So i bought a used 2009 Jaguar XF a few weeks back with 125k on it. Everything seemed fine till I got home and 2 days later the check engine light came on. The two codes that started coming up were a misfire on cylinder 7, and the misfire code within the first 1000 revolutions for that cylinder. So the mechanic looked at it for a couple different days and could not figure out what it was. They did a smoke test, they checked the spark plug, the coil, and the injector. They could not figure it out. They also looked down in the cylinder with the scope to see if it was wet and didn't notice any leaking. They did a coolant pressure test because the coolant level low light was coming on and everything was good, and that warning quit coming on. The car randomly at times, not all the time, misfires after startup, but it only happens every couple days. And its just very brief right after startup, and is very quick. It never does it while im driving and I have not noticed any misfires while actually driving, either in town or on the highway.

Does anyone have any ideas ?

Also: sadly the sunroof drain was clogged last weekend during a heavy rain, so part of the sunroof area flooded over the passenger floor mat/visor, down into under the glovebox area. The only thing that has completely quit working is the heated/cooled seats, and the mechanic thinks the module got wet and its done for, but he wasnt sure because he couldnt get a good wiring diagram to check over everything, and so he wanted to let it dry out more to see if anything changed.

Does anyone have a wiring diagram on that for the heated/vented seats to see if i could get to that? I dont know if i could just buy a used module and replace it myself. Is there only one module for both the driver and passenger seats?

Thank you!

 

If it were me I would swap the #7 plug and coilpack with one of the others and clear the code and see if it comes back #7 or the other cylinder that you swapped it with. If it does not go to the other cylinder I would add BG44K to the fuel and see if it cleans the injector and the code goes away.

As for the wiring diagram use the link below.

Link JagRepair.com - Jaguar Repair Information Resource

 

Thank you for the info. I probably forgot to say it correctly, but we did swap everything with cylinder 7 and even after doing that the misfire kept coming up for cylinder 7. Thank you for the wiring diagram too, as I can tell it's probably a little bit to confusing for me I will look into BG44K.

 

The BG44K is what Jaguar uses and in my opinion it is the best on the market.

Gus
JagRepair.com - Jaguar Repair Information Resource

 

Thank you. I will order some.

 

I went and was actually able to get some today. I will let you know how it goes after a little bit of driving on this full tank of gas with it. Thank you.

 

Most of the time you will see a difference shortly after installing it but the big question is will it fix the problem. Please provide an update.

Gus
JagRepair.com - Jaguar Repair Information Resource

 

Haven't drove to much yet but I did notice on the way home tonight when i accelerated pretty strong that there was some whitish looking smoke that came out for just a brief second..dont know if it was from that or if that's a good or bad thing..no check engine lights have came on again so far. I will keep this updated.

 

I think there is an overall difference with gas mileage so far..but the check engine light for the misfire came back on. But thank you for helping me figure out a good cleaner to use from now on.

 

 

Sadly as you can see above, the tester of the coolant system changed to yellow. It took a long time to do it, but eventually it finally changed to that color. It looks like a head gasket issue I'm assuming. Like I said. The car drives perfect. It has no issues while I'm driving it. The only time it has an issue is cylinder 7 will randomly misfire after startup so idle will be rough for like 10 seconds, and that's it. But I'm assuming that is why no one could figure out what was wrong with that cylinder, because there must be a small leak somewhere in the head gasket going out into the coolant system. I have not lost any coolant at all or anything like that, but this is not good news..so I dont even know where to start.

 

First I would take a compression test and see what comes up. Do you have any indication of coolant in the oil? It could be a sticking injector. I would check all avenues first before digging into a head gasket.

Gus
JagRepair.com - Jaguar Repair Information Resource

 

The mechanic I thought told me he did a compression test and didnt find anything wrong. I dont see any coolant in the oil either from what I'm seeing.

 

He also told me he checked the injector and it wasn't that either..

 

The injector could be working but clogged. If the fuel presentation is not right in that cylinder it could cause your problem. I would pull all the injectors and have them cleaned. I have a company link I used on my page that will first test then clean and retest and provide you with all the test readings.

This is the link. http://www.injectorrx.com/

Gus
www.jagrepair.com

 

The dude has exhaust vapors in his coolant system, plain and simple. That fluid doesn't turn from blue to yellow for no reason. The test is conclusive, so quit trying to repair injectors.

It's game over.

 

I wish i could say this wasn't the case but it is. I'm hoping to be able to get some help on getting the issue resolved from the dealership that sold it to me, but probably not, we will see. Anyways, it sucks, but it is what it is I guess.

 

You sir are a pleasant person to deal with. My direction was based on the comment that the compression tested good.

Gus
JagRepair.com - Jaguar Repair Information Resource

 

Thank you for trying to help though. This has been the most confusing thing and frustrating thing I've gone through ever with a car, especially just buying it a month ago.