EVAP fuel tank pressure sensor

My sensor looks to have went out, or possibly has come loose. It reads 64-65k 99 percent of the time with the engine running. It does read a proper value if the engine is off.

Car was acting like it had a intermittent vacuum leak. Both this sensor appears broken and the purge valve would stick.

Car ran like shit, rpms would hang during shifts, and trims were all over the place.

No codes or check engine lights. Is there a way to force a evap check outside the dealer scan tool?

superman07 said:

My sensor looks to have went out, or possibly has come loose. It reads 64-65k 99 percent of the time with the engine running. It does read a proper value if the engine is off.

Car was acting like it had a intermittent vacuum leak. Both this sensor appears broken and the purge valve would stick.

Car ran like shit, rpms would hang during shifts, and trims were all over the place.

No codes or check engine lights. Is there a way to force a evap check outside the dealer scan tool?

Click to expand...

I've been rooting around the Helm. All sorts of warning signs about the system being under pressure even when off. I'm reluctant to just start posting stuff I don't have a total grasp and that might lead to your death...

Is the car still under warranty? Any concerns about having the dealer look at it?

Going in Thursday but there are no check engine lights or codes to scan. PID for vapor pressure shows a bad connection or sensor in the fuel line from the canister however the manual shows a subframe removal necessary to get to it. Plugged vacuum port on the purge valve which should have made it better, but it did not. May need to reset KAM. That said stft was still off. The ecu is commanding very high duty cycles for evap purge activity, about 80 percent continuous under cruise only stopping under decel.

There is nothing exposed in HP tuners for the evap logic so I have no clue what else might be an issue. Amazing ca.r can run this shitty without so much as a mil light. It’s the stock ford calibration also.

Interesting enough the manual shows the fuel tank pressure sensor as an embedded componenT in the fuel / vapor line itself and I can’t find a part number or transfer function info.

The car does not have a IAC that I could see from the manual either, I am wondering how the ecu / throttle body handles idle air requirements when the throttle plate closes.

Tank said:

I've been rooting around the Helm. All sorts of warning signs about the system being under pressure even when off. I'm reluctant to just start posting stuff I don't have a total grasp and that might lead to your death...

Is the car still under warranty? Any concerns about having the dealer look at it?

Click to expand...

Fuel system is always under pressure even when car is off. That's why fuel comes spraying out when you disconnect the line from fuel rail. Consider it residual pressure but its there.

Evap seems to be on the other end of the system entirely. The pressure in the fuel rail exists between the hat and pumps and the conclusion of the rail. The evap system monitors tank pressure from the back side, or pump venture side through the canister, vent, and purge valve. technically from what I have read the purge valve and canister solenoid behave the opposite absent power. The valve should be closed, and the vent should be open.

During normal operation the tank should be venting into the canister, then through purge solenoid to the vent. the ecu controls how and when the solenoid is closed. my solenoid may be bad too as I never actually see it close as its duty cycle is 0 percent.

unfortunately the emissions system seems like a black box. Neither the stock tune or the exposed HP Tuners tables gives me any idea of how or why the ecu does what it is doing.

considering it has the ability to introduce both air and hydrocarbons I am surprised there isn't more information.

superman07 said:

My sensor looks to have went out, or possibly has come loose. It reads 64-65k 99 percent of the time with the engine running. It does read a proper value if the engine is off.

Car was acting like it had a intermittent vacuum leak. Both this sensor appears broken and the purge valve would stick.

Car ran like shit, rpms would hang during shifts, and trims were all over the place.

No codes or check engine lights. Is there a way to force a evap check outside the dealer scan tool?

Click to expand...

Sorry man! Just scrubbed through my files and it seems the scan tool is required. As far as I know, no one has figured out how to perform service tasks with FORSCAN either.

Zitrosounds said:

Sorry man! Just scrubbed through my files and it seems the scan tool is required. As far as I know, no one has figured out how to perform service tasks with FORSCAN either.

Click to expand...

The Snap on scan tool is the only aftermarket scanner that I know of that can run OEM tests. But it is pricey.
[ame]

no worries. It goes in tomorrow. I just hope they don't give me the "no mil = no problem" crap

Zitrosounds said:

Fuel system is always under pressure even when car is off. That's why fuel comes spraying out when you disconnect the line from fuel rail. Consider it residual pressure but its there.

Click to expand...

Yup, that’s what I saw in the Manual....many times

Good Luck tomorrow [MENTION=20919]superman07[/MENTION]

superman07 said:

.....The car does not have a IAC that I could see from the manual either, I am wondering how the ecu / throttle body handles idle air requirements when the throttle plate closes.

Click to expand...

A bit of a late response, but since it is DBW, shouldn't the throttle plate be used for idle control? I thought the IAC valves/motors went by the wayside when throttles moved from drive by cable to drive by wire.

I did have a bad purge valve, they will re-check evap but before that they are replacing the manifolds and cats. multiple exhaust leaks.