P0453 and P0451 after reverting turbo car back to stock

[mhiscott]

I've just reverted my 2013 FRS back to NA, from turbocharged running Ecutek. It still has the Ecutek cable/dongle paired, but I reverted to the original stock map.

When the car was running the turbo setup, I had wideband o2 assigned to the CPC input wire on the ecu, and I had the evap solenoid output repurposed to drive my 3 port boost controller.

I reverted the ecu wiring on the inputs back to stock, and I reinstalled the evap solenoid under the intake manifold.

I'm now getting two faults, P0453 and P0451 (with P0453 coming back first) when I clear the codes. It only takes a split second for the CEL to come back on after clearing.

Is there anything on the software side of things I could check? Was there anything I needed to revert to stock in Ecutek past what would load when re-writing the oem ZA1JA00C software?

I swapped back out the solenoid under the intake manifold with a spare, all hoses are hooked up correctly, and it still triggers a light immediately.

Thanks for any tips! The car runs great other than this with the original engine reinstalled.

[callisto]

In the service manual, expand "Engine / Hybrid system" to "FA20 ENGINE CONTROL" to "SFI SYSTEM" and then open up the P0451..0453 page:

https://gt86stuff.onrender.com/t3Portal/

It's got a series of diagnostic steps, which may be more detailed than expected - but, it does explain specifically what P0453 means: "EVAP pressure sensor voltage is 4.1 V or more for 1 second: If the canister pressure sensor voltage output (pressure) is 4.095 V: 108.99 kPa(abs) [818 mmHg(abs)] or more, the ECM interprets this as an open or short circuit in the canister pressure sensor or its circuit, and stops the EVAP system monitor."

It specifically calls out three causes:

• Wire harness/connector (ECM - Canister pressure sensor)
• Canister pressure sensor
• Open in ECM circuit

There's another forum post that talks about P0453 after a revert due to a wire being loose into the ECM:

https://www.ft86club.com/forums/showthread.php?t=136041

So that might be a useful first step to check.

[mhiscott]

Thanks callisto! I'll have to meter the pressure sensor if that seems to be what's in need of replacement.

I can do a continuity check on the wiring from the ecm as well.

I'm going to take one last look at the ecu. I recently pulled it to check the wiring, having found that same thread you linked. It sounded like the exact same issue, but I checked (so I thought anyways) the wiring was all intact. I'll give it one last check as there are potentially two connections I may have made (could be cpc and rear o2 potentially)

https://www.delicioustuning.com/node/848

Here are some other good diagrams showing the whole system

https://www.ft86club.com/forums/show...70&postcount=5

[callisto]

(Also, I missed your software question, sorry - I haven’t seen anyone reporting evap stuff persisting across an ECU reset without it being a mechanical issue.)

[mhiscott]

I just went over some back and forth e-mails with the tuner from back in the day, as well as pulled down the ECU to inspect the wiring.

I had been using the CPC input as a trigger from my meth injection controller (0-5v switched), as well as the wideband input into the rear o2 wire. The rear o2 wire was snipped, but is reconnected and soldered/heat shrinked.

Nothing weird on that side of things really. The float/fuel pump setup was out since the car was running is the only other thing I can think of.

Is the canister pressure sensor built into the charcoal canister which is in the rear right wheel well? I suppose swapping that out for another one would be the next move.

[mhiscott]

Originally Posted by callisto

(Also, I missed your software question, sorry - I haven’t seen anyone reporting evap stuff persisting across an ECU reset without it being a mechanical issue.)

Thanks - That was what I was worried of, potentially race rom still having the output to the CPC solenoid (which likely has to be working properly for the EGR to operate properly and be CEL free) highjacked for the boost controller I was using previously.

So long as flashing a stock ROM on undoes any racerom mapping - everything should be fine.

[callisto]

Originally Posted by mhiscott

Thanks - That was what I was worried of, potentially race rom still having the output to the CPC solenoid (which likely has to be working properly for the EGR to operate properly and be CEL free) highjacked for the boost controller I was using previously.

