I am continuing the never ending quest to get my 2003 XJR fixed and not throw codes. One of the symptoms besides all the DTC codes is a relatively loud clicking from the rear of the valve covers on both banks when cold. The car starts up fine and the sound is very faint. It's gets rather noticeable once the gear shift is moved into drive or reverse. It is not terribly noticeable when the engine is rev'd up a bit and after the car warms the sound goes away; or is very faint when idling. The car runs extremely well apart from the DTC codes. At this point I wonder if it has one or two broken valve springs causing this clacking? If so, can these be replaced without removing the heads? I have searched the forum but cannot find a specific conversation about this subject.

Besides the noise, it throws the following codes, which popup a few miles after a DTC reset: P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P1316.
It had a P0400 code EGR valve code but I replaced the EGR valve which has stopped that one from happening.
I checked the fuel trims which are a bit high at this point and it occasionally throws the P0171 and P0174 codes; I suspect since the trims are high. And lastly, it just threw a P0105 code ( MAP Sensor to ECM circuit fault; MAP sensor failure.) after I replaced the EGE valve.

Any advice from this august body would be appreciated!
Best, Dave

 

Should be able to do so.

Basically, fill cylinder with 100psi of compressed air or use a nylon rope and stuff it in the cylinder to prevent valve from dropping.

Remove cam and bucket, compress spring, remove keepers and retainer. Reverse to install.

I somehow doubt you have a broken spring though.

 

it could be a number of things not necessarily valves, in my case loud clacking was caused by loose ignition coil
did you check if map is plugged correctly and wires intact?
as for this beautiful set of misfire codes, maybe camshaft or crankshaft position sensors are tired and failing intermittently

 

If you’re willing to go to the extent of replacing valve springs, I would **HIGHLY** recommend removing both cylinder heads and have a valve job done professionally at a machine shop. Honestly, it’s not that much more work since you’ll have the front of the engine torn apart and having to pull the cams anyways. This way you tell them your concerns and tell them to check your valve clearances prior to dismantling to see if they’re too loose. I will say this though.... cylinders #4 & #8 on the intake valves are the last to receive oil on a cold startup. It’s possible that there’s excessive valve clearance there due to that. Just another thing to think about.... do the oil filters you use have an anti-drain back valve in them? I think most do but, just an idea.

 

Good idea to have the heads removed and repaired but at this point, I will try whatever gets it fixed without too much more trouble and expense. I have had this car for ten months and spent a great deal of time and money on it. I'm thinking of at least trying to clear the fuel trim problem and then seeing what the codes read.
I use Bosch oil filters and 10-40 winter and 20-50 summer for all my XJ cars here in the Georgia.

 

I have swapped the coils from one of my other cars with this one and no difference. I did remove and clean the MAP sensor as well though the connector was clean; as with most all JAG connectors with the rubber gasket. You may be correct; it could be those sensors but I'd think I'd get some code if they were bad.
Perhaps I should change them just for the heck of it....I've already fooled with so many other things these changes are relatively easy...

 

If you have rich condition, be it cause of misfire or not, you may have bad fuel pressure regulator or dirty injectors, check fuel pressure and for presence of petrol smell at fpr vacuum line. injectors dunno how to test, i learnt to recon symptoms and if dirty just send for cleaning.
my coil simply pulled its screw sockets from valve cover plastic body and was rattling in tact of ignition, sounded like very bad valve, you could try to more or less exact pinpoint the place where yours comes from with stethoscope, but probably you gonna have to strip things a bit anyway to find out
on second thought sensors are not likely cause of you problems, i would dig elsewhere first

 

20w50 is really thick. I recall spec being 5w30. I run a 5w40 year round.
Too thick is just as bad as too thin so i would really reconsider this viscosity

 

If changing the oil will fix the car issues I'll try it! Perhaps I'll drop down the viscosity on the next oil changes....Thanks,

 

I'd be amazed if oil that thick was getting into the tappets properly, which would stop the valves opening properly, cause your noise & create misfires as the cylinders can't breathe correctly.

 

I have seen a crank sensor fault cause those codes on these cars.

 

warmed up makes no difference. cold 5w30 is way thicker than 20w50 at operating temp.

these never make any noise from the valvetrain. if yes there’s something wrong

 

That is some good advice guys. I do have a new crank shaft sensor on hand, a box of 5-30 oil, and extra Bosch oil filters. I'll just do all of those tasks at the same time; but not before maybe late next week or the following week. Thanks a bunch!