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2010-2012 Range Rover MkIII / L322
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Discussion Starter · #1 ·
I wanted share some information on EVAP issues, drive cycles and readiness states.
I had an EVAP (P0442) issue and was working my way through possible faults but ran out of time and needed to pass inspection.
In most states you are allowed one not-ready state to pass emission test.

I think the EVAP issues are the hardest to troubleshoot because for any thing you do you have to wait for the EVAP test to run when all conditions become right. There is an EVAP test available in the software and I was hoping that the IIDTool I have would access it. GAP Diagnostic said it was on the wish list but didn't know when they would get to it. As a comparison I have the VAG-COM software for my Audi and the EVAP test is accessible along with the purge valve and several other troubleshooting tests for the EVAP. This is the only down side of owning the Range Rover, the installed base so so small that the available tools and forum help is limited. I posted a message asking about the readiness state of the Fuel System and got zero responses. Hence I am committed to sharing what I find to help others.

Back to the issue.... I kept getting the P0442 fault and was running out of time for the inspection. So my strategy was to reset the fault, prevent the EVAP from running, get the the other readiness states complete and then get inspection with my one allowable not-ready state. I do have to say that in the 2011 the EVAP is a pressure test which I think is a much better system than the vacuum test. The test gets performed after you turn the engine off, in addition to several other conditions. This allows you more control over when the test runs and a much easier system to troubleshoot. The gas needs to be between 15% and 85% for the test to run.... also one other condition that I have not verified is to put the vehicle in low drive before turning it off (I stated to test this but did not verify). This might be the easiest way to prevent the EVAP test.

So now that you have reset the fault and have a strategy to prevent the EVAP test. You will need a way to monitor the readiness states. IIDTool does not do this... I bought a BAFX interface on Amazon for $20 and used Torque Pro ($5) on my Android Phone. The BAFX interface had no issues with the Range Rover, you can get an ELM327 interface for as cheap as $6 on eBay but I have seen posts of issues with the protocol used on Range Rovers.
When you reset the ECU all readiness monitors will show incomplete. There are two drive cycles for the 2010-2012 Range Rovers and probably the same for other years. A short drive cycle and a long drive cycle. The short drive cycle is this.....
4. Start the engine.
Allow the engine to idle for 30 seconds.
Raise the engine speed to 1500 rpm and hold for 3
minutes until a temperature of 70ºC (158 ºF) is achieved.
Allow the engine to idle for 30 seconds.
Switch off the engine.

After this... this is what my readiness states looked like

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All states but 3 were ready... you then do the long drive cycle....
5. NOTE: Make sure cruise control is not engaged.
Make sure the engine temperature is above 60 ºC (140 ºF).
Carry out a road test and perform the following operations.
1. Accelerate to 55 mph (88 km/h) in 5th gear and
cruise for 2 minutes with the engine speed at or
above 1800rpm.
2. Lift off the throttle and allow the vehicle to
decelerate until the engine speed is less than 1000
3. Stop the vehicle.
4. Release brake, allow the vehicle to move with no
throttle for 1 minute.
5. Road test is now complete.

After 2 minutes of driving at 60MPH my O2 Sensor went complete without completing the remainder of the test. I completed the drive cycle twice just to to be safe.
However my Fuel System readiness stayed Incomplete and this is where all my confusion came in. Does the Fuel System monitor depend on any portion of the EVAP test. After a forum post (no response), Torque post (some good info) and hours of searching the web I did not have an answer. However everything I read convinced me that since it was one of the continuous monitors that it should be complete all the time. Since it was not then there was something that had to happen for it to complete. One of the constraints of the Fuel System monitor is that it requires more than 15% gas in the tank to run. There are about a dozen things it monitors to insure that the fuel mixture ratio is correct. My thought was that if any of the sensors were wrong or missing that it would throw a fault (I monitored a lot of these just to verify). So back to constraints... I thought if it needed at least 15% gas then maybe it also had to be less than 85% gas (EVAP condition) for it to run. My big concern here was that if it was not possible to get the Fuel System readiness complete then I was wasting time not resolving my EVAP issue with so little time left. So my next task was to reset the ECU and go through both drive cycles and then continue to drive till my gas tank was below 85%. I did this and no change, so I was going to drive it a day or two and see if the state changed. I pulled in the driveway and put it in LOW Drive to prevent the EVAP test. (was going to verify this lockout strategy now because the drive cycle is very short if you have to reset the ECU) When I pulled into the garage the Fuel System went to complete.

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My conclusion..... is that Fuel System monitor either requires less than 85% gas.... or that it is a mileage constraint... I drove approximately 25 to 30 miles... on most cars there are mileage constraints for certain readiness states. I immediately went and filled up with gas, it took a little over 3 gallons which is very borderline 85%. My money is on the mileage trigger. I immediately went to get an inspection and passed with no issues.

By no means am I advocating not fixing emission issues... however some times with the limited tools us DIY mechanics have... it can not be accomplished in a timely manner and we just need a little more time.

Below is the conditions that have to be met for the EVAP test to run.... I hope this helps anyone that faces this same issue....
The ECM performs a check for major leaks each time the ignition is switched off, providing the following conditions are

The vehicle speed is zero
The engine speed is zero
The pressure altitude (70 kPa (10.15 lbf/in2) derived from engine load calculations) is below 3047 m (10000 feet)
The ambient temperature is between 0 and 40 °C (32 and 104 °F)
The charcoal canister load factor is 5 or less (the load factor is a measure, between -1 and +30, of the fuel vapor
stored in the charcoal canister, where -1 is 0% fuel vapor, 0 is stoichiometric fuel vapor level and +30 is 100%
saturated with fuel vapor)
The fuel tank level is valid and between 15 and 85% of nominal capacity
The engine running time during the previous cycle was more than 10 minutes
The battery voltage is between 10 and 15 volts
The last engine off time was more than 180 minutes
No errors are detected with the EVAP components, the ambient air temperature and the fuel level
High range is selected on the transfer box.
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