Misfire & coil codes plus restricted performance... Oxygen sensor???
#1
Misfire & coil codes plus restricted performance... Oxygen sensor???
I'm getting restricted performance flashes at around 2k rpm while decelerating, occasional CEL with misfire or coil codes in bank 1 only (1,4,6,7 coil set). Long term trims are right around zero and short term trims are no more than -6% when CEL comes on. Both bank 1&2 fuel trims are exactly the same (less than 1% deviation). There is no perceptible loss of performance or idle smoothness. CEL goes away after a few starts. Only happens with engine warmed up and after many miles driven usually 20+. 87,000 miles on odometer.
Sparkplugs and coils are new and I've moved them around so it's not that. Tested coil wiring and it all tests good. Fuel trims suggest no problem with fuel delivery...? (usually cylinder 6 flags first... One bad or leaking injector? Sometimes cylinder 4 flags first, both in same bank 1 though). No fuel smell from exhaust.
In really thinking my bank 1 upstream oxygen sensor is the culprit. No flags from the sensor but that wouldn't be the first time a Jaguar threw codes that didn't exactly match the problem. The fuel trims are what lead me to think thusly. The banks match and 6% is still in the good range for short term, right?
I'd love to hear what ya'll have to say before I spend 200 bucks for one sensor.
Sparkplugs and coils are new and I've moved them around so it's not that. Tested coil wiring and it all tests good. Fuel trims suggest no problem with fuel delivery...? (usually cylinder 6 flags first... One bad or leaking injector? Sometimes cylinder 4 flags first, both in same bank 1 though). No fuel smell from exhaust.
In really thinking my bank 1 upstream oxygen sensor is the culprit. No flags from the sensor but that wouldn't be the first time a Jaguar threw codes that didn't exactly match the problem. The fuel trims are what lead me to think thusly. The banks match and 6% is still in the good range for short term, right?
I'd love to hear what ya'll have to say before I spend 200 bucks for one sensor.
#2
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Victor Marquez (04-01-2021)
#3
#4
Have you tried testing injectors 4 & 6, both the wiring to them and the injectors themselves? Swopping them out?
My injectors numbered 7 & 8 became somewhat intermittent before (this at different times) failing altogether?
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Victor Marquez (04-01-2021)
#5
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Victor Marquez (04-01-2021)
#6
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Victor Marquez (04-01-2021)
#7
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#8
HERE IS MY ORIGINAL POST CORRECTED
I'm getting restricted performance flashes at around 2k rpm while decelerating, occasional CEL with misfire or coil codes in bank 2 only (cylinders 4 & 6). Long term trims are right around zero and short term trims are no more than -6% when CEL comes on. Both bank 1&2 fuel trims are exactly the same (less than 1% deviation). There is no perceptible loss of performance or idle smoothness. CEL goes away after a few starts. Only happens with engine warmed up and after many miles driven usually 20+. 87,000 miles on odometer.
Sparkplugs and coils are new-ish (not originals) and I've moved them around so it's not that. Tested coil wiring and it all tests good. Fuel trims suggest no problem with fuel delivery...? (usually cylinder 6 flags first... One bad or leaking injector? Sometimes cylinder 4 flags first, both in same bank 2 though). No fuel smell from exhaust.
I'm really thinking my bank 2 upstream oxygen sensor is the culprit. No DTC from the oxygen sensor but that wouldn't be the first time a Jaguar threw codes that didn't exactly match the problem. The fuel trims are what lead me to think thusly. The banks match and 6% is still in the good range for short term, right?
I'd love to hear what ya'll have to say before I spend 200 bucks for one sensor.
I'M ALSO POSTING THIS DIAGRAM, THIS IS MY UNDERSTANDING OF HOW THE CYLINDERS ARE DIVIDED ELECTRONICALLY.
THANK YOU FOR HAVING TAKEN THE TIME TO ANSWER AND FOR YOUR PATIENCE WHILE I SORTED OUT THE MISTAKES I MADE.
I'm getting restricted performance flashes at around 2k rpm while decelerating, occasional CEL with misfire or coil codes in bank 2 only (cylinders 4 & 6). Long term trims are right around zero and short term trims are no more than -6% when CEL comes on. Both bank 1&2 fuel trims are exactly the same (less than 1% deviation). There is no perceptible loss of performance or idle smoothness. CEL goes away after a few starts. Only happens with engine warmed up and after many miles driven usually 20+. 87,000 miles on odometer.
Sparkplugs and coils are new-ish (not originals) and I've moved them around so it's not that. Tested coil wiring and it all tests good. Fuel trims suggest no problem with fuel delivery...? (usually cylinder 6 flags first... One bad or leaking injector? Sometimes cylinder 4 flags first, both in same bank 2 though). No fuel smell from exhaust.
I'm really thinking my bank 2 upstream oxygen sensor is the culprit. No DTC from the oxygen sensor but that wouldn't be the first time a Jaguar threw codes that didn't exactly match the problem. The fuel trims are what lead me to think thusly. The banks match and 6% is still in the good range for short term, right?
I'd love to hear what ya'll have to say before I spend 200 bucks for one sensor.
I'M ALSO POSTING THIS DIAGRAM, THIS IS MY UNDERSTANDING OF HOW THE CYLINDERS ARE DIVIDED ELECTRONICALLY.
THANK YOU FOR HAVING TAKEN THE TIME TO ANSWER AND FOR YOUR PATIENCE WHILE I SORTED OUT THE MISTAKES I MADE.
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motorcarman (03-24-2021)
#9
I replaced the sparkplugs and coils when the coils started failing, they were the originals. I replaced the sparkplugs with the correct NGK IFR5N10 and the new coils are Bremi. It had nothing to do with the problem I'm having now. The reason why I don't think it's the injectors is because my idle is smooth and I'm getting no perceptible misfiring. When the restricted performance light flashes it only flashes for a second, then stops, right around 2k rpm but there is no loss of performance whatsoever.
#10
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Victor Marquez (04-01-2021)
#11
One thing you cannot hear, when listening to injectors, