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I am new here, but am the delighted new owner of a 2004 XJ8 that I have been driving for a couple of weeks. While she's not 100% perfect at almost 103,000 miles, she drives like a dream and I truly couldn't be happier with my purchase.
The other night, completely out of the blue, the car developed a misfire when started. The misfire is noticeable at idle and when driving. And it wasn't long before the check engine light came on.
I scanned the ODB II system this afternoon and the results are as follows:
While there were some maintenance records that accompanied the vehicle, I do not see that the plugs and wire/coils were replaced previously.
I would like to ask the community to offer me some guidance as to how to address the situation in an orderly fashion so I can get the issue resolved and get back to driving her. Any feedback will be appreciated. Thank you.
Welcome to the Jaguar Forums! It's great to have you with us.
Typical causes of the P0300 misfire codes are problems with the spark plugs, ignition coils, a clogged fuel filter, a failing fuel pump, or contaminated fuel. You didn't happen to purchase fuel from a station you don't normally visit did you? And are you using at least 92 octane premium gasoline?
At 103K miles, your X350 is overdue for spark plugs, so put those on your list. The OE plugs are NGK Laser Iridium IFR5N10 (7866), which NGK rates for 80K-100K miles of service, but when I pulled ours at around 96K, they were well past their useful life, with visible erosion of the electrodes and expansion of the gaps. The 7866 is a relatively expensive plug, but you can save some $$ by ordering them from Rock Auto. A less expensive option is the BKR5EIX-11 (5464) with a nickel ground electrode, which NGK rates to perform even better than 7866, but to last only 40K-60K miles.
Another thing I would recommend is that you order two or three ignition coils because you're at the mileage where the original Densos seem to begin failing. The best deal I have found on coils is the Airtex 5C1420, just $31.79 each at Rock Auto. Airtex is an OEM for Ford and others, and the coils I have purchased so far are marked FoMoCo (Ford Motor Company), indicating that they are probably the coils Ford dealers install in Ford's versions of the Jaguar V-8 engine, and may even be the coils Jaguar dealers install now that the original Densos are no longer available. The reason I suggest ordering two or three coils is that your cylinder 4 and 5 coils may already be failing, and it's good to have a spare coil to keep in your trunk because there's no question you will need one eventually, probably when you're far from an auto parts store. Of course, if you want to spend the money to replace all eight coils now, that's an option too, but personally I'm just replacing the coils as they fail (three so far) and I have two spares in the trunk.
The cylinder numbering chart on the right applies to your car:
If you haven't replaced the fuel filter, then while you're ordering from Rock Auto, add a good quality filter such as Mann (a Jaguar OEM), Wix, Motorcraft, ACDelco, etc. They're only about $10 and easy to replace - you just have to remove the long plastic underbody cover on the left side of the car.
To help get you off on the right foot with your Jaguar, here are some important service and repair references:
I replaced the fuel filter on my 2005 4.2L at about 70k miles. She presently has 101k miles and is stuttering during hot restarts. A few jabs at the accelerator seems to clear it up. It occurs less frequently with premium Top Tier gas. No check engine light, yet. I suspect I'll replace the spark plugs. Some engine compartments are a pain. Is the x350 an easy DIY?
I replaced the fuel filter on my 2005 4.2L at about 70k miles. She presently has 101k miles and is stuttering during hot restarts. A few jabs at the accelerator seems to clear it up. It occurs less frequently with premium Top Tier gas. No check engine light, yet. I suspect I'll replace the spark plugs. Some engine compartments are a pain. Is the x350 an easy DIY?
