Engine Fault - Poor Performance error message

Hello Forum,

New owner of a '97 XK8, Convertible which has checked the box for ‘Stage 1 - Mid Life crisis purchases’.

I am in the Seattle region (across the pond, in the Peninsula area).

I purchased the car after a few days of agonizing over this car and a 2000 vette.
But as I am a Ford guy at heart, I went with the Jag.

Drove it home, no issues at all.
Next day, I did an interior detail (9 out of 10) and washed the car.
The exterior had some significant scratches (previous owner thinks it went through a fence?)
But some rubbing compound found those to only be in the clear coat. I will complete a small section of body work on the right rear quarter panel, then paint the entire car.

After washing the car, I started it up to drive it from in front of the front breezeway, and it had a rough idle. No fault codes. I only drove it about 50 - 60 feet, then parked it.
Went out this morning, and it started right up (still had a rough idle), and when I was driving into the office, the ‘ENGINE FAULT’ light came on, it started mis-firing, and then I got the ‘POOR ENGINE PERFORMANCE’ message, and the car went into limp mode.
I did spray down the engine lightly with a hose, but with very light pressure. I don’t think it got any more wet, than it would have if I’d driven it in the rain.
I have an air compressor at work, and was thinking I’d ‘blow’ any water sitting near electronics off, in case that was the cause?

*Note - Best location to pick up a scanner for this car?

Hi Michael, welcome to the forums, hope this isn’t too late, yes try blowing any moisture in the plug areas dry, I think you might be able to clear the code by performing a ‘hard reset’ disconnect the battery terminals and hold them together for about 30 seconds, please note if your radio needs a code then this will need to be input, hopefully there is documentation with the car that’s contains this 4 digit number.

Thank you for the response.
Unfortunately, there wasn’t much documentation that came with the car. Not even an owner’s manual.
(I found one on e-bay, and it will be here within a week or so).
The display area of the radio, has some black pixelation, so it’s not easy to read. Same with the temp control display.
My plan was to replace both in the near future.

For the battery reset. Do both terminals have to come off the battery? Or, can I just unhook the NEG and hold it against the POS? (Saw that in a YouTube video).

Thanks again, for the reply.
Hopefully I’ll be able to research my own stuff in the future, and not be a pest in the forums.

Try opening the Schrader valve on the fuel rail to check fuel pressure ( Be careful and stand aside, don’t want to spray yourself). Low pressure could indicate a clogged fuel filter or faulty pump.

Just unhooking the neg and holding against the Pos will work as well.
There’s a very good search function within J-L its the spy glass top right.

There was a lot more water sitting around the coil packs than I thought there was.
I found the covers, in the trunk, and will put them back on once I extract a broken screw from the right side. Without those covers on, the water was just pooling in those recesses.
Blowing the water out (maybe 1/2 cup, each side?) then letting her sit in the sun with the bonnet open for a few hours, made a world of difference. Idle has calmed down significantly.
I’ll give her some more time in the sun today, and try again.
I’m going to get her on the lift, and do a more thorough inspection.

Welcome to the club! I have a 2001 that I bought from the owner, and it had warning lights on, but ran fine until it went into ‘reduced performance mode’. Even then, you had drivability up to 3000 RPM, so I drove it and took it to my mechanic. It was two or three coil packs that were weak, and the ABS modules are famous for going bad due to bad solder joints inside (that can be fixed). Coil packs, it turns out, can be bought as a set of 8 for very little money on Ebay and Amazon. Fix the faults and enjoy the car. I like mine a lot and try to drive it often. Oh, get a turn-off switch for the battery, as these cars drain the battery as they sit. All the best.

Thanks for the info.
I drove it a mile today. Started out fine, but then went back into limp mode. Had to do a quick u-turn, and bring it back to the shop. I ordered some new plugs/packs already. Once they get here, I’ll swap everything out, do a hard-reset on the battery, and then try again.

The car has a battery-tender already attached to the battery. I just need to plug in the pig-tail into an extension cord. I’m assuming that the previous owner learned the hard way about battery drain. It appears this car has been sitting quite a while, based off the mold on the interior and soft top.

Hello again.
Swapped out the plugs and coil packs. Engine Fault and Poor Engine Performance messages went away.
However, right after I got the new coils/plugs installed, I disconnected the Neg battery cable, and held it against the Positive terminal for a little over 10 seconds.
Started the car, and got no mis-fire or codes…
But, now, I’m getting ‘Driver Door Open’ and ‘Passenger Door Open’ messages, even though the doors are shut. (I shut/open them several times, to be sure.)
Did disconnecting the battery (the doors may have been open at the time), cause this new error?

I can’t see any correlation between the two, when ever I have done a hard reset on my ‘99 XJR that hasn’t happened. I would think the two are coincidental, however try doing another one with the doors shut?

There was something on here about re-setting the power windows if the battery was disconnected, and there is a process for this,and it applies to the roadsters. It may have a connection to the door open switches.

Id try the reset again and see what happens. There are door closed micro switches that can go bad, but i cant see both of them going out at the same time.

Update “Door Open” error message is gone.

‘New-to-Me’ driver’s side window switch arrived this morning.
Installed it and had no power. Was thinking I got a bad one from ebay, then realized there was no power. ( I’d forgotten to reconnect the battery. :slight_smile:
With the battery back in the electrical system, the ‘door open’ error messages for driver and passenger side is gone. And, the dome lights above the rear-view mirror no longer stay on. The door microswitches must pass through that switch?

Also, heater control section was replaced by another ebay treasure. the LCD display works perfectly now. The radio arrives on Friday, and I was told it was tested and had a good LCD display. A little worried about a ‘code’ I heard about, that I don’t have, but we’ll see what happens after it arrives fingers crossed.

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There are you tube vids that show how to get the radio going if it doesn’t come with the code.