OK, this is baffling me and 4 "master" Coventry mechanics I'm spending $$$$$ on. 2000 XKR on hard acceleration sputters, feels like either missing on several cylinders or starving for gas. Smooth acceleration no problem up to 110 mph (then I slowed down as the red and blue lights behind me were annoying). From standing start, tromping on it, no issue for 100 yards or so. Driving at any speed and hitting it, again, sputters like crazy. No recorded faults for the OBD to interrogate. New plugs, coils, fuel filter, both primary and secondary fuel pumps. This is really baffling. My thought is "what tells the secondary pump to kick in?" Is there some signal generated that tells these pumps to provide fuel on a hard demand (like kicking in the passing gear demand). Why under normal acceleration........smooth acceleration........it runs fine?

Any thoughts or prayers?

Thanks, Mike

 

Certainly sounds like the second fuel pump has failed.

 

Welcome to the forums Mike,

Ignition faults would almost certainly set codes so my vote also goes for fuel pump.

Graham

 

Thanks for the reply, indeed perhaps a faulty secondary pump was installed. Now, I also wonder how does the secondary pump be told to turn on?.........ECM signal? could it be that the ECM isn't sending a "turn-on" single to the pump to activate? Or, (which I can't find out) is the secondary pump always on and is on the same relay as the primary?

Got to get to the bottom of this...........................

 

As i recall you can pull the fuse for the primary pump. It will failsafe to run on 2nd pump. If she dies = bad 2nd pump.

XKR experts will correct me if I recall wrong.

John

 

Finally, mystery solved. Sputtering Jag. So, plugs changed, fuel pumps changed, check valve, filter as well. THE PROBLEM WAS THE AFTER MARKET COILS. Yes, supposed to be spec OEM. Car ran fine for months then the sputtering began. Seems these coils (4 of them on the right side, you know the side that you have to disassemble the engine to get to) would break down under load. Acceleration demand. New Jaguar coils..........no problem, runs strong. However during the trouble shooting mode to determine if perhaps the ECM was bad he wired past the relay for fuel pump #2 and had it constant on not waiting for the ECM to signal the relay to turn it on. Well, does that make any performance difference? BAM, this car screams. Don't know why exactly as there isn't additional fuel pressure, that's regulated. Not more fuel to the rail but we tested it three times. Standard with the ECM trigger for pump #2 and constant on. Yep, if you want more performance from the "R" it does do it. Now the supercharged V8 which Jag needed a better fuel pump configuration put two identical pumps instead of just creating a "better" single pump. This does make a difference in the low end, mid-range and high end.

 

Various types of aftermarket coils have created many issues on these cars over many years. If you decide to go with aftermarket coils, always post what you are considering here on the forum prior to purchasing them. There is safety in numbers and you want to ensure that others have had good experiences with said coils before you commit to them....

 

+1 on not buying cheap *** China coils (as I did&#128563
I got 8 useless coil packs and even paid import tax for it😱.


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