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Researching and errands to run so may not be back for a while
Swapped the relay before the F14 fuse ?
I can't remember the name without looking it back up
You don't necessarily need a extra unwanted draw across the relay but a normal condition draw if the contacts are bad it will trade voltage for normal current which it can't satify
@Parker 7 Unfortunately, I'm fairly certain that R11 is one of the soldered relays on the Front Power Distribution Box. It can't be swapped.
As an update, I put a stethoscope on each of the fuel injectors and each are ticking away, with no discernible difference between each injector. They are obviously getting power, even if I can't measure it at the fuse.
Quick update on my situation.
I checked my part-load breather and all is fine with it. However, there was a problem with the o-rings. There are two that should be the same size, I reckon, but in my case they were each different. One was 17.0mm x 3.0mm and the other was 16.0mm x 2.3mm. The diameter of the o-ring seat is 16.8mm. I tried testing it with some new 16.0mm x 2.5mm, but there was no drag when I inserted them into the breather, so I am going to order some new 17.0mm x 3.0mm NBR o-rings from the o-ring store, LTD, which should be the correct fit. I will also just order the other vacuum o-rings to refresh them all. In the meantime, I will soak my old o-rings in a wintergreen/ethanol solution to restore them a bit.
The only people that have been in this car are myself, an independent Jaguar mechanic, and the dealership according to the records...
If someone wanted to be helpful, could you measure voltage at F12, F13, and F14 in the Front Distribution Power Box, with the engine running to see if what I am measuring is out of whack with what you are measuring?
Thanks very much
Apologies, I'm an idiot @Parker 7 , my test clip to ground had slipped onto a painted surface, which is why I was getting the odd readings. With the engine running F12-F14 are all at 14V.
I measured the three ten amp fuses at F12-F14 in the front power distribution box and got 14.5 volts at all three while the engine was running.
Also, I saw no change in my lean-when-cold condition after servicing the EVAP and CCV o-rings, although it may improve my overall vacuum leak situation. I'll find out when I take it for a drive and get it up to operating temperature.
UPDATE -- I think I have it sorted (though I hesitated to type that for fear I'll be back admitting defeat)
I know I had possibly two distinct issues, one that the wrong MAF sensor for months may have resulted in odd adaptations that were confusing the ECM. And two, the fact that I could reproduce the Check Engine/Restricted Performance as I listed above, and that sitting overnight was involved in setting up the failure.
Here's the steps I took in case it helps someone else.
I. Went through all the pinpoint tests in the Workshop manual regarding the MAF Sensor to make certain there were no wiring or ground faults, and monitored fuel trims and MAF sensor signals to see the MAF performing correctly.
2. I performed the HO2 Sensor Drive Cycles I found in a post over on the S-Type forum: https://www.jaguarforums.com/forum/s...-198690/page3/
In hopes of separating the adaptations from the other issue, and it appears to have worked. After the overnight test, the Restricted Performance was gone, but the Lean Codes and pending MAF Code remained. So what happens overnight? I couldn't find any temperature related faults or bad sensors.
3. As I was waiting for my replacement crankcase breather hose to arrive, I began to wonder if there was significant enough difference in warm versus cold PCV pressures to confuse the ECM. From what I understand, the PCV valve on the normally aspirated 4.2 is more oil separator than typical PCV valve, but maybe I should check it out anyway. When the hose arrived, I also pulled the PCV valve, and it didn't rattle when I shook it, which I believe it should. I also noticed, it was identical to the PCV valve on my Range Rover, so I swapped it over and installed with the new hose (btw, the replacement hose is much more robust than the original, it must be a known fault).
Put it through the usual reproducible steps to trigger the codes, and no Check Engine light or codes recorded. The one issue remaining, is that when you start it cold, there is a momentary instance of a little rough running (max a couple of seconds). Not sure if this will go away as the ECM learns new conditions, or if it is another issue. Other than that, once it settles in it runs beautifully.
Thank you to everyone who helped, either on this thread or all the other ones I read on similar issues.
From what I understand, the PCV valve on the normally aspirated 4.2 is more oil separator than typical PCV valve, but maybe I should check it out anyway. When the hose arrived, I also pulled the PCV valve, and it didn't rattle when I shook it, which I believe it should.
Hold on. Should these definitely rattle? The one on my XJR doesn't and I have been chasing phantom fuel trim issues for months with no joy. Can anyone confirm the PCV valve should rattle? I always just assumed it was an oil sepererator. What happens if it fails?
Hold on. Should these definitely rattle? The one on my XJR doesn't and I have been chasing phantom fuel trim issues for months with no joy. Can anyone confirm the PCV valve should rattle? I always just assumed it was an oil sepererator. What happens if it fails?
Cheers. So the disc shaped thing on Bank 1 is just an oil separator, but on the other end of the hose there is a PCV valve and that should rattle.
Interesting. Will look into that in the morning.
I don't think there's one on the other end, the flying saucer is what they refer to as the PCV valve. Frankly after researching PCV on the X350, I'm more confused than when I started. What exactly the valve does or doesn't do is hard to glean from the documentation or the many posts. Even if it isn't by definition an active valve, I would think the combination of oil/time/heat/ etc. could cause build up or sludge that has an effect on the volume of air going through it, which it turn could cause the ECM to make incorrect assumptions.
I did find several threads regarding other JLR vehicles who use the same flying saucer, that when replacing the PCV valve solved lean code situations. It might be the valve, or it could just be that the o-rings on the new valve did the trick. In my case, I had replaced the o-rings on the old PCV and still had the issue, but swapping it for one from Range Rover did seem to solve it. If you search for it under the Land Rover part number, there are fairly cheap replacements out there if you want to try seeing if that helps your issue.
Hahahahaha, I knew I shouldn't have tempted the Jaguar gods and posted that I had it sorted. I even waited several days of good running before posting. Fooooooool...
Went to pull the car out to make some room in the garage, and as I was backing out the Check Engine Light and Restricted Performance message popped up.
Check codes and it's the same Lean Codes for Bank 1 and 2.
So forget everything I said above, and excuse me while I go bang my head against a brick wall.
It is on the 'part-load' branch of the CCV system, suggesting that it's responsibility is to operate under partial load conditions. Partial load suggests to me that this part of the CCV system only begins to ventilate at or above partial load, and below this threshold there is no ventilation. So either there is a valve elsewhere in the pathway, the saucer itself acts as valve of sorts, or it is somehow a passive system that is triggered through the physics of the engine.
I believe the most parsimonious explanation is the saucer, which I understand it to have a diaphragm, somehow restricts ventilation at low loads. @EsRay and others have pointed out that if you block the inlet on the saucer and apply suction to the outlet, the diaphragm closes. This makes a lot of sense, in that when vacuum is high, i.e., at low load, the diaphragm should close. The main issue I see is that there needs to be resistance at the inlet of the saucer, which I don't understand under which conditions that would happen. Even at idle, there is some positive pressure.
SInce @Mac Allan has noticed an improvement following the swap, one has to think the old saucer-shaped thing had been faulty. I do think it has been warmer in my part of california this week, which could also be a factor, I don't know. My car only threw codes when it was much colder and now seems fine, except the fuel trims suggest that the problem is only reduced rather than corrected. I would love to see the fuel trims when using both of the saucers on @Mac Allan 's car to see what effect the swap has on the trims.
I worry that perhaps we're overthinking the influence of this part on the air/fuel ratio under low-load conditions.
We are talking about a very specific car here, that doesn't seem to have a PCV Valve in the classic sense. The oil separator definitely doesn't rattle.
03-20-2022 | 04:20 PM
