Ok, hear me out.

From day 1 of ownership, I have had a quick chatter on startup from the camchains on the motor.
Being a 2003, I was never worried about it being a engine killing scenario and after 7 years of ownership, my motor still runs and still chatters on startup.
Obviously, an oil pressure issue with tensioners but was never really able to track the issue down - at least not easily.
At a turning point now as I have slowly but surely developed a CEL with lean conditions being prevelant and I have thoroughly and repeatedly, investigated the potential issues and have found nothing.
This includes multiple smokings of the engine, only to find the smallest of escapes and not nearly enough to trigger this "permanent" CEL.
It used to come and go and I noticed that when I would trigger a CEL, it was exclusively on initial startup. Never have I gotten a CEL while the engine was already warmed up - always on a cold start.

So, I am working on a theory here that will require a bunch of work to prove or disprove but I plane to go in and do it anyway.
It harkens back to my work on various motorcycle engines and the experience I had with a Suzuki GSXR600 racebike I had been running with my son.
After persistant running issues, I finally stumbled on a potential issue on that motor discovering that the cam chain had stretched to the point of mechanically throwing the cam timing out on the bike.
Once I replaced the cam chain, the motor ran flawlessly so you can see where I am going here.

After years and years of startup chatter, my plausible idea is that over this time, the cam chains have stretched and permanently put my timing out.
It makes mechanical sense to me that if the engine started everytime with the cam chains slackened off due to the tensioners not having oil pressure, that initial slapping of the chain(s) over many years would ultimately lead to some level of stretching of the chains and maybe enough that the cams will never be in time again unless they are replaced.
This issue to be clear, has always been there since I bought the car but the CEL's have gotten progressively worse over the years and now the CEL is permanent.

All coils, plugs, fuel injectors, cam cover gaskets and other associated parts have been changed out over the years and I did enjoy a long time of running without any issues with lean CEL's.
Only over the past year has the CEL for lean conditions become a permanent fixture. I can also hear pinging when I get on the gas low down.
I can still see failing fuel injectors or some problem with ignition casuing an issue like this but I am drawn to the cam chains and timing as I cannot see this chatter being able to go on forever without some stretching of the chains over so many years.
Maybe someone has experience with this type of issue and repair or maybe I am heading down a new road. I have previously solved a serious issue on my car when I discovered that rear wheel bearings were responsible for a myriad of codes being thrown for my transmission. Something that to this day, has never returned.

 

Always is a big help to post what the actual codes are.
Details are needed.
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Trying fitting a new fuel filter before doing anything else.
It is very inexpensive and you can change it yourself.
It is below the car on the left side in front of the rear wheel.
You may know that already but most people forget about the fuel filter because it lasts a long time.

 

If you have the correct cam chain tensioners fitted, they are spring loaded so do not rely wholly on oil pressure unless the spring has broken. If the timing was out so far as to cause a lean engine code, I would expect some cam/crank timing codes to be present. Either way, all the codes need to be analysed.

Richard

 

Maaaan, you been around with these cars, I know. Remember seeing and reading your exploits when I first signed up.

Lazy first questions. Codes on both banks or one?

What are your fueling readings saying when the car is moving? Seem lean?

Lazy O2 sensor(s)?

Then other questions are for my learning... For a slack chain, how does that translate into rich or lean trims? Is a thing having to with chain, translates to cam, and then cams open or close valves early or late? Then, into timing advance. Seems like a slack chain would have some effect on the advance retard set up, but what.

I'll send ya Christmas Cards if ya walk me thru it a bit. I guess it could almost be like you are off,,, or behind a tooth on the timing....?

 

All 4.2s chatter on start up it has nothing to do with timing chains or tensioners It's VVT (Variable Valve Timing) solenoids or seals. Oil runs out of them after they sit overnight and they chatter on start up. Not a biggie they all do it. No codes no idea where to start? No disrespect but I think your assumptions are incorrect and you're heading in the wrong direction. Give us some codes and you know we'll try to help.you figure it out.

 

IF you're getting lean codes on both banks, and pinging, then there's a good change it's the MAF. A flakey MAF will cause a lean condition across the board. A malfunctioning temp sensor may be the culprit, and that's built into the MAF.

