Symptoms: Rough idle,Misfire, and Sputter at 45-55mph and up most hills. Punch it and it seems to do fine. No CEL until recently; flashing CEL and one solid afterwards. P0303 (misfire cylinder3) was the code.

Diagnosis: Pulled coil cover (passenger side) and found oil in the wells, fouled plugs and the tips of the coils also had oil on them.

What I ordered:

· The following from Auto Zone: Bosch Iridium Spark Plugs, Victor Reinz Valve Cover Gasket, air filter, fuel filter, anti seize, dielectric grease and some permatex to seal the joints.

· New coil packs (set of 8) from eBayfrom seller dependableautoparts

· 2 VVT Seals from RockAuto.com

FYI – I’m no mechanic, this is the biggest job I’ve ever done and I still have to do the driver’s side. As far as instructions go, I have a subscriptionto All Data.com, but I’ve also downloaded the JTIS & JEPC from this forum.

After putting it all back together I took a drive trying to recreate the symptoms – I sat in traffic, idle was perfect – punched it on the freeway, smooth, and no hesitation – went up a few hills, perfect. The car is now running better than when I bought it a year and a half ago. I will be keeping an eye on things, but so far everything is great. I was skeptical about the eBay packs, but so far so good! Next I will do the driver’s side, which up to this point hasn’t given me any issues.

The purpose of this post is to try and help people like myself, who aren't mechanics. I figure the content, item links and pictures may be able to help someone who is having similar issues, and want to do the work themselves. I know these symptoms are very common on these cars. Thanks for reading!

Below are some pictures from the project up to this point.



CAREFUL NOT TO BREAK ANY SCREWS!!

 

Very good job but it looks like you have more work to do??

You have the old plastic timing chain tensioners. They are orange/yellow in your engine. They started out white. I have circled them in red.

They need to be replaced with the upgraded metal ones ASAP. You will destroy your engine when they let go. And it's only a matter of time before they do.


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Yes, I agree, and I should have done them when I had the valve cover off. I knew someone would point that out.
I'm not sure if that's a job for me to do.... I don't like messing with the timing much, bad experience many years ago. I talked to a Jag mechanic (my guy) before getting started on this and asked him about these tensioners, as I wasn't sure what I was going to find and if they had been replaced or not. He basically told me to inspect, make sure the chain is tight, look for cracks, etc. and if everything looks okay not to worry about it. According to the service records that came with the car the chain was last serviced/inspected in 8/2010.

Again..... I agree, after what I've read, that these should be replaced with the new metal ones. I just want to fork out the labor to have it done at the moment and not sure if I can do the job myself.

 

Yes it is a big job and for us Shade tree guys I don't know if I would try it or not? There are several sets of very detailed instructions for replacing them. I would download them and do some reading.

Maybe you can change them yourself or maybe you will decide to trade cars? The 2003 and up S Types are very cheap.

This was one of the major factors why I only looked at the 4.2L engine. Of course the blower was also a plus!

The cracks/damages are very often not seen until the old tensioners are removed so they could be damaged now and you don't know it.

Now you can most likely avoid engine damage IF you listen closely to the engine at every start up. Things will begin to rattle and make noise when the tensioners are getting close to letting go. It's not 100% but more than a few people have caught it in time and then posted pretty torn up tensioners to show how close they came to the edge!
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