Hi Sarks,
Replacing the spark plugs on the X350 is definitely a DIY job if you have the right tools and know a couple of secrets. There are several posts on the forum, some with photos. Some cars have a flap on the brake master cylinder housing that can be removed to allow easier access to the No. 8 coil and spark plug (rear right when facing the engine). Our XJR does not have the flap as far as I can tell, so I just twist the head of the coil until the angle on its mounting flange will clear the master cylinder housing with just a little rubbing of the ignition module and bending of the rubber boot. For the No. 8 plug, I use a 6-point 16mm spark plug socket, a 3-inch extension, a universal joint, and an 18 inch extension connected to the 3/8 inch ratchet. That setup allows me to get the socket and 3 inch extension on the plug, attach the flex joint with the 18 inch extension connected and angled forward where I can apply sufficient torque to the ratchet handle. Here's a photo of the setup I use:
The other potentially frustrating issue is removing the coil covers, which are secured with molded sockets that fit over short metal rods with spheres at their bases. The covers need to be pulled straight away from the cam cover, but there are things in the way like the oil dipstick tube, fuel lines, etc. Try to work your fingers behind the leading and trailing ends of the cover and pull straight out until the cover comes free. Then you have to snake it out from between the cam cover and the obstructions. I can't remember for sure, but I think I may have figured out that the Bank 1 cover (left side when facing the engine from the front) is easier to remove by snaking it back toward the firewall first, so try it both ways - moving it forward and rearward.
Regarding the stuttering during hot starts, you don't have a CEL, but you may have some diagnostic trouble codes (DTCs) stored, and most auto parts stores will scan the Powertrain (P) codes for free, they just can't typically scan the proprietary C (Chassis), B (Body) and U (Network) codes, but with any luck your codes, if any, will all be P's.
It could also be helpful to read your short-term and long-term fuel trims (STFT & LTFT) to see if the engine is running rich or lean, and to observe Live Data to watch the behavior of components like the engine coolant temperature sensor (ECTS), oxygen sensors (O2S or HO2S), etc.
It might also be worth having the fuel pressure tested both while idling and revving the engine, and after it is shutoff to see how the fuel pump and fuel pressure regulator are functioning.
And yes, it's time to change the spark plugs. I recommend using the OE NGK plugs (IFR5N10 / 7866) and before installation check and set the each plug to the correct gap, 1.0mm / 0.039 in. The proper torque for the plugs is 20 lb. ft. / 27 Nm.
Thanks Don. The MIL illuminated a couple of days ago. The OBD-II scan showed misfire from plugs 3,4,5. I'll replace the plugs and replace the fuel filter (my wife reminds me that I may have shortened the life of the fuel filter because I like to minimize the number of fuel stops).
Thanks Don. The MIL illuminated a couple of days ago. The OBD-II scan showed misfire from plugs 3,4,5. I'll replace the plugs and replace the fuel filter (my wife reminds me that I may have shortened the life of the fuel filter because I like to minimize the number of fuel stops).
Hi Sarks,
Were the diagnostic trouble codes P0303, P0304 and P0305? If so, the plugs are not the only possible suspects. Here's a snip from the page from the DTC Summaries Guide that defines the P0300 series of codes and gives possible causes:
You can download the DTC Summaries Guide at this link:
Well, I managed to get the starboard side plugs replaced. I have unseated the port side coil cover, but Dante remove it without removing the fuel line. Really? Is there any other way? Again, my car is a 2005 US spec XJ8 Vanden Plas. Thanks
Got the port side (bank 2) coil cover, and was able to remove #2 and #6 coils. There are obstructions for #4 and I have t begun to cry about #8. Also, I have having a darn time pull the coil connectors. Hints?
Also, I have having a darn time pull the coil connectors. Hints?
Yeah, those are a pain. I use a wide plastic trim-removal tool or a wide flat-bladed screwdriver to gently pry/push the connectors off of the coils while holding the connector lever down to release the tab catch. When you reassemble, put a little dielectric grease around the outside of the connector on the coil (not on the electrical terminals) so the female half of the connector will not stick to the coil the next time you need to disconnect them.
Well, I managed to get the starboard side plugs replaced. I have unseated the port side coil cover, but Dante remove it without removing the fuel line. Really? Is there any other way? Again, my car is a 2005 US spec XJ8 Vanden Plas. Thanks
I have a 2005 XJ8L that doesn't seem to have the same obstructions yours has. Will you take a pic and post it so we can see what you are referring to on the drivers side?
