I was under the hood of my XJR one Summer evening, and forgot to close the hood afterwords. That night, we got a freak rain. Got the same symptoms as you. I tried all the things listed here, only to have rough idle and lights still on.

Ended up being water that got under the coil pack covers and was shorting out a coil pack. Dried it out, and it instantly ran perfectly.

Just another thought, in case the other things don't do it. PS: I had also read my codes. Cyl 8 misfire. Reading the codes is definitely the FIRST step at diagnosing problems on this car. It's nothing like my 66 Mustang where you can just look at it and know what's wrong.

 

supersport beat me to it! If drying the TB connections, the knock sensors, and anything else on the top of the engine that could have gotten wet electronics, then I was going to recommend pulling the coils and drying out the plug wells (with the plugs still in). Paper towel, then maybe compressed air...let dry for a couple hours while you focus on the towel drying each coil. post back with good news!

 

Thanks to SuperSport, meaculpa, Sparkenzap, Glendoramike, h20boy, Gus, or anyone else i missed. I am going to try to dry these coils, TB connectors, other advice, etc. tonight when I get home from work. I will let everyone know how it came out. Thanks, Louis

 

You have no idea how many times this Forum has saved my behind when I was completely lost. Much of the time I'm sharing information that I got from here and just repeating it back after I've used it myself. Sometimes, it's my own experiences or knowledge, but again, this Forum is a life saver, and all the helpful people on here, many of whom do this in the real world for real money.

 

I purchased an Actron OBD II Pocketscan today and got the following codes: PO122, PO222, and P1111. Could anyone please point me in the right direction? Thanks, Louis

 

The P1111 means that certain emission componets have passed their tests. If you clear the codes, it will change to P1000 meaning that they need to pass their tests several times to switch back to P1111. You can't change this on your own.

The other two have to do with the Throttle position sensor. It is on the side of the throttle body and has four wires going to it. The plug loves to take in water and screw up your driving time. Push the lock inward and then disconnect the plug. Spray WD-40 onto the prongs that you see and around them and into the plug to clear out any water. Connect it and disconnect it several times to clean the connections. Then start it up and see if the check engine light goes out and the codes go away. It may take a warm up to get it done.

It is possible that the pedal positions sensor is at fault. However with coolant around the Throttle body, I would go with the cleaning there first.

 

I have had the flu, so I am behind in getting the codes erased and restore running. The mechanic i have is supposed to come tomorrow night and help me. i thought this would be an excellent time to clean the MAF sensor as well. I did clean the throttle position sensor, but it didn't fix it. I am going to try the accelerator position sensor to see if that does it. It would've been hard for coolant to have made its way that far, but maybe it just happened to fail at the same time the coolant hose let go. it has been a week and a half since I have driven it, so I am anxious. Codes P0122, P0222 are shown as pending, and P1642 came on once. Somebody had said it may require a warmup for the smooth running to return. I was hesitant to do this due to failsafe mode, and the poor running. Thanks again for all your help, Louis

 

The P1642 refers to a CAN problem. It seems to be having a problem with communication between system components. You may have a short circuit somewhere and you need to use the other codes to track it down. As long as you have coolant, oil and oil pressure, you can warm it up. That is how I found that I had fixed my P0121. It self cleared. Just don't drive it yet. Baby steps first. The p1642 may clear up too. Look for damaged wiring too.

 

P1642 is almost certainly a vestigial fault from connecting the scanner. It is regularly reported here. In fact, on a car with no other faults, it has appeared after the scanner was connected, the CEL illuminated and then this fault was the only one there.
P122 and 222 refer to a bad feedback from the redundant tps sensors. It might be a result of wet connectors or the known throttle body plug problem. I would clean the throttle body connector really well, rest and see what happens.

 

My jag is back to running smooth again! It was indeed the throttle/accelerator sensors. I cleaned the remaining one last night, and let it warm up. I got everything back. The lights went out, and I was able to erase the codes. Thanks again, Louis