Hopefully somebody can put me on the right track. I have had my 2000 XK8 for about 6 years and have had my share of issues with restricted performance. Decided to change the plugs to see if that would get rid of the problem and tried my best to follow the video that is posted here. I have changed spark plugs numerous times before on my other cars but never on a Jag. I removed the negative lead as per my JTIS manual and proceeded.

I got them all replaced and when I fired up the engine after hooking the battery lead backup, it started but then stalled. I can restart the engine and it sounds great as it does but immediately starts to stumble and then stalls.

Everything seemed to go smoothly when I was changing the plugs so what have I done wrong?

 

Rich, you need to plug an OBDII code reader in and read the fault codes. Otherwise, it is just guesswork. Post them here and we will help.

If any of the plug wells were filled with oil that is a possible clue as to a valve cover leak.

Also which plugs did you use?

Did you make sure all connectors on the coils were well re-seated?

 

I have a couple of code readers and I will have a look tonight when I get home and post as soon as possible. There was some oil in the some of the tubes when I pulled the old plugs, but not full, more like a tiny bit.

The plugs were the platinum variety recommended by my local parts store and I will provide details on them as well.

As for the connectors on the coils, I didn't remove any of the electrical connectors. There was enough slack so that I could just pull the coils out of the tubes and shift them out of the way while I removed and replaced the spark plugs. There didn't seem to be any way to ensure the coils and spark plugs were seated together other than just putting the parts back together and bolting them in place.

 

Did you undo the MAF sensor connector when removing the air intake?

 

Okay, here's what I have to report:

1) I didn't disconnect anything electrical other than the negative lead to the battery. I checked the best I could and all the parts I moved to get at the plugs on the passenger side of the engine were replaced the way they were and there are no obvious issues connections wise.

2) Just read the codes and they are now showing P1646, P0305, P1314 and P1000.

3) The new plugs are Bosch Platinum Plus 4002 which replaced the old NGK PFR5G 13E

I really would like to know the cylinder map for this V8 because cylinder 5 is referenced in the one code but all I can find is Bank 1 & 2, cylinders 1 to 4 ---- very confusing

Thanks for your help on this, much appreciated.

 

The drawing on the left is your car:

https://www.jaguarforums.com/forum/a...linder-ids-jpg

Try swapping coil number 5 with number 6 and see if the fault follows the coil after starting it again.

 

I will give that a try and thanks for the cylinder map. Very clear to me now.

When I replaced the coils there wasn't any satisfying "click" or other feel to know that it was making the correct contact with the spark plugs like there is with a traditonal single coil and wire setup. Just dropped them in the tubes and tightened up the 2 bolts. Is that correct?

 

It is better to spread a bit of dielectric grease on the inside of the boot, drop them in, then push on the top of the coil to fully seat against the mounting boss. The screws go on after that. Drawing them down using the screws is not as reliable.

 

If all this diagnostic stuff doesn't work out, I'd like to go back to the plugs themselves. Of late, I've grown disappointed in Bosch (don't ever use the Quads for ANYTHING!). If I can find NGK or ND plugs I'll always use them before Bosch. And for a late model "blown" engine I've found that using Iridium plugs HAS made a difference in how the car ran. Actually, a few years ago Champion had a sweet deal on its Iridiums. Put'em in a Northstar - never had a hiccup. And having maligned Bosch as badly as I have, I must confess: I put a set of their Iridiums in the XKR 15,000 miles ago - no problems. In this case, the Bosch were the only ones immediately available.

In any case, GOOD LUCK!

 

Okay, status update:

1 - I tried firing up the engine and all it did was crank over. Didn't catch or start at all.

2 - I moved #5 COP to #6 and vice versa

3- I took all the COPs off and put the dielectric grease on the inner boot and then reseated them and bolted them down. I don't know about your Jag but this one does not "seat" the COPs in any satisfying sens e of the word. Push them down until they stop and wiggle them as much as they allow and then screw in the bolts. There's nothing more that can be done.

