Pesky Evap Emmisions code

ianyboy · May 20, 2014

I ve got a 2011 Ranger, 4.0L. Ive got a couple (if not all) evap emmision codes popping my CEL. Ive looked at AllData, they tell me to check the FTP (fuel tank pressure) sensor. Ok, sooooo, where is it?

RonD · May 20, 2014

Need the codes, all of them.

EVAP system codes are usually not specific even when they appear to be, lol.

Fuel tank pressure sensor is located above the fuel tank, fuel tank needs to be dropped to access it, or bed removed which is sometimes easier.
Look here: http://www.autozone.com/autozone/repairguides/Ranger-2008-2009/Components-Systems/Fuel-Tank-Vapor-Pressure-Sensor/_/P-0996b43f80e64255

Fuel tank pressure is also dependent on gas cap and filler hose being able to hold pressure, so a loose gas cap or crack in the filler hose will show as fault in EVAP system.

Same with a loose wire for a sensor, or faulty solenoid that holds the pressure in.

ianyboy · May 20, 2014

So, I just went and pulled my codes, I've got 6 (or 3). Basically, this is how the read out:
1 - P0446
2 - P0451
3 - P0453
4 - P0446
5 - P0451
6 - P0453

Yes, I know, codes 4-5-6 are repeats of 1-2-3. I still put em in as the OBD2 reader gave em to me, if that gives any info on the problem

Also, I am from Canada (canadian Ranger), with a 3in PA body lift

RonD · May 20, 2014

Yes, 4-5-6 are history codes, 1-2-3 are current, all EVAP related

The EVAP system does one thing and because it is Emissions related it will turn on CEL when a problem is detected.
The EVAP system prevents gas fumes from exiting the fuel tank........that's it, that's all it does.
When you turn on the key the Vent Valve will get 12volts and Close, this allows the EVAP system to maintain pressure once engine is started.

Code P0446 could mean one or more of the following has happened:
Faulty vent valve
Open, short or excessive resistance on Vent valve control circuit.

So vent valve is most likely the source of the problem and causing the other two codes.
Finding the Vent valve location on a 2011 will be the issue, my best guess would be at the fuel tank.

The vent valve is just an on/off solenoid, it's hoses can get clogged as well, so open or closed has the same pressure which would trigger the EVAP CEL

These are most like cause by the above, best guess:
P0451 An improper voltage signal from EVAP control system pressure sensor is sent to Engine Control Module (computer).

P0453 the PCM (computer) noticed the EVAP Pressure sensor or FTP is indicating a higher than normal pressure (above 4.5 Volts) in the EVAP system

You can test the sensor:
Remove the gas cap(remove any pressure in the tank), and turn on the key, with the OBD II readers live scan check the voltage of the Fuel tank pressure sensor, should be about 2.5v with gas cap off.
If it is then problem is not the sensor, if it is above 4v then could be wires or bad sensor, you will need to access sensors connector to find out which

ianyboy · May 20, 2014

Well, I erased the CEL, then went for a drive. As soon as my CEL popped on, I ran the Code Reader, my initial DTC seem to be P0446.
Therefore, I unplugged the Vent Solenoid, quite accesible after removing the spare tire, and put a direct 12v and Ground to it...basically i plugged it onto the battery. It closed as it should with the current on it.

Now, RonD, what means Open, short or excessive resistance on Vent valve control circuit. that you mentioned?

Also, when i turn the engine off, I hear an air leak in the front right wheel area?

Earl43P · May 21, 2014

Under the airbox is the HVAC Vacuum Accumulator.
It is a black sphere with two lines to it.
The line IN has a checkvalve to retain vacuum.
It, or an additional checkvalve is available in the HELP section of most auto parts stores.
It is not unheard of for that black plastic sphere to crack and leak.
It is also relatively common for either of those two lines to crack or break.

A vacuum leak there could easily rob the EVAP system of sufficient vacuum to fail the fuel tank test.

Fix the hissing leak. You may have to remove the airbox to get to and see the sphere. I recall its mount bolts go through the fender liner, removing the RF tire will gain you underside access. Easier than removing the airbox, IMO.

ianyboy · May 21, 2014

Well, with the 3in BL and airbox already gone (got a K&N cold air intake) checking the HVAC accumulator was easy. But, no succes there, all is OK.

I gave a good ear to the hissing though, it originates around this, the AC Compressor

Therefore, the hissing and EVAP have nothing in common. So, other question, is the AC Compressor supposed to emit a hissing sound? I've had AC on all my vehicules, and this is the first time I hear an AC compressor hiss?

RonD · May 21, 2014

ianyboy said:
Well, I erased the CEL, then went for a drive. As soon as my CEL popped on, I ran the Code Reader, my initial DTC seem to be P0446.
Therefore, I unplugged the Vent Solenoid, quite accesible after removing the spare tire, and put a direct 12v and Ground to it...basically i plugged it onto the battery. It closed as it should with the current on it.

Now, RonD, what means Open, short or excessive resistance on Vent valve control circuit. that you mentioned?

Also, when i turn the engine off, I hear an air leak in the front right wheel area?

I would test the voltage on the connector for the Solenoid vent valve, with key on it should be 12volts.
Also check the OHMs on the solenoid, I would expect 200-400ohms, but don't have the specs on it, lower ohms or higher ohms could trigger that p0446.

The air leak sound could be normal but I would try to track it down.

adsm08 · May 21, 2014

That's not the AC compressor. The orifice tube is in that general vicinity though, and it is the designed restriction that lets AC make things cold. It will hiss if the system was running as the high and low pressure sides of the system equalize.

ianyboy · May 21, 2014

Thanks for the explanation asdm08. And RonD, i will check my voltages and resistance tomorrow. If all else fails, I guess I will have to become buddies with that darn CEL

ianyboy · May 29, 2014

Sry for the late come-back on this topic. I've checked that solenoid and its connector. Truck is sending .4 VDC (checked with 2 different testers) to the plug. Also, solenoid is at 57.some Ohms?

Pesky Evap Emmisions code

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