I have unseated the port side coil cover, but Dante [can't] remove it without removing the fuel line. Really? Is there any other way?
You don't have to disconnect the fuel line. Once you have the coil cover popped off of its mounting studs, I think the secret is to get the end nearest the firewall to move downward 2 or 3 inches so you can tilt the forward end up and then snake the cover out from between the cam cover and the oil dipstick tube and other obstructions.
OK. The coil cover is off and I have replaced all plugs except #8. There is an insulated box around the master brake cylinder that makes it seem impossible to remove the #8 coil. Disassembly of the box looks like a major effort (removal of the wiper arm abs cross brace at a minimum). If I can get that coil off, I am certain I can do the plug R&R. So close, but so far away.
OK. The coil cover is off and I have replaced all plugs except #8. There is an insulated box around the master brake cylinder that makes it seem impossible to remove the #8 coil. Disassembly of the box looks like a major effort (removal of the wiper arm abs cross brace at a minimum). If I can get that coil off, I am certain I can do the plug R&R. So close, but so far away.
To do that, you may need the magic extended tooling that DonB just showed above
Thanks paydase. That'll get the spark plug out, and I am fairly confident I can do it. but I first have to get the coil out of the way. This is the challenge - how to remove the #8 coil? I have it unplugged, but there is insufficient clearance between the valve cover top and the insulated box that surrounds the master brake cylinder to remover the coil. Any advice?
OK. The coil cover is off and I have replaced all plugs except #8. There is an insulated box around the master brake cylinder that makes it seem impossible to remove the #8 coil.
Getting the #8 electrical connector off without breaking it can be tough, but go slowly and use the same technique I described earlier and you'll get it.
To get the coil out, I use a plastic trim prying tool inserted under the lip of the coil to help encourage it to come up, while pulling up on the head of the coil with my other hand. A wide-bladed screwdriver could work too, but you don't want to damage the coil or cam cover. Once the coil pops off of the spark plug, you can lift it and twist it so that the head and angled mounting tab will just clear the insulated box around the master cylinder. It will rub somewhat, but it will come out. The rubber boot on the end of the coil will have to bend a little as you extract the coil, but that's OK - it's rubber.
Sorry I haven't responded sooner. I need to update my profile as "somehow" notifications of replies have been going to my wife's eMail instead of mine.
I gave up on #8. I was successful in removing the connector, but could not find enough clearance (no matter what) to remove the coil. I re-assembled everything, then put the car away for off-season storage (it's up on a lift). Sorry, no photos... and can't imagine I'll ever want to voluntarily disassemble the port side covers again.
Before storing it, I had the dealer change the fuel filter (again) and waste some of my money on a fuel injector cleaner treatment. If the stutter problem and MIL return, I'll replace her with a much less finnicky Ford Fusion Platinum... without the disappointments of a power driver head restraint that no longer works, a passenger side rear DVD screen that inexplicably stopped working, and a passenger mirror that no longer power folds (thanks to an overly aggressive & quick car wash attendant).... plus an out-of-date nav system (no voice controls), no Bluetooth connectivity, no passive entry, and no cooled seats. But I do love the handling, smooth ride, and acres of real wood.
A Jag is like a dog... really sweet, but occasionally slips up in the obedience department.
More like a big cat, than a dog. Give me the best of everything, and we'll get along fine, or i'll puke those substandard parts up on your carpet like a hairball. The #8 coil on my 04 XJ8 was a very snug fit to get out, but it came out easy enough with a little turning, & prestige applied. The plug was then a non issue.
12-10-2016 | 03:30 PM
Misfire on 2004 XJ8
Give me the best of everything, and we'll get along fine,
or i'll puke those substandard parts up on your carpet like a hairball.
The #8 coil on my 04 XJ8 was a very snug fit to get out, but it came out easy enough with a little turning, & prestige applied. The plug was then a non issue.