Just filled up with mid-grade fuel instead of premium. Car has been running perfect. Today I got check engine light and diagnostic showed misfiring on 7 of 8 cylinders, and two ox sensors not functioning properly, was told they're either just dirty or need replacement. Any clues, comments, etc.? Would just switching the mid-grade make a difference? Also getting "restricted performance" message.


Thanks in advance.....really curious why it would just start immediately after I switched gas.

 

If not then it's a very remarkable coincidence.

Graham

 

I'd say that a tank of 'bad-gas' (water contaminated) is more likely.

bob

 

Thanks....was thinking it might be the gas, but that would be too easy....any suggestions short of draining the gas and refilling with premium??

 

Graham


that's what I thought as well. Only drove from the gas station home after filling, and this is first time I've had it out since.....

 

Octane level of the fuel would not cause this. Contamination (water) would.

 

+1 contamination. I know one member who uses regular without a problem. The knock sensors will cause the ECU to retard the timing if necessary.

 

can't imagine how contamination got in there.....had a full tank when I bought the car; this is first refill.....???

 

"and this is first time I've had it out since....."
"had a full tank when I bought the car; this is first refill....."

Water contamination from condensation over time in mostly empty tank, and then stirred up by refill?

Or does this only happen with boats?

 

I would let the car sit for a while (a day??) and remove the fuel line to the injector rail.
Aim the disconnected fuel line into a glass jar and energize the pump for a few seconds.
Look at the fuel and see if there is contamination???(commonly known as the 'clear & bright' test.)

bob

 

Don't be surprised if you find that you dispensed sludge into your fuel system. I once had an experience that completely ruined the fuel system on a volvo. It was a long time ago but I remember how disappointed I was to discover that a fill up at a name brand station cost over a grand to fix. Just drop the fuel filter and dump out whats in there and you may find stuff you don't want to find. Good luck

 

Stick a can of BG 44K in the tank, top up and run it until the tank is near empty.

 

Bob


sounds like the best solution yet...will give it a try. Thanks

 

Will give that a try...thanks

 

I'll disagree. BG44 won't fix contaminated fuel.

Is there any chance that water got sprayed on the engine?

 

Mikey


No chance regarding water on the engine........what does BG44K supposed to do??


Thanks

 

The BK product might help carbon contaminated injectors. This issue is not something that happens out of the blue and is almost unheard of on Jags.

 

BG44K is a fuel system and injector cleaner, and highly regarded by many. There is also "dry gas" to absorb the moisture, which might be a good idea. I can't remember the brand name, someone might chime in.

 

I'd follow Bob's suggestion. He knows the cars...

 

To all who responded to my issue, I thank you for your valuable input; it speaks volumes to the value of the Jaguar forum. Having said that, here's the current status. As I mentioned in my initial post, the car was running very rough and check engine light was on. Diagnostic showed missing on 7 of 8 cylinders, and person running the diagnostics suggested that there may be a problem with the ox sensors, which could be dirty or defective. (Did not realize at the time that there was not an actual code on the diagnostic test that indicated ox sensor function issue, just an opinion from the tester). As it turned out, I have worked on the engine the day before, removing the engine cover to do some minor repairs and touch-up. Of course, to remove the cover, the oil filler cap must also be removed. After the "misfire" issue, I put the oil filler cap back on, and the car then ran fine, no apparent misfires (?). The next day I had another diagnostic test performed, still showed misfires, but the very last line of the printout said "Systems Pass".....the guy running the test says the "misfire" notes sometimes stay in the system until it's cleared. Car was still running smooth so I took it to the local service garage, explained the situation, trying to decide if I should have them go through the engine to see just what the problem was (if there really was a problem) but we decided to clear the check engine light first to see if it would go out or if it would go on again the next time I drove the car. The light went out and has not come back on, and the car continues to purr like a kitten (or Jaguar, if you will). Sounds strange, but that's where we're at. Apparently running with the oil filler cap off had an effect for whatever reason. So now we'll go merrily along and hope the condition is fully resolved. Thanks again for all the feedback and suggestions.