Was very pleased my 04 XJ8 had finally read P1111.
My birthday was very soon, so it would pass the emission inspection for 2026.
Went to leave a few days later, & it had a bad miss, the check engine lite came on.
Codes P300, P301-P308, P316, P171, & 174.
Misses on all cylinders, lean both banks, W T F happened.
Having chased the 171& 174 codes before, replacing parts.
Until the 8 intake manifold gaskets finally fixed things.
Weird thing was when the motor came up to temperature.
Clear the codes, & drive around all day with P1000 the only code
Fuel pressure was at 55, so were the fuel injectors delivering enough fuel at cold start up?
Tried some replacements, result was no better.
Then an awful knocking noise developed, at cold start up.
VVT solenoid sounded to be the issue, & was replaced.
Noise was much less, went away quicker, but still there until warmed up.
Am at a loss where to look next, any ideas would be appreciated

 

Could the replacement solenoid also be bad or sticking?Maybe worth trying another one?

 

@Wingrider I have been giving some thought to your issues and I remembered previously reading an explanation by @XJ8JR that described a similar issue, that may or may not be related to yours:

"I've had this issue for 2 years now. If the car has been sitting for more than a few hours, I'll get a loud clatter for literally just 1 second. I've tried every weight of oil and every type of filter, but nothing has helped. After hours and hours of research, I came to the conclusion that it's a VVT issue.

Apparently, many engines with Variable Valve Timing develop this racket. It's common across all the brands, not just Jaguar. What happens is there's a little locking pin that holds the VVT gear or whatever it is in place when the engine shuts off. For whatever reason, this pin decides it doesn't want to lock in place any more, so that when you start the engine, the VVT gear goes nuts for second, which creates the rattle. If the oil hasn't drained out of the area yet, it won't make the noise. That's why it only occurs after the car has been sitting for a while.

Supposedly it is just noise and does not cause any additional wear or harm to the engine, unless it continues on for more than a second or two. It is fixable, but you would need to perform a bit of surgery on the engine to be able to replace the VVT gear."


"Here is the thread in its entirety. Maybe this will help?

Good luck!

 

Also, if the VVT is malfunctioning it is plausible that it could cause multiple misfires, but seems unlikely that both banks would suffer failure at the same time.

 

At the risk of being a hammer in search of a nail, those were the same symptoms of my throttle body developing a leak at the butterfly spring/pivot (also a '04). Ran significantly better when up to temp, but misfires etc. when cold, etc.

Have you done a smoke test? The spraying starter fluid or other combustable fluid wasn't effective in finding the leak at the throttle body, but with the smoke test it was obvious once I knew where to look.

 

Ahhh the good ol' "VVT rattle". My 245k mile Land Rover LR3 does it as well as my 152k mile XJR. From all the research I've done on the issue, it's simply just an annoying noise, and while in theory, metal fatigue could eventually cause the gear to break internally over time, I've yet to see any sort of report or thread of an engine failure that resulted from the cam gear getting destroyed internally and jumping time. That's across the S-Type, XJ X350, and Land Rover LR3/Disco 3 forums that I've searched.

From what I'm reading of Wingrider's description though, they say that the noise was present until the engine warmed up, which would rule out the VVT rattle as that will stop making noise in a matter of seconds once the oil pressure builds up in the gear.

 

Friend of mine, who is a mechanic, suspects a bad oil pump.
Or a faulty VVT solenoid from the parts store.
Need to check oil pressure, to eliminate the pump being bad.
Question with the oil pressure sensor removed.
Replacing it with a fitting, so an oil gauge can be attached.
Will the motor still start,& run???
If not where else can i pick up the oil pressure?

 

You should be able to run an oil pressure gauge in line with the factory sensor. I’m not sure how engine management would cope with not receiving oil pressure data. You would need to just use a t-fitting for your gauge and attach the factory sensor to one side of the T and connect the other side of the T to the bung on the engine side.

Is the thought that the lifters or solenoids aren’t receiving enough pressure for the valves to fully open or causing the timing to be incorrect, leading to misfires?

The fact that the misfires occur on both banks leads me to suspect it is something systemic, like low oil pressure caused by a bad pump or pressure loss through a leaky solenoid (if that’s even possible).

 

Thats our belief Jacuar, not enough oil presser;
Have all the pieces, that you mentioned, to include the sensor
The oil pressure gauge should tell the pumps condition.
Will hire my mechanic friend to change the pump, if need be.
At another friends shop who has a lift.

 

Well wrong again oil pressure was @ 80 lb's
Car will run without the oil sensor being connected.
Not enough room for everything fit & connect.
Today the noise quitted down, then back up W T F.
Still misses at cold start up, then smooths out @ runs fine.
Still runs lean on both banks though
Wondering if the new VVT solenoid i installed is defective.
Noise seems to originate from there

 

Is it worth swapping the VVT from one bank to the other to see if the noise shifts banks?

 

Will just exchange it for another one.
Bad enough doing the job over.
Let alone taking the other side apart.
Way more parts to remove, getting to the valve cover.
May pay more to buy at the parts store.
But any exchanges, will go a lot faster.
Noise level will go down to a normal level.
Then back up again, the stethoscope indicates.
That the VVT solenoid, as the noises source.
Rest of valve train sounds, seem to be normal,
Appreciate the assistance from everyone

 

Well the second solenoid shows vacuumed is now reading normal, instead of 7".
The misses are fewer at start up, but lean on both banks with restricted performance.
Will now occur almost immediately, when before the misses came up first & fast.
Just like this does now, fast & first, when it took a while before the lean banks happened.
Plus the restricted performance lite, took much longer to lite up, than now.
Another one to remove & return, really getting tired of this
Bit the Bullitt & ordered one from the dealer, list is $300, hope this solves the issue.
Tried to order one from Ford, for a 2004 Thunderbird, no longer available, W T F???
Was told they have some real problems acquiring some parts for these cars.
Are these solenoids that different or special ?

 

Good that you narrowed down the problem but its disappointing that you have to replace a new part again. The quality of new parts has gone way down regardless of what brand you get.