I have posted several problems on here looking for advice about misfires, can someone help me? I have replaced all 8 coil packs on my XJ8 and now I am getting the same misfires again. Is there something else that causes this? The spark plugs look good. The car has around 82,000 miles on it. I can change the coil packs that are reading misfires, and after a day or so, I will get a code with 2 more misfiring. Please help!!

 

off the top of my head, it could be a fueling problem or the timing.

 

Clogged injectors!

 

Is the misfire codes showing up on the same cylinders each time or on all? What misfire codes are being set? Any other codes? Most auto parts stores will read you codes for free.

EDIT:

I went back and read your previous posts from November. What has been happening since then?

Let's start over with the specific codes.

I'm just over the mountain in Ellijay.

 

I have had all cylinders give a misfire code, fron P0301 to P0308. Each time it threw a code, I changed the coil packs. Every time I get the misfire code for the cylinder, I get P0300, random misfires. I also get P1316, misfire rate exceeds emissions, and P1000, obd readiness systems test not complete. I have noticed that each time a code for two cylinders comes up and I replace them, two more come up in a day or so. They are always on opposite cylinders.

 

Have you changed your plugs? If so have you checked the wiring to the coil packs for any cuts or open wires? Have you checked your fuel pressure?

You could have fuel contamination or you may need to add a fuel additive. BG 44k is about the best I have found and you may want to try it. If all is ok then you may want to check your compression to see if you have a more serious problem.

My suggestion to you would be to begin with the plugs and go down the list.

 

Would all 8 plugs be bad? I have had codes on all 8 cylinders? I looked at all of the plugs and they look to have been changed before I bought the car. Would fuel pressure cause random cylinders to misfire?

 

Gus outlines the issues that are listed on the diagnostic code causes list. Since you have replaced all the coil packs time to start looking for something that would affect all cylinders.

Check fuel pressure at the valve behind the 'A' bank valve cover. Should be 41 psi or slightly above.

Do a compression test. While the plugs are out and at 80k+ miles a new set of plugs might be a reasonable investment.

Since you have been chasing this issue for a couple months I assume that you have run a few tanks of gas through it. Fuel contamination is also listed. Was the 60k mile fuel filter change done or are you running on the factory installed one? Been buying gas at a low volume station?

Since your knowledge of the history of the car is limited I would throw in a cleaning of the MAFS and the throttle body.

Guess I just seconded what Gus had already outlined but these are the things Jaguar lists as causes of the misfires.

At least you have a complete new set of coil packs.

 

with misfires that throw a 1316 code for severe misfires to cause cat damage, you should have changed the plugs for fouling. and at 82k youre not saving money waiting till 100k recommended change interval. have a onboard fuel injection system cleaning done before, clean throttle body and part load orifice. Then change the plugs and go from this point on diag if you continue to have issues

 

The fuel injection cleaning you mentioned is done at the dealer? Also, what spark plug is recommended? I want to fix this problem so I can drive the car again. I am afraid to drive it with the 1316 code.

 

while others do onboard fuel injection service other than the dealer. A woman friend of mine with an 05 str had her oil changed at another shop, they broke 1 of the under tray brackets, left 3 bolts out and tie strapped it. Then proceeded to check her air filter and broke her air filter box($400 for the assembly) all because they dont work on jaguars and dont know what theyre doing. So if you dont go to the dealer, at least go to someone who knows what theyre doing, your car is pretty easy to flush injector. Pull fuel pump relay and hook up cleaner apperatus and run till it shuts off.

 

Georgia -- Sounds like you have plenty to go on for now. Hopefully the suggestions offered so far will help to determine and correct the problem. If so, please let us know what the problem was and/or what cured the misfire.

Out of curiosity, were you able to correct the battery drain issues you reported a couple of months ago with a new battery? If so, have you had any battery drain issues since then or have you checked the battery voltage recently? I had a similar occurrence shortly before i had a similar misfire. Not sure if related or not, but I am interested to see if there may be something more than coincidence here.

I believe NGK Iridium spark plugs were stock on your XJ8. I'm sure you can locate the part number somewhere on this forum. Also, I'm sending you a pm with some info that may be of use for you.

 

Thanks to everyone. I am working on cleaning the fuel injection now and will post results later this weekend. As far as the battery drain, the new battery cured the problem. I am still working also with the transmission fault when I move the gear selector into manual mode. Someone posted to adjust the cable. Is this the correct thing to do for this problem? If so, does anyone have a write up on how to adjust it? Thanks again to everyone who has responded with help. I really appreciate it.

 

OK. Update to post. I did the fuel injection cleaning and part load orifice tube cleaning. I cleared the codes, started the car and..... no miss, until the rpm's went below 1000 for regular idle. At that point, I still feel at least 2 cylinders missing. I have not driven it enough to throw another code, but I can still feel the engine missing. Any more ideas?

 

I know we have talked all around it but did you change the sparkplugs? Have you done a compression test?

 

Next step is change the plugs and check compression. I am unsure of the compression test, as the misfire moves around cylinder to cylinder. If I had a definite problem with compression, wouldn't it be limited to certain cylinders? Not jump around different cylinders.

 

In cleaning the fuel system did you start at the filter? Doesn't sound like the prob since your miss is below 1K but my threw an 1136 and despite low miles my filter had soup in it.

 

Now that the injectors are clean I would replace the plugs to ensure that they are not part of the problem. I would also add a quality fuel cleaner and drive a little and see if it levels out.

When this all started did you clean the throttle body and did you check the fuel pressure? When was the fuel filter replaced? The last question is how about your chain tensioners, do you know if they were rattling or lose? You say it seems to be inconsistent misfire and all of this is related to the correct timing of all of it together. A compression test could identify the problem but I am not sure. What do you think?

 

so its been 2 years, but did you find a cure? because i have a 2000 XK8 that is having the SAME EXACT issues, and i dont know where to start. please email me L e p p a r d 0 7 2 9 @ g m a i l . c o m. thanks

 

Hi I have had the same problem with my 2000 jaguar xj8 170k on it. If you're getting multiple misfires it is most likely the ignition control module.