EVAP system.. WTF?? - Ranger-Forums - The Ultimate Ford Ranger Resource


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  #1  
Old 10-11-2005
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EVAP system.. WTF??

Okay, I was checking my trucks ECU with an OBD-II scan tool by actron and I figured while I was at it I would check the emissions systems too..

Well, I have NO check engine codes and all the systems but one said "NOT READY"

EVAP.....

Now the scan tool manual says that Not Ready could mean the system is not working or could mean that there have not been enough drive cycles for the data to be reported...

Okay, sure... What is the Evaporative Emmisons System?? The scan tool book only talks about codes.. It doesn't get into the monitor stuff...

I hope someone can shed some light on this please.. I don't know if something is wrong with the truck or just not in use right now...
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Old 10-11-2005
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This is my best guess. I think that is a charcoal cannister. The fuel tank has to vent. It vents through the cannister and then it is fed into your intake to be burned off. My VW Thing and my s-10 have one so I would assume all vehicles probably have one.
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Old 10-11-2005
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I only have an intake, and an exhaust and i just hit 14K miles... Do you think that there just isnt enough data for it to trigger as ready or do you think that canister could be plugged??
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Old 10-11-2005
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If the light didn't come on, I wouldn't worry about it.
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  #5  
Old 10-11-2005
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The only time drive cycles become an issue is state inspection in states where the OBD-II ystem is checked. Incomplete cycles can be a problem then.

And if there is a gross fault the light will come on. Those drive cycle tests are pretty hard to complete in normal driving sometimes. Takes a lot of miles.
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Old 10-11-2005
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ok.. I know CT does cycle tests but I dont think they use all of them.. Just 02 and Heated 02.
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Old 10-11-2005
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Ok the reason the test is probably not running for ya is the temperature in your area. There is more then likely nothing wrong with your truck, the EVAP system is pretty picky on tripping the check engine light. There is a certain temperature threshold of too low of a temp and too high of a temp on startup that will disable the test from running. Alot of colder climate areas you will never see that test run in the winter unless you have a heated garage.

The system basically takes the fuel vapors from the tank and utilizes the purge valve to take them to the engine and keep them out of the outside air. I wouldnt worry about it too much, if you can find out the temperature thresholds that would tell you more, I dont have access to that information for Fords, only GM.
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Old 10-11-2005
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04lvl2...

Thanks soo Much!! that makes perfect sense.. It stopped responding as ready when the cold rainy weather set in... It was like 70's 80's then all of a sudden dropped to 40's and 50's... Plus it's rainy as hell...

I bet thats it, the temperature dropped so it doesn't run cause other cars i checked at work all had NO check engine lights but the EVAP system said NOT READY...


Thanks for the tip, I will call Ford 2maro and check the temp threshold on that..
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  #9  
Old 10-12-2005
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when was the last time you had your gas cap off?

if the tank has not pressurised then the system is "not ready" it has nothing to due with air temp.
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Old 10-12-2005
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Quote:
Originally Posted by VulcanMotor~PowerHouse
04lvl2...

Thanks soo Much!! that makes perfect sense.. It stopped responding as ready when the cold rainy weather set in... It was like 70's 80's then all of a sudden dropped to 40's and 50's... Plus it's rainy as hell...

I bet thats it, the temperature dropped so it doesn't run cause other cars i checked at work all had NO check engine lights but the EVAP system said NOT READY...


Thanks for the tip, I will call Ford 2maro and check the temp threshold on that..
Your very welcome, check the conditions for running the test and that will tell you alot about when it will run of course.
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  #11  
Old 10-13-2005
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Here is some more information

The Evaporative Emission (EVAP) Leak Check Monitor is an on-board strategy
designed to detect a leak from a hole (opening) equal to or greater than
1.016 mm (0.040 in.) in the Enhanced EVAP system. The proper function of
the individual components of the Enhanced EVAP system as well as its
ability to flow fuel vapor to the engine is also examined. The EVAP Leak
Check Monitor relies on the individual components of the Enhanced EVAP
system to apply vacuum to the fuel tank and then seal the entire Enhanced
EVAP system from atmosphere. The fuel tank pressure is then monitored to
determine the total vacuum lost (bleed-up) for a calibrated period of
time. Inputs from the Engine Coolant Temperature (ECT) or Cylinder Head
Temperature (CHT) sensor, Intake Air Temperature (IAT) sensor, Mass Air
Flow (MAF) sensor, vehicle speed, Fuel Level Input (FLI) and Fuel Tank
Pressure (FTP) sensor are required to enable the EVAP Leak Check Monitor.

NOTE: During the EVAP Leak Check Monitor Repair Verification Drive Cycle a
Powertrain Control Module (PCM) reset will bypass the minimum soak time
required to complete the monitor. The EVAP Leak Check Monitor will not run
if the key is turned off after a PCM reset. The EVAP Leak Check Monitor
will not run if a MAF sensor failure is indicated. The EVAP Leak Check
Monitor will not initiate until the Heated Oxygen Sensor (HO2S) Monitor
has completed.

