I think it is a Nikasil engine. Built date is January 2000

 

Yes, I used ground stud in the left engine compartment that's listed as being connected to the coil grounds

 

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I would like you to test the presence of spark control to the 3 cylinders you have codes on. You can do this with the spark tester we talked about. Make sure you test and monitor as the engine is running.

Link

 

Hi Gus, Yes, I did this test last week. That's when I realized that I was getting spark on all 8 cylinders. I had decided to do the test on all cylinders to make sure I wasn't getting wrong info from my codes. I plugged the spark tester onto the spark plug and then to the coil. Started the engine and observed spark. I did it for all cylinders and observed spark on all of them.

Using my stethoscope, I checked all of the fuel injectors and they were all ticking. Fuel pressure was showing 40psi with key on. I did not do a fuel pressure test with the car running.

 

OK! Now we know that all coilspacks are doing what they are supposed to do. As for the injectors they are working and if I recall you said that you replaced them with new ones.

For the car to run properly you need spark, fuel and compression and it looks like you have tested 2 out of 3 so the next thing is to do a compression test on all cylinders and document the readings. This is how you do it.

Link https://www.popularmechanics.com/car...%20revolutions.

 

I'll do a compression test tomorrow. Any thought on if a bad camshaft position sensor could be at fault? I get no codes for this, but the thought crossed my mind.

 

You are getting spark on all cylinders so for now I am not concerned with the cam shaft sensor. A compression problem could be any of the following, Nikasil block, valve, failed compression ring or the cam shaft. Do the compression test first. It could be that we overlooked something.

Have you ever added Restore to the engine oil? If the block is Nikasil we can talk about it after the compression test.

 

I did the compression test this morning.
Cylinder Reading
1 ..........126
2 ..........128
3 ..........123
4.......... 128
5 ..........119
6 ..........124
7.......... 121
8 ..........125

 

They look a little low to me but I will check to see the specifications for the car. I do not recall what it should be. I did notice #3,5&7 were much lower.

What viscosity oil are you using and have you ever added Restore to your oil?

Gus
JagRepair.com - Jaguar Repair Information Resource

 

I have been using Mobil 1, 5w-30 changed yearly. The car used to get driven around 3,000 miles per year. I have never used restore. I have always been reluctant to use additives with the exception of
BG44 and Techron. When the car was running well I never thought about it. Since it has had this problem, I never run it longer than maybe 2 minutes because of my fear of catalytic converter problems.

 

I have been using Mobil 1 10w30 in my 99 xk8 ever since I got it and I have 143,000mi on it and no usage of oil. BG44k is about the best product to use for carbon buildup and cleaning the injectors. As for Restore it is not a placebo when it comes to restoring compression on Nikasil engines. If it was I would NEVER recommend it!

Ok! From what I can find the cylinder compression should be around 150/160psi and you are getting a range of 128 down to 121. This could be caused by compression rings or carbon on the valves. I would suggest testing again but first add a tea spoon of oil on each cylinder that you are testing and see if you get different results. If the compression increases then the piston compression is in question if you see no suitable increase then carbon on the valves are in question or maybe both we will see.

Note - Because you added oil to the cylinders you WILL have a plume of blue smoke coming out of your exhaust when you go to start the car. Be sure you let everyone know because they will think your house or garage is on fire and you will soon see fire trucks at your house.
I am still checking on the compression range because I have not found anything that was Jaguar 4.0 specific so please be patient with me.

 

I found it!!

 

Funny, I did a compression test a few years ago when this problem started, but I was unable to find out if my numbers were ok or low. I'll check it with the oil tomorrow. I have used BG44 in this car and my others in the past. Usually I use Techron.

 

Here are the readings with oil


.............old............ new
1 ..........126...........134
2 ..........128...........133
3 ..........123...........139
4.......... 128...........131
5 ..........119...........133
6 ..........124...........135
7.......... 121...........129
8 ..........125............132

 

Well my best guess from here is that you are suffering from cylinder washing as many have had. I will recommend that you close everything up get an oil change to 10w-30 and add Restore for 8 cylinder. Start the car and let it run to full operating temperature and do that for a few days then clear your codes and see if they come back. I will standing by!

This is a link about Nikasil JagRepair.com - Jaguar Repair Information Resource

This is another link about Nikasil and Sulfur JagRepair.com - Jaguar Repair Information Resource

 

Hi Gus, I was afraid of that but was thinking the same. I'll do the oil change and restore. I'll keep you and everyone posted.

 

First I'd like to thank Gus and michaelh for trying so hard to help me with this problem. I did an oil change and added Restore. I have run the car up to temperature for 3 days and it still runs poorly and after erasing all codes, the same ones come back. At this point I feel like I have two choices. Either I give up and get rid of the car, or I put another engine in it. The car was purchased in 2014 and was in bad shape. I have put a lot of time and work into it. When it ran, my wife and I enjoyed it very much. Right now, I"m thinking of replacing the engine. If I do, I'll start another thread with questions about that process. I'll take a little time to figure it all out. I do love the car and have done so much to it, I don't want to let it go. I'll attach some pictures of some of the work done on the car and there is more than this. It was a lot

 

Not what I expected to hear. Back to figuring this out..

Gus
JagRepair.com - Jaguar Repair Information Resource

 

If it's any consolation I feel your pain as I had to replace the engine in my '97 XK8 last fall. The good news is that there seems to be plenty of used and rebuilt engines in the States. Unfortunately for me no one would ship to Canada. When I finally got one shipped here from Canada I had my mechanic do the install and all is well with the car again.