So long as flashing a stock ROM on undoes any racerom mapping - everything should be fine.

I think the only thing _I_ know for sure it won’t undo across ECU wipes is the one VVT cam position thing that’s stored in EEPROM? But I’m not a pro tuner..

[mhiscott]

It looks like there wouldn't be any repurposing of inputs once reflashed to stock. There are no "race rom options" showing on the original tune.

I did a couple of checks today - I pulled the passenger rear arch liner, exposing the fuel tank vent. I made sure there was nothing obstructing the vent which there wasn't. I also checked for leaks by blowing into the fuel tank vent hose at the filler neck. There were no leaks and you could feel/hear the plastic fuel tank expand when blowing into it. I did the same test with the fuel cap off, and (as expected) the air I was blowing in through the vent would just escape through the fuel cap with it off. A third test was blowing into the vent tube with the fuel cap sealed, but the vapor line to the engine bay open. As you'd expect, when blowing into the vent tube at the back of the car, with the vent hose unhooked at the solenoid under the intake, the excess air would bleed out from the tank to the front of the car (also as expected).

So everything pretty well tests fine as far as the system having no leaks and the hoses sending fuel vapor to the front as they're designed to.

According to Toyota's documentation, the P0453 CEL is triggering due to a >4.1V signal (>109 kpa) at the tank pressure sensor (which is above the differential, tied into the charcoal canisters etc). This can't be the case though, as I still get this code immediately even when the fuel cap is off (which wouldn't allow the tank to pressurize at all, let alone above the max value the ECU needs to trip a code).

Based on the troubleshooting results, I'm inclined to think the "canister pump module" is bad - but I have my doubts changing it will solve the issue.

[mhiscott]

I ordered a used ELCM on ebay which will arrive in a couple weeks.

In the mean time, I metered the CPC solenoid under the IM, and (as indicated in the wiring diagrams) one pin was switched 12v, I would have expected the other pin to be switched ground from the ECU, but it actually sits at 3v with the ignition on.

Is this normal? I would expect to see any voltage on a ground trigger on the ECU side...

[mhiscott]

Originally Posted by mhiscott

I ordered a used ELCM on ebay which will arrive in a couple weeks.

In the mean time, I metered the CPC solenoid under the IM, and (as indicated in the wiring diagrams) one pin was switched 12v, I would have expected the other pin to be switched ground from the ECU, but it actually sits at 3v with the ignition on.

Is this normal? I would expect to see any voltage on a ground trigger on the ECU side...

Apparently this is normal and is likely a pull up resistor holding the ground trigger at 3.3v until it flips to ground and triggers the solenoid....

Oh well...keep digging...

[AussieBRZ]

Originally Posted by mhiscott

I've just reverted my 2013 FRS back to NA, from turbocharged running Ecutek. It still has the Ecutek cable/dongle paired, but I reverted to the original stock map.

When the car was running the turbo setup, I had wideband o2 assigned to the CPC input wire on the ecu, and I had the evap solenoid output repurposed to drive my 3 port boost controller.

I reverted the ecu wiring on the inputs back to stock, and I reinstalled the evap solenoid under the intake manifold.

I'm now getting two faults, P0453 and P0451 (with P0453 coming back first) when I clear the codes. It only takes a split second for the CEL to come back on after clearing.

Is there anything on the software side of things I could check? Was there anything I needed to revert to stock in Ecutek past what would load when re-writing the oem ZA1JA00C software?

I swapped back out the solenoid under the intake manifold with a spare, all hoses are hooked up correctly, and it still triggers a light immediately.

Thanks for any tips! The car runs great other than this with the original engine reinstalled.

If you have put in stock tune and put back all wiring and sensors to stock


Then
You have wiring or sensor issue
Or you got an evap hardware issue like leak


You can kill those codes on stock tune but then it's not stock and likely won't pass emmissions

[mhiscott]

Well I replaced the ELCM today with a used one from eBay, and it fixed it!

Took about 4 hours to drop the rear subframe, replace the egr unit, and put everything back together.

Idles now with no CEL.