First-time post for me, which isn't too bad since I've had my LR3 for six months without a problem...until now. 2006 with 76,000 miles, the common "loose gas cap" warning message came up. Cap looked original so I changed it for an OEM. Cleared the fault message with GAP tool. The message returned but this time I got the P0442 code but no check engine light. I found several threads on the issue and followed the posted recommendations. Smoke test, pass. Swapped out DMTL pump (OEM) on the charcoal canister. After I cleared the warning message, a few days later, got the P0441 code this time with the check engine light. Swapped out the fuel vapor canister purge valve (OEM $$) on the engine. The code came back. The charcoal canister appears intact, and there doesn't appear to be any liquid gas in it. I don't top off and there's no problem filling the tank. The engine runs fine; however, the moment I clear the codes with the GAP tool, the engine idle pops from 650 rpm to 1200 for about a minute and then settles back down. I can't find any forum thread that references this symptom and I concede I might not have looked hard enough. I'm going to perform another smoke test but any thoughts would be greatly appreciated, especially with regards to the idle symptom.

 

Def do a smoke test. Unless you can easily remove the purge valve behind the engine I would put the smoke into the filler cap and seal it off. I would also just disconnect the evap line at engine after the valve, then you will know if the new valve is closing. Maybe an o-ring on one of the crappy plastic pipes got damaged. A tiny, tiny hole can cause a lot of an issues - just like a hole in a drinking straw. I am not sure about the engine surge, if EVAP is an issue for engine performance I would expect lean codes to pop up too.

 

Thanks. Much appreciated. I'll run the test Saturday per your suggested method. I'm going to check the wiring too in case it's shorting out somewhere. I'll report back.

 

Hi I am curious if you ever found out what the issue was? I just picked up an LR3 and I believe it has some EVAP issues, but I am still learning what all they might be. It has the common suction in the fuel tank causing the sort of farting noise at the fuel cap. The fuel cap is broken so I have ordered a new one. I also have suction at the purge valve. I pulled it off while the engine was running and it was pretty tough to pull off. I didn't check at the manifold, which I guess would indicate a stuck open valve, so I will do that today. But I have yet to get GAP tool so not sure if I have codes, currently no CEL though.

I had not had any drivability issues until yesterday, I was driving back to the office and the car felt like it was struggling for power at a normal pedal position. I felt like I had to press it a little deeper to get going. The car also sounded louder like it was in Cat heat up mode. It stayed like this for the entirety of the 1.5 mile trip, when I parked it, the idle was stuck at about 1200 rpm. I also got an emergency brake system fault warning, as pulled into the garage which may explain the lugging feeling? But the idle shouldn't be related to that. I shut everything down and went back to work. When I came out a few hours later and started the vehicle it again sounded very loud and was idling at 1200 rpm. I gave it a tap of the throttle like you would do for a stuck carburetor and it settled down. After that I drove home with no issues and again ran some errands later in the evening with no issues. I am wondering if I have a faulty purge valve, so I will see if I can diagnose that a bit more. Thoughts on what else it might be?

 

Smoke test revealed nothing. I will confess, I have yet to crawl through the entire length of the truck as it's been chilly of late in CO and with no adverse symptoms, I've easily talked myself into waiting. I've replaced the pump, valve and gas cap.
You appear to have symptoms that I don't, so I suspect you will find another issue/cure. I think I either have the tinniest of leaks but sufficient fail the test, or I have a wiring issue. I'm still assuming a leak is the most likely. The only odd "symptom" I'm getting it a short term high idle when I clear the code with the GAP tool. I don't have any other engine codes, only a few U "lost communication" with transfer case etc. The idle settles back down after about 30 seconds. I'm currently in the CO mountains @ -15F - not Canada cold but bloody cold enough for me to avoid crawling under my Disco!
I will report back once I've, hopefully, figured it out.
​​​​​​

​​​

 

@benijohnson - You sound like you are on the right path. The EVAP system has just one port to vacuum as you found. There should be no suction past that valve when the engine is cold. This is a good read from the shop manual on how the system works, it may give you some direction on problem solving. But I will add that you can operate with the EVAP disconnected for a short while and see how things work. Simply remove the vac line to that solenoid and cap off the intake. If you have a radical change in engine behavior then all fingers point to EVAP system.

PDF is for 4.4L NAS:

 

Can anyone tell me where the purge valve is located on the LR3 Disco? And maybe the general way I can get to it? I am thinking about replacing it.

 

It's attached to the rear of the engine about 10 inches down, middle left as you face the engine bay. Go to the Atlantic British website or any Land Rover parts website and search for the part, you will see the entire part, tubing included. That makes it easier to locate -the tubing is routed on top of the engine. I couldn't find an OEM valve without the tubing. You'll likely need to replace the whole thing. The AB OEM (not the more expensive Land Rover original) part has worked for me so far. It's an easy swap out.