Yes and the main dealers have run out of ideas as well and at this point suggesting continuing to replace random parts until the problem may be resolved. Catalytics have been suggested, as well as fuel injectors and HP pumps, perhaps even another new LP pump. Diagnostics they've done to the evap system and vacuum lines have them convinced no faults there (though I agree with you there appears some correlation between my pinpoints and results) Problem is I've replaced a good bit of parts already either myself or by the main dealer, which undoubtedly resolved a number of other issues such as climate malfunctions and noises, viscous fan operation and affects to engine idle, alternator canbus faults, all O2 sensors, LP pump, filter/flange, etc at a substantial cost and their lack of confidence in a specific solution has me hesitant to move forward.

 

I performed a $9 repair procedure tonight and have not had time for a drive but I will say LTFT is sitting between +2 to +12 and no longer at +40. STFT's also more reasonable at 0 to -12 but idle RPM's higher at around 690. Then I turned on the AC and immediately it began doing the 100-150 RPM rhythmic idle drop and shudder which previously, including today would be induced only by a fuel fill up. Turning off the AC had idle return to normal.

And another perplexing new development is a loud whistling noise from the engine which continues even after the engine's shut off until a loud cork like pop and the whistle ceases.

 

That’s progress (I think). What was the $9 repair?

Your fuel trims (added together) are probably close to zero (they’ll probably fatten out as the engine learns new adaptations), and 690 RPMs is not very high - that’s about normal idle, damn close to where mine sits. It’ll vary a little depending on whether the battery is charging or ac is on.

The whistle from the engine - can’t tell you what your sound is for sure, I but I can tell you I’ve had three whistles I’ve dealt with: (1) PCV valve, (2) throttle body, and (3) drivers side valve cover breather hose popped off (connection at the front air intake plenum). The PCV valve would whistle for a couple seconds after shut down as the vacuum left the air intake. Replaced the diaphragm and that fixed it mostly, but still does it once in a while. Throttle body was doing same at some point - cleaned it and that fixed it. When the vacuum hose popped off, that was whistling only while running, but could still be something like that.

 

Drove over 100 miles today with many stops and no MIL or faults so I've certainly resolved yet another issue. And fuel trims have stabilised at around 0%, LTFT and STFT.

The whistle's coming from the throttle body but I suspect it has something to do with the breather or PCV. When the throttle body cycles after shut down, the built up pressure is released, hence the "pop". I reckon this isn't entirely good for the engine and hopefully identify the problem. And yes the $9 part was a new PCV diaphragm. When removing the original, it fell apart with little effort so that was definitely there problem there. Hope the massive money spent on the 6 new O2 sensors accomplished something.

Sadly though the idle issue's still present. Going back to the purge valve for further testing.

 

That’s great. You’re making progress.

As for the “pop” sound, if you’re talking about the puff of air from the throttle body a couple of seconds after engine shutdown, I think that’s normal. Mine does that as well.

My PCV was whistling, so I replaced it with a cheap chinese version - it whistled even worse. So I replaced it again with a land rover OEM part that I bought at the parts counter ($30), but I still don’t know if there was any difference in the part, or if I just didn’t have it placed correctly when I reassembled the first time. I had a hard time getting it back and keeping everything in the right place. When I did it the second time, I took a lot of care using ties to keep the spring compressed etc. Posted about it here: https://www.landroverworld.org/threa...-2#post-221145.

My money is still on the purge valve or charcoal canister for the idle issue. Good luck. Really looking forward to seeing your long saga resolved.

 

The whistle's quite loud, more so at idle. Fuel trims are perfect as is idle (other than the fill up issue). What's annoying is paying the dealer 2 hours of labor to do a smoke test hoping something would be found. I asked about the PCV since that was the most likely to fail and was told a smoke test won't be able to find leaks on a PCV. Then last night I found a video on YouTube of a tech smoke testing the supercharged LR and smoke definitely came out of the vent hole on top of the PCV. For what I paid for a moke test that found nothing wrong I could have bought my own smoke test kit and found it myself!!!!!

As for the PCV replacement, I tried the main dealer first and was told like everything else from JLR NOT ETA on a replacement diaphragm so yes the $9 part was from Amazon. It appears to be same as the original. Replacing was a nightmare, one because of the location and two becuase I tried multiple techniques to make certain it was properly seated and was confident I finally did it on the last try. BUT it is possible the edge perhaps on the rear side came undone. I have another here and suppose could try fitting it as well.

 

I tested the purge again. No vacuum until about 10 minutes when it opens and starts ticking and then there's vacuum so it appears to be working correctly. I'll try it again today when I do a fill.

 

Narrowed it down. After fill up, back to the rhythmic idle drop. Disconnected the line between the purge and the canister and the idle resumed normally, reconnected and back to the idle drop. A generic google search yields hundreds of posts for this same problem, massive RPM drop when refueling, sadly though often times this is accompanied by filling issues or DTCs indicating a failed canister, the obvious culprit or occasionally a fuel filter, tank leak or pump issue though in my case I had this problem prior to fitting a new pump, new filter and new seals.

Could it be the canister despite this still being a problem in cold weather, never overfilled and no filling issues? Canister is inexpensive, comparatively though haven't found any how-toos.

 

Have been following/reading this informative thread as I’m experiencing a similar intermittent engine shudder and hesitation – except mine does so only under load, say driving 10mph up hill. It started doing this after removing air intake to replacing water pump. Prior to replacing water pump, I would MAF MIL every 3K miles or so. Replaced MAF, PCV, filters. Same results. Cyl 5 misfire detected one time. I’m beginning to monitor fuel trim readings using GAP tool. Next course of action would be to replace air intake gaskets (though they’re only 2 year old), front O2 sensors, and clean throttle body. Would resetting fuel trim parameters be advised?

 

I think this could still be the canister. The canister can be saturated without being completely full of liquid fuel (which is, I think, what leads to the problems filling up). When I read your last message and prior posts, it strikes me that you seem to hear your purge valve opening far more often than I hear mine (I can’t remember hearing mine clicking away just sitting at idle). I believe the car opens the valve periodically and, if it senses a lot of richness at the o2 sensor, will keep it open to discharge more fumes. If the canister is saturated, it might just keep opening that purge valve up and might not be able to deal with the overly rich fumes coming in with the closed loop fuel control, leading to the surging idle. Just a theory.

I would replace the canister first, see if that fixes the problem. If it fixes the problem for a while and then returns, that’s when I’d worry about what’s causing the canister to get fuel in it. Could be a filler neck/fuel vapor separator issue or faulty roll-over vent in the tank (not closing when a full tank is sloshing around).