which cylinder is it?
 

My engine (4.0 in a 1999 VDP) started missing and I'm pulling codes p0303 and p1316. According to Jaguar DTC the P0303 code is a misfire on cylinder A3. Further Jaguar references also call this cylinder 5. So, are cylinder 5 and A3 the same? How do I physically pinpoint that cylinder? I suspect that I have a bad coil. Any assistance in pinpointing the cylinder would be appreciated.

Thanks

Larry

The DTC P0303 for 1999 XJ model with A26 and A27 engine shows Cylinder A3 which is Cylinder 3.

P0303 Misfire detected – cylinder A3 (3)

Bank A is equalivent of Bank 1.

There is confusion on Bank1 and Bank2 location on the engine - you look at the diagram below:

Here is a firing order diagram that shows bank 1 (Bank A) is on the left side of the engine viewed from the front of the vehicle (on US models it is passenger side).


https://www.jaguarforums.com/forum/a...ine=1371951686

__[ US models Bank 1 is passenger side)._________[ Firing order
__[ Firing order 1 : 5 : 4 : 2 : 6 : 3 : 7 : 8_________[ (Bank)-Cylinder (1)-1 : (2)-2 : (1)-7 : (1)-3 : (2)-4 : (1)-5 : (2)-6 : (2)-8


Cylinder 5 misfire would be P305 DTC and would be bank 2 (Bank B) - B1 is cylinder 5.


Jim Lombardi

Thanks Jim - this is perfect.

Just to mention that the left diagram is for our X308 engines, the right one is for the ones after. In the UK,where the car is made and the technical books are written, 2002.5 MY is the timing for the 4,2 V8 engines.
Staying in the car, Bank A is the right one, Bank B is the left one, plugs are counted front to rear.

which cylinder
 

Try swapping the coil you think has the problem, with another coil on the same bank.

I swapped coils and the trouble did not follow the coil so now I am thinking injector. Any thoughts?

misfire
 

I would pull the plug next, ( when were they last changed)?
Do a compression test while in there; pull fuse for fuel pump, and use wide open throttle.
Next check the electrical connections to injectors.

Thanks again - while I was swapping coils, I also changed all the plugs. I should have tried the compression check at that time - I guess I was so sure it was going to be the coil that I didn't think it through. The old plug on the suspect cylinder was pretty oil fouled and burned, although all the plugs were ready for a change. I did drive 6 miles after the new plugs were in and I pulled the suspect cylinder plug and it looked like new.

Problem Solved
 

The problem ended up being the #3 fuel injector. I had to order the FI and it took a bit to get it. Interestingly, the injector was firing; I visually verified it and could hear the ticking through a stethoscope, so I was doubtful, yet replacing it did solve the problem. The lower o-ring was very deteriorated/cracked with pieces missing. Moral of the story is that you can't just go by the sound and assume it is working.

Finally, does anyone know if o-ring kits for the injrctors are available?

Thanks to everyone that offered assistance.

Larry

which cylinder
 

I think that most bosch injectors have the same o rings, unlike some nasty companies like toyota, who deliberately make them an odd size which are only available from the dealer. You should be able to get them from your local parts shop.

fredd60:

The injectors are Denso - do you think the same applies to them?

since my jaguar is american, I would be looking at the left diagram? Bank 1, 2nd from the front? code is P0302. Just double checking im a novice mechanic. I am trying to swap coils to see if it follows.

Richard,

If your car is a 4.0L V8 then the left diagram is the correct one.

I actually ended up taping a strip of the green masking tape that "sticks to almost anything" on each of my coil covers and writing the cylinder number for each on the strip.

Over my years of ownership I have had 3 coils go out, and always when I was in the midst of a trip. After getting royally taken advantage of by a Jag dealer (who didn't end up fixing the actual issue, I might add) I was determined that I would be able to do so myself if it occurred again. One OBD-II reader, a box with spare ignition coils, and a few tools later I was prepared. I changed both of the two failures after the first at roadside in less than 20 minutes from start to finish.

Autozone wants 113 for the coil. I am going to attempt swapping it to see if it follows the coil before I buy one. Wish me luck and if you know where I can order a cheaper one from the internet, please let me know. I dont use ebay.

You can find both OEM (Denso) and aftermarket (Beck-Arnley, among others) ignition coils for these engines for quite a bit less than $113, including shipping. Just use the web search engine of your choice on [1999 Jaguar 4.0 ignition coil].

Given the very spotty record of the Denso coils, I wouldn't be particularly hesitant to try an aftermarket coil from one of the well-known aftermarket parts companies.