The EVAP Leak Check Monitor is executed by the individual components of
the Enhanced EVAP system as follows:
1. The function of the EVAP canister purge valve is to create a vacuum
on the fuel tank. A minimum duty cycle on the EVAP canister purge
valve (75%) must be met before the EVAP Leak Check Monitor can
begin.
2. The Canister Vent (CV) solenoid will close (100% duty cycle) with
the EVAP canister purge valve at its minimum duty cycle to seal the
Enhanced EVAP system from atmosphere and obtain a target vacuum on
the fuel tank.
3. The Fuel Tank Pressure (FTP) sensor will be used by the EVAP Leak
Check Monitor to determine if the target vacuum on the fuel tank is
being reached to perform the leak check. Some vehicle applications
with the EVAP Leak Check Monitor use a remote in-line FTP sensor.
Once the target vacuum on the fuel tank is achieved, the change in
fuel tank vacuum for a calibrated period of time will determine if a
leak exists.
4. If the initial target vacuum cannot be reached, Diagnostic Trouble
Code (DTC) P0455 (gross leak detected) will be set. The EVAP Leak
Check Monitor will abort and not continue with the leak check
portion of the test. For some vehicle applications: If the initial
target vacuum cannot be reached after a refueling event and the
purge vapor flow is excessive, DTC P0457 (fuel cap off) is set. If
the initial target vacuum cannot be reached and the purge flow is
too small, DTC P1443 (no purge flow condition) is set. If the
initial target vacuum is exceeded, a system flow fault exists and
DTC P1450 (unable to bleed-up fuel tank vacuum) is set. The EVAP
Leak Check Monitor will abort and not continue with the leak check
portion of the test. If the target vacuum is obtained on the fuel
tank, the change in the fuel tank vacuum (bleed-up) will be
calculated for a calibrated period of time. The calculated change in
fuel tank vacuum will be compared to a calibrated threshold for a
leak from a hole (opening) of 1.016 mm (0.040 in.) in the Enhanced
EVAP system. If the calculated bleed-up is less than the calibrated
threshold, the Enhanced EVAP system passes. If the calibrated
bleed-up exceeds the calibrated threshold, the test will abort and
rerun the test up to three times. If the bleed-up threshold is still
being exceeded after three tests, a vapor generation check must be
performed before DTC P0442 (small leak detected) will be set. This
is accomplished by returning the Enhanced EVAP system to atmospheric
pressure by closing the EVAP canister purge valve and opening the CV
solenoid. Once the FTP sensor observes the fuel tank is at
atmospheric pressure, the CV solenoid closes and seals the Enhanced
EVAP system. The fuel tank pressure build-up for a calibrated period
of time will be compared to a calibrated threshold for pressure
build-up due to vapor generation. If the fuel tank pressure build-up
exceeds the threshold, the leak test results are invalid due to
vapor generation. The EVAP Leak Check Monitor will attempt to retest
again. If the fuel tank pressure build-up does not exceed the
threshold, the leak test results are valid and DTC P0442 will be
set.
5. If the 1.016 mm (0.40 in.) test passes, the test time is extended to
allow the 0.508 mm (0.020 in.) test to run. The calculated change in
fuel vacuum over the extended time is compared to a calibrated
threshold for a leak from a 0.508 mm (0.020 in.) hole (opening). If
the calculated bleed-up exceeds the calibrated threshold, vapor
generation is run. If vapor generation passes (no vapor generation),
an internal flag is set in the PCM to run a 0.508 mm (0.020 in.)
test at idle (vehicle stopped). On the next start following a long
engine off period, the Enhanced EVAP system will be sealed and
evacuated for the first 10 minutes of operation. If the appropriate
conditions are met, a 0.508 mm (0.020 in.) leak check is conducted
at idle. If the test at idles fails, a DTC P0456 will be set. There
is no vapor generation test with the idle test. NOTE: If the vapor
generation is high on some vehicle Enhanced EVAP Systems, where the
monitor does not pass, the result is treated as a no test. Thereby,
the test is complete for the day.
6. The malfunction indicator lamp (MIL) is activated for DTCs P0442,
P0455, P0456, P0457, P1443 and P1450 (or P446) after two occurrences
of the same fault. The MIL can also be activated for any Enhanced
EVAP system component DTCs in the same manner. The Enhanced EVAP
system component DTCs P0443, P0452, P0453 and P1451 are tested as
part of the Comprehensive Component Monitor (CCM) .
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Old 10-14-2005
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Bill, is that text ^^^ from Ford or GM? Looks like Ford but I wanted to be sure.
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  #13  
Old 10-14-2005
04 EDGE
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its not all-data, i was checking a evap ayatem on a chevy today, same sort of wording but different
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  #14  
Old 10-14-2005
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Its from Ford but it came from All-Data as that is all the Ford information that I have.
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