4 - Turned the key and nothing different. Cranks but no catch.

5 - Hooked up the netbook to the OBDII and cleared the codes. No difference.

6 - Took all the new Bosch plugs out and put back the old NGKs.

7 - Engine cranks and seems to want to catch but doesn't. Almost like it's flooded.

Anybody have any ideas?

 

After all the cranking without starting it is possible that you are suffering bore wash now. Check the compression just to be certain. That's assuming you have fuel pressure.

 

Check for a strong squirt of fuel at the Schrader valve on the fuel rail after cranking. There is a chance your fuel pump coincidently died.

If you have fuel, follow the bore wash resolution procedure documented in many places on the forum.

 

Not sure what you have going on but look at this no start procedure.

Link JagRepair.com - Jaguar Repair Information Resource

PS Bosch plugs are just fine in that car i have them in both of my cars!

 

As others have suggested, it sound like the starting and stopping that has been done whilst carrying out fault finding on your original issue has caused flooding / bore wash, so that needs to be addressed first.

In the original post you stated that you didn't remove any electrical connections, which may be part of your problem. Disconnecting the connectors would prevent any tension / snagging of cables. It also allows an opportunity to give them a squirt with contact cleaner when putting them back.

To get access to one bank of plugs you would have needed to remove / move the air intake duct - how did you do that without removing or putting strain on the MAF connector ? When you remove the spark plugs and put a bit of oil down each bore to cure the non-start issue, I suggest that you unplug and clean the connectors as you go. Also make sure you give the ignition coil tubes a clean, and squirt contact cleaner up inside the tube where the contact spring is located.

If the only thing you did was replace the spark plugs initially, I would bet on a disturbed connection somewhere for sure. Don't worry, follow the procedure to get over teh bore wash and clean re-plug the connections and I am sure it will all be OK.

 

Brittle plastic on the COP and the wiring connector could have been damaged during the required removal. I had a COP crack after my first plug change, and misfired off and on until i found it eventually.

 

Thanks to all for their suggestions and I am not giving up yet.

I am attaching some pictures so that you can see what I have been up to.

All the new Bosch plugs were pulled and the old NGKs put back in and I have attached a picture showing them side by side for comparison.

I have more pics but I don't know if they would be helpful.

Moving the breather is easy and didn't appear to put any strain on anything. I did disconnect all the COPs and examined the connectors and they looked clean and trouble-free to me. I did not spray them with contact cleaner however.

I will try the procedures suggested once I read them all and get some more time to work on her, but thanks again to all.

 

Others have already mentioned this but I thought I would also after seeing your pic #2.

In that pic, it clearly shows that you did disconnect the plug from the MAF sensor which is mounted in the air intake. This is normal as you would not be able to move it out of the way without doing so.

Because you said that "I didn't disconnect anything electrical other than the negative lead to the battery", is it possible that upon reassembly you forgot to reconnect the MAF sensor?

That could easily cause problems & stalling.

 

When you start the car the fuel pump is powered by the key power then after the start the fuel pump is powered by constant power in short this means 2 fuses and 1 relay. It could be that one of your fuses is blown. One way to find out is for you to take a fuel pressure reading at the fuel real. You could also have the cylinder washing but I would check the fuel pressure first cylinder washing would not let you start from the onset not stall after a good start.

Link JagRepair.com - Jaguar Repair Information Resource

This information was in the first link I provided.

 

I may have removed a connector and forgotten that I did... not getting any younger you know. I am attaching a couple more pics of that side of the engine and maybe you could tell me exactly what you're seeing as I am not sure which part is the MAF?

And I know I could look this up but does anyone have a link handy to a procedure on checking the fuel pressure? Oops, just saw Gus already provided that in his post above. Thanks!

Thanks much guys.

 

In picture #2, the MAF is the piece between the airbox and the "tube" coming over from the throttle body. It looks connected in picture #3 if that is your current state.

But it won't hurt to recheck the connector and shoot a spritz of cleaner on it, just in case.