php?t=88940

Old thread that talks about potential resolution. Usually if youre getting evap codes and youre using a flex fuel kit or aftermarket market 02 sensor, one of those uses the evap input so you’ll need to get it disabled in your tune. Thats what my tuner did. I didnt have P0451 like yours but i had a few like P0452 after i used the evap input for my wideband 02 sensor