 

Hey Lads,

Ok, here is the bevy of codes that I was able to pull with JLR / SDD software.
Some may be older codes that may not be relevant but I am listing all of them anyway.
First up is the batch of misfire codes on all but 2 cylinders:
P0302, P0303, P0304, P0305, P0306, P0307
P0303 - randon misfires detected
P0174 - lean bank 2
P1313 - misfire rate excess emissions (probably causing the newly joined "Restricted Performance")
P1316 - misfire rate excess emissions
P0430 - catalyst system efficiency below threshold bank 2
P0193 - Fuel rail pressure sensor A circuit high

With the exception of number 1 and 8, the entire engine is misfiring lol.
Don't necessarily feel that as the car continues to go down the road but there is no indicator to state when each misfire might be happening.
Let's start there I guess and see if we can backtrack this into a potential root cause.
That's a lot of misfiring.

 

I think the first thing to address are the vacuum leaks. They will almost always be at the root of so many misfires and lean codes. A flaky MAF can also cause lean conditions.

 

Took your advice and decided to try a new (used) MAF.
Cleared up all but one code which is P0430
I decided to buy a used Denso unit off ebay in case it did not resolve the issue and I have chased my tail in past with flaky aftermarket sensors.
I knew that I had a small air leak around one of the cam covers but not nearly enough to trigger all of these codes. I have had far worse air leaks in the past with this car.
So thank you for the suggestion - it worked out good.
Now I need to chase down P0430. I remember swapping out the O2 sensors on bank 1 but I do not remember ever doing it for bank2. Might be something to follow up
Next, I will correct that cam cover leak to make sure I do not circle an obvious problem as small as this one is.

 

You have a bad cat on that side of the car. Changing O2 sensors won't fix that. It's bank 2 which is the left side of the engine when sitting in the drivers seat. Last I checked (if you can still get one from Jaguar) they were over $2000 each! Davico makes a lot of after market cats and might be worth a look?
After Market Cats

Here is the list of what they have for the S-Type and it looks like they have what you want?
S-Type Cats

If miss fires are not fixed the excess fuel will destroy the cats. It just depends on how much extra fuel is jammed into the cars. I had an injector failure cause the same thing on my 2014 XJ. I fought it for several months with various things but I had to replace the cat in the end to fix it permanently.

Good progress with the other codes!
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startup chatter is a broken park pin in the VVT unit making it bang against the stop until oil pressure rises.

 

Certainly not unrealistic that this will end up being the issue.
I drove it for quite a while with the CEL on, not knowing that codes were stacking up in there.
Originally my CEL was for lean conditions and since I figured it was all air leak related, I just didn't give it much bother.
I checked out the links provided and as expected, they are somewhat precious in the pricing. They are on ebay as well (same company) and they are 450 or something like that. Will circle back to this thread was I decide on the ultimate path to fixing this - cats and all considered.

 

10 years on this forum and have never heard of this as a diagnosis.
Obviously, I am really interested in understanding more.
Is this a job you performed or do you have any pics, links etc?
I will do a search here myself to see what pops up but really interested in this diagnosis as I am sure many others are as well.

 

razorboy xalty is one of our top Jaguar mechanics on the forum and I will bet he has done that repair multiple times. Waiting to hear what he has to say and I also have not heard of that failure but I have little experience with the VVT's.

One problem I was never clear on is will the after market cats allow the car to pass inspection? The sport cats I investigated did not and required a tune to disable the check engine light. One reason the aftermarket ones are cheaper is they will not last as long or work as well as the OEM ones. I ended up getting a used OEM one with 45K miles on it and after another 1000 or so miles all is well. One thing I found interesting and was very glad to hear is the cats are all the same for the 5.0L and 3.0L engines. Even my XJR uses the standard cats so Jaguar made the exhaust system plenty big.

I have researched Davico and they seem to be a leader in after market cats with a large catalog of applications but don't know anyone who has purchased or used that brand on a Jaguar. One thing that was interesting to me is they are actively expanding their catalog. When I was shopping for some reason they had the passenger side cat setup but not the drivers side for my car. I contacted them and they said they had never had a factory part to copy but if I was interested and would send them my bad drivers side cat assembly they would copy it and place it in the catalog. I did not and went used instead BUT I just checked and they now offer both sides for my 2014 XJ.

One of the wilder repairs I saw on this forum was a guy who cut the cat open removed the brick inside and found a replacement brick on-line from China. Then installed the replacement brick and re-welded the cat back up! Claimed it worked and passed inspection too.
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