i bought this car with the head gaskets blown...i took it to friends shop and he convinced me to do a complete rebuild...so 6 months later i picked the car up and its misfiring..runs smooth under throttle but really rough at idle..plugs in back 2 on drivers side look really white and the plugs on other side look normal,slightly gray and brown..scanner says misfiring on #8..strong smell of gas,i assume coming from the misfire...any help would be greatly appreciated..im out of money and want to figure this out asap..im just hoping its nothing major...thanks scott

 

Plugs and coils on the last two would probably fix it...or you can do one cylinder at a time until you find it.

 

i put new plugs on drivers side bank and its running good..idles fine,gas smell is gone..i only drove it about 5 miles so who knows..the restricted performance went off but check engine still on..will have to clear with scanner i guess..does the jag have a built in scanner like my c5 vette does?

 

Just drive it for several 'drive cycles', the CEL should clear on its own.

Any other symptoms on that bad bank to indicate why the plugs went south? Any fluid in the plug wells? Were the plugs platinums? Did you make sure to put iridiums back in?

 

ngk bkr5e-11..thats what was in it..i have no idea why all plugs on that side are white...o2 sensor

 

theres still a smell of gas in the cabin..im losing my mind here...

 

give it some time on the gas fumes, it may take some time to clear from the cats

 

still have strong smell of gas coming into cabin..its gets worse when i put gas in car..seems to be coming from trunk area..i did put new filter and fuel pump in right before i sent it to the shop..any ideas?car is running and idling much better now that i changed the plugs,but still have this strong smell of gas..makes me not wanna drive it..

 

The gas smell sounds like something to do with a canister and hose near the right rear wheel. Read this: https://www.jaguarforums.com/forum/s...ighlight=smell

 

It could still be burning from the CATS too, if you want to run an EVAP test on the fuel system, feel free. It is not uncommon to have a leaking vent tube and inoperable partially canister close valve, but when that usually happens, there is a code thrown with a MIL indicator on the dash...at least for me it did.

 

now the scanner says its misfiring on number 2..and something about fuel/air metering..its hit and miss with it idling,sometimes pretty smooth then other times kinda shaky...

 

changed plugs on other side cause 2 was misfiring..plugs are white like the other side was.....

 

ive been searching about vacuum leaks..he told me the line going to the brake servo had broke and he fixed it..he gave me a diagram shwing it to me..could this be causing the misfire and the gas smell?

 

Swap coils over too, see if the misfire jumps back to the other bank.

Vacuum leaks can cause alot of havoc, if bad enough, it can cause misfires. Misfires cause unburnt fuel to enter the exhaust (and again, the CATS). <- last time I'll say that. Too much into the CATs will permanently damage them.

Fix the misfire, see if the smell goes away. In other EVAP leak threads, the purge valve (aka CCV) gets stuck open from a vent tube rusting and pieces falling into it.

One problem at a time. keep chasing the misfire and leak.

 

took it back to guy who rebuilt motor..picked it up and it ran fine for about 10-15 miles and now back to same thing..heres the codes i pulled..p1396-manufacturer control ignition system or misfire...p0171-system too lean bank 1...p1000 manf control fuel air metering auxiliary emission controls...he did something with a vac line that went to brake servo..??please help..somebody has to know whats going on...gas smell was gone almost compeltely until it started acting up again...

 

No idea if this is related...Link

 

I know this is an old thread but hopefully my experience might help somebody still experiencing misfire problems. I'll try and keep it brief...

I bought a '99 XK8 Coupe with 114k miles and a reasonable service history at a classic auction. Prime reason for selecting it above the other four on sale were the rear quarters and inner arches were very good. A six year MoT history report showing no welding and very few advisories confirmed this. I expected some issues and they manifested themselves immediately on my first drive (there was not an opportunity to try at the auction). It misfired badly on part throttle. Idle was perfect and full throttle was equally impressive but part throttle was awful and also confused the gearbox. Once it warmed up it was marginally better but still horrible. I first did the simple stuff whilst waiting for the code reader to arrive. It was checked for air leaks (un-scientifically by spraying hoses on a running engine with easy start). Plugs were bad (you could have parked a van in the gap) and of unknown age so I swapped in copper Bosch plugs. No improvement. Throttle body and MAF sensor were also cleaned, to no avail. The code reader arrived and advised the left O2 was bad. I bought a pair and had them fitted. Logic said that it being worse from cold might indicate O2 sensor heaters as a probable cause. Anyway, there was no improvement after they were swapped out. My mechanic, who owns a supercharged XJ8, said he bought his Jag cheap because of a similar part-load misfire. It had been to three garages, including a Jaguar franchised dealer, and none of them diagnosed the problem, It was only a parts-swapping exercise with another XJ that diagnosed his problem as a faulty MAF sensor. I noted the observation and the MAF part numbers and logged on to the online auction site we all love to hate to procure a replacement MAF. It's a semi-generic part as it fits a Subaru Forester and a Mazda CX as well as a Jaguar. Fitting took two minutes but what a transformation! Fault cured, gearbox regained it's composure and corners on rural lanes came up much quicker! OK, I might have thrown a lot of parts at it that it might not have needed but total spend was well under £200 - copper plugs £14, code reader £28, two O2 sensors £31, carb cleaner £3.50, MAF £28.50 plus a bit of labour from my tame mechanic.

I hope my experiences helps on a few levels: 1- the codes are not gospel, 2- copper plugs work, 3 - generic parts work and 4 - a bit of mechanical experience can be priceless.

 

If its showing system too lean then either its an air leak on the induction side or one or more cylinders are not firing. Now the petrol smell may or may not be related, the injector(s) may be leaking on the inlet manifold or the pressure regulator and quick release connectors. The system trying to over come a lean mix by injecting more petrol may be the source of the smell? I would check the injector connector plugs to make sure they are seated and the coil connectors then read the codes again. The coil connector clips are known to get brittle and snap off, 2 of mine are held on with tie wraps for that very reason. Check the fuel trims before and after everything you try so that you know if the situation has improved or not. You have to remember that the system cant compensate for an issue on only one cylinder , so a misfire on any one cylinder will cause the system to see excess oxygen in the exhaust via the o2 sensor , just because that oxygen hasn't been used via the missing cylinder. So it will increase the fuel trim for that bank to try to correct it. Anything over +25% will throw a lean code. As your codes tend to show just one bank in a lean condition, that points to an issue on one side as a more likely cause. So concentrate on that one bank unless of course, the o2 sensor plug have not been swapped over by mistake as I don't think that they are handed? you could check by creating a lean condition on bank 2 by removing an injector connector on that bank and see if bank 2 fuel trims go up? Very difficult without having the offending item in front of me.

 

With white plugs that is almost always a sign of an intake manifold leak.