2007 XKR Misfire on revs, no power above 4k rpm- clicking sound
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From: Uk
@H9haaris
https://www.jaguarforums.com/forum/x...porary-155887/
I had multiple misfires and restricted performance. No Cat codes. Replaced cats, no more issues. There is a link somewhere here that leads to decent cats on ebay and a decent price.
https://www.jaguarforums.com/forum/x...porary-155887/
I had multiple misfires and restricted performance. No Cat codes. Replaced cats, no more issues. There is a link somewhere here that leads to decent cats on ebay and a decent price.
Hi, ive got my replacement cat ready however i still dont have full performance with the gutted cat on the left bank, it seems to be overfuelling heavily and igniting fuel on the left exhaust, this indicates overfuelling destroyed the cat si now i need to ascertain whats causing it
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From: Kaysville, Utah, US
@H9haaris I'm afraid that's over my head. The gutted cat may be causing the O2 sensor to signal the ECM to overfuel? Some smart guys on here know the answer.
If you have that much fuel, one of your injectors is dumping way too much. That's the only way. Been awhile since I read this thread, can't remember if you checked/changed them.
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Joined: Dec 2019
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From: Durham, NC
I’m experiencing a persistent issue with my Jaguar XKR where the engine runs rough and misfires under load when revving from idle. At idle, the engine runs fine with no misfires, the idle does fluctuate so slightly, but as soon as I rev, I read multiple misfires across cylinders, rough running, and what feels like a cut off where I dump the throttle and it builds revs slowly once it hits a barrier then jumps through it but at that point it revs with an extremely rough sound
I’ve attached my SDD data logs for reference. Key observations from my logs include:
I have attached links to a YouTube video of the data logging, I have to go outside and rev the vehicle so there are idle spots in the middle but you can see when I rev where the chart goes I then come back lower the screen to more data and repeat, as well as a short of me driving on the road
I did just replace both MAF’s and this seems to have done nothing if not maybe worsen the revs on idle
any suggestions or knowledge would be greatly appreciated
https://youtu.be/r5GRUfizFcI
https://youtube.com/shorts/XcPT185BH...MjYI4rqgWVefLf
TLDR: misfire and rough idle, charts attached in YouTube video, jaguar gods and experts please help me figure this out
I’ve attached my SDD data logs for reference. Key observations from my logs include:
- Multiple cylinder misfires under load: Cylinders 2, 3, 4, 5, 7, and 8 affected, with the highest count on cylinder 8.
- Fuel Rail Pressure: Fluctuates between 360–390 kPa at idle with sharp, small spikes and drops. Under rev, rises to ~400 kPa then returns to idle level.
- Fuel Pressure Sensor Voltage: Matches fluctuations, ranging from 3.4V to 3.8V, showing a jagged pattern in the graph.
- Short-Term Fuel Trim: Swings sharply between -10% and +16% under load, indicating unstable fuel correction.
- Long-Term Fuel Trim: Increases from 5–6% at idle to 10–20%under load.
- MAF Sensor: Voltage rises normally with revs, but I haven’t confirmed smoothness under load yet.
- Throttle Position: Responds normally with pedal input.
I have attached links to a YouTube video of the data logging, I have to go outside and rev the vehicle so there are idle spots in the middle but you can see when I rev where the chart goes I then come back lower the screen to more data and repeat, as well as a short of me driving on the road
I did just replace both MAF’s and this seems to have done nothing if not maybe worsen the revs on idle
any suggestions or knowledge would be greatly appreciated
https://youtu.be/r5GRUfizFcI
https://youtube.com/shorts/XcPT185BH...MjYI4rqgWVefLf
TLDR: misfire and rough idle, charts attached in YouTube video, jaguar gods and experts please help me figure this out
Last edited by Barry Leftwich; Oct 22, 2025 at 10:55 AM.
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From: Uk
No, the after-cat sensor is only for catalytic efficiency. The forward sensor is used for air/fuel.
If you have that much fuel, one of your injectors is dumping way too much. That's the only way. Been awhile since I read this thread, can't remember if you checked/changed them.
If you have that much fuel, one of your injectors is dumping way too much. That's the only way. Been awhile since I read this thread, can't remember if you checked/changed them.
Short term fuel trims on both sides were quite even -3 to -10% on bank 2 and -4-5 to -6.5% on bank 1.
as was air flow, injector pulse width too however on the gutted bank that seems to be overfuelling the o2 sensor (pre cat) was double the current (amps) on b1 than b2 when revved only, bank 1 had 630ua and bank 2 had 363ua when revved at the same time it was half on the gutted side.
This ls the only software diagnosis that looked strange, also the post cat o2 sensors were showing 0.11-0.12v stable on the gutted bank 2 but 0.2-0.7v on bank 1. when revved both voltages dropped to 0 / open loop I assume.
this leads me to think it’s the pre cat o2 sensor however I can’t be certain, before I replace does this information tell you anything or would you advise any other checks first? Thank you!
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From: Kaysville, Utah, US
If you don't want to replace the forward sensors just in case, just swap them side to side and see if the fault moves with it or stays put. That will narrow down the parameters.
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From: EU
If the car has seen even one winter, the sensors will be seized and require a massive amount of labor just to remove.
Veteran Member
Joined: Apr 2013
Posts: 11,903
Likes: 6,415
From: Kaysville, Utah, US
Them suckers will come right out. Just don't use a lot of crayon as the wax may foul the sensor.
Mine come right out with a bit of force.
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