I just bought a beautiful 04 xjr. It had some problems that an o2 sensor took care of. Yesterday morning i got up and washed the car and sprayed the engine compartment. When i finished I started the car and it was running good except the restricted performance came up. I went approx 1 mile at 20mph and stopped the car for a min. When I tried to restart it runs very rough if at all. I can feather the throttle and keep it running but it is very rough also. I pulled all the coils and sprayed electrical cleaner in the plug wells and the connectors. I let it sit like that over night and reassembled this morning with no changes.
I need help bad. Originally I got a p0327 code but i went away and no codes are showing up now. Do i have a bad coil? Spark plug? How can i diagnose with no codes being generated?

 

What did you spray on the engine? If it was water under high-pressure you need to go over all the connections on the engine wiring loom and check for moisture in the loom and at the connections.

 

Water and electricity are generally incompatible.

Jaguar issued recommendations in 1999.

bob

 

It is somewhat amusing that such a TSB needed to even be issued at all.

 

This was just a water hose.

 

I pulled all the coils and sprayed electrical cleaner in the plug wells as well as the connections. I also sprayed whatever connections I could easily access. The car was running 100%perfect prior. could the coils have been damaged? plugs? If so a code would be generated, correct? If not can coils be tested?

 

Yes, there are COP (coil on plug) testers.

 

You may need to separate the loom connectors and dry them out. Just spraying them externally may not remove the water or condensation.

Leave the engine compartment open, if the weather permits, to help dry things out.

 

Even a hair dryer might help if you get things warm rather than hot.

 

I don't miss the days working at the Jag dealer trying to get engines running again after customers washed the engine, then arguing that Jaguar warranty will NOT cover 'self-inflicted' damage and labor costs involved.

I would suggest a small spray bottle of 'simple green' or similar All-Purpose Cleaner and a handful of rags. Labor intensive but safer in the long run.

bob

 

I am a "car guy". I've had a lot of cars in my time. I have cleaned a lot of engines without damaging any. I know how to wash an engine compartment. I was using a water hose set to shower. I did not drown the engine nor use high pressure or a jet.

 

"Car Guy" some time do made the misstate, that what your "know it all" and "clean a lots of engine", "know how to wash the engine compartment" lead to fail of your car, you have owned many car before, but your XJ was new to you, there is one more new for you to learn. This is old but it might help; how about the alternator and battery terminals, Jag. is very sensitive to electrical current. Sorry about beginning of my comment,don't be feel insult, but in this forum or any other forums, we here to learn what we don't know and help others what we know.

 

Putting a bit of cling film on components that might be susceptible to water is a good idea when washing down an engine compartment. For me, I think you've just been a bit unlucky. I am sure you didn't "Niagara Falls" the car, but sometimes water creeps into where you wouldn't think it would ever go !

 

I'm pretty sure that whatever happened isn't the result of water. After I sprayed it I did drive it approx 1 mile@20mph before it happened. I have let it run long enough to get up to temp several times. The heat alone should dissipate any water. Plus fans blowing on it in a heated garage for the days.

I'm gonna focus on the problem at hand. What can possibly cause an extremely rough idle? So rough it does when I shift it into gear? And not generate any fault codes?

 

Shorted coil unit(s) do not always turn on the MIL or show up as a misfire DTC.

 

Thank you. Good too know. Ill try systematically unplugging them to test.

 

Good to know that washing the engine did not cause this.

bob

 

You might've sucked water into your engine. The air intake scoop is right on top and it immediately drops down into the filter box. One decent splash in that area could do it. Then, as you started driving the force of the incoming air could've caused the water to creep right through or around the filter after a mile or two. Just a couple of drops of water will stop a spark plug from firing and that cylinder would stay cold and the water will just sit there. Pull a couple of spark plugs and see if they're wet.

 

Funny that you brought up this issue when you did. I had a similar problem over the weekend as I cleaned (washed, for simplicity's sake) the engine to get rid of coolant splashes and grime.
For the above reasons, I left the engine underguard off and went on to the carwash to carefully do it like I have with every other car I have owned.

Long story short, my car shuddered and started running rough and the "restricted performance" light came on. Luckily mine came with codes - P0323 and P0327 I believe, or whatever the knock sensor ones are.

My only thought was to drive the hell out of it to get it hot enough to expel & evaporate any moisture. This worked for the first night, but the issue came back the next day but so far so good.
Good thing the 6sp transmission allows me to commute in most conditions without going over 3,000 rpm.

I realize without codes, my story is going nowhere for you, but I'll say not all cars are made equal. This very engine has been washed in the past with no issues. However, I had a Benz that didn't like getting wet with the hood up. Driving it as fast as I could for as long as I could was the only way to get rid of the multitude of mysterious and unrelated codes.

 

Ok, last night I systematically checked all the coils. I started by unplugging #1 no change. Then #3 no change. Then 5 then 7 without any change to the already horrible idle. At this point the entire bank 1 is unplugged. I go to #2 and I notice a difference. Same with 4, 6 and 8. Do I reconnect bank one and disconnected all of bank two and notice the same difference w/1,3,5 and 7. Troubleshooting the original problem I had when I purchased the car I put in a new bremi maf sensor in and it didn't help my problem. Yesterday I reinstalled the original Denso sensor. And all is back to normal and running 100%again. I slept well last night. Thanks again everybody for the help. Lots of valuable knowledge in this forum.