Hi. My 1999 XKR (UK) has knock sensors reading 570 k ohm and 590 k ohm.
No fault codes showing. If i drive very sedately and keep revs low all is ok, if I go WOT the car cuts and bucks very badly.
If i drive part throttle and keep on going it will rev up the range to near limit, but wont push..
Sparks and coils replaced, o2 sensors replaced, fuel filter and pumps checked and pressure from the port checked. All seem ok and now trying to really narrow this down.
Starts first time always but can run a little rough till warm. i have tried 3 second hand mafs, nothing really seems to change the issue. So looking at knock sensors.
If I temporarily replace the sensors with a 560 k ohm resister to trouble shoot, any thoughts? Not wanting to take the charger off till I'm sure, it gets very cold in the UK round this time.

Any help greatly appreciated

 

I'm sure that a problem with the knock sensors would trigger a DTC P code as this is a critical emissions issue. I would also have expected an immediate "restricted performance" warning and probably a no-start.

Is your OBD reader a good one/ Can you try another brand?

The resistances do seem high but as they are both the same I suspect the reading is correct. Are the sensors completely out of circuit with everything else when you measure them? I read the sensor resistance was supposed to be 200k so this would be the resistor to try if you want to experiment but I'm not 100% sure as I've never measured mine.

Richard

 

It may be that one of your fuel pumps has failed.

 

Hi. Both pumps are working fine, i can jump the second one and its functioning. I replaced them due to this issue about a year ago. Ive been hunting this problem down for quite some time.
In this post:
https://www.jaguarforums.com/forum/x...-249936/page2/

admittedly on an xj, but similarities.. the older knock sensor, one I think I have but cannot see it, has a resistance of 550kohm and the new type 200 kohm.
Ive seen others have knock sensor issues with no faults. By using the resister i can at least rule it out.

 

Having only one working fuel pump wouldn't produce these symptoms anyway - you obviously have at least one of them working or you wouldn't have a running engine. Did you actually replace the fuel filter and I take it you have new fuel?

Any scanner will give you the live data for the ignition advance - I would be looking at that before anything else. While you are at it you may as well look at things like your fuel trims, MAF value etc to see if anything obvious is going wrong.

 

That's interesting. I'd not seen reference to the 550k version before. However, the bad news is that if 550k is the nominal resistance and yours are 570k and 590k then even the higher one is only 7% above spec which will be within range.

Richard