I'm getting these codes: P0193 - fuel rail issue.

About 3 months ago I reset codes P0088 - why? Sometimes these sensors seem too sensitive.

Here's the thing - when I start the car its at 1100rpm for about 2 mins gradually idling down to about 700rpm. Mileage is 15-17mpg locally and 23-26 on the highway - which is unchanged since I've have the car or seen these codes.

I'm wondering if a fuel injector cleaner/additive might help before taking it in for what could be an expensive repair. I have done a lot of repairs myself but with an injured back I can barely get in and out of the car and its pretty cold out so....I may have to give up and get a mechanic.

So - anyone have any experience with using a cleaner? (I have never put any additive but high test petro in this engine - 128,000 miles.)

Thank you!

 

You may want to check the XK / XKR forum as well. The 4.2L in there is almost identical with yours.
From what I read you should check for any leaks in your air intake and vacuum line piping and check electrical ground and continuity on the fuel pressure sensor connector. So far so cheap, if that does not help, you may need to replace the fuel pressor sensor.

Chris

 

Ideally you should try and get a full Jaguar code from the car, it will be more descriptive of the error. This high level code is trying to tell you that there's a problem with the fuel supply. This can be the sensor itself, its either failed or shorting to ground/power; or the fuel pump, you can't easily tell from that code alone.

But what will be happening is that you will not have the correct fuel+air mix. On a cold start the engine will be in open loop mode and relying on the MAF, MAP, fuel rail, temperature sensors to get the right fuel+air mix. The idle will be higher than normal and probably a bit rough. If you try to drive immediately, and put your foot down hard, the engine can misfire because of the incorrect fuel+air mix. Once the O2 sensors have warmed up (usually 1-2mins) then the car will go into closed loop and it will be able to adjust the call on fuel based on the O2 readings, the othersensors are less influential at this point. If you left the car idle from start you'll notice the rev's drop when it goes to closed loop. The ECU is compensating for the issues by using the O2 data. However this is imperfect because the O2 data is post burn so there is a lag between the burn and O2 sensor reporting back to the ECU, so the ECU is altering the fuel-air mix based on what just happened in the engine and not what the ECU is asking the engine to do. Whilst driving at consistent low rpm then the time delay, and rate of change, between fuel+air in and burn out is lower and the ECU can manage this within its tolerances, but you will have reduced engine performance and efficiency because the mix will be ever so slightly off. If you put your foot down and take it to high revs then there is a lot more air being drawn into the engine very quickly, the tiny delay in the O2 sensors telling the ECU what just happened will be material and the ECU will make incorrect calculations and put in the incorrect amount of fuel, so you should find that the engine hesitates and/or misfires under heavy load/high RPM. If these fall outside of the ECU tolerances it will throw the car into restricted performance mode.

This is worse on cold days, e.g. close to freezing, as the air density increases compared to milder days and that changes the amount of fuel needed to be injected, if the ECU isn't getting good data from the sensors then its calculations get even more off when there's dense air being thrown in.

Also, at 120K you should have changed the fuel filter.

I don't think cleaner is going to fix this problem.

 

Thanks, great info!

My confusion related to past performance where I saw these fuel mix related codes, cleared them, and the codes didn't reappear for a year - 15,000 miles of excellent performance.

As it idles high, I would not drive it - you are confirming that is a wise decision. It doesn't hesitate or misfire/backfire - otherwise running well with good mileage.

Unfortunately, very hard for me to examine more deeply in the cold.

Thanks for the help and educated opinion, much appreciated.

 

Great ideas, thank you Chris!

 

i had the same problem and it was fixed by taking out the injectors cleaning and flow testing them and now it runs perfectly with no engine management light any more . I had a fuel injection guy do it and it wasnt expensive .

 

Thanks for the input. I will probably take it in. Good to hear your's was a small issue.

Maybe I'll be lucky!


PS I did use the BG 44k, have driven 80 miles and it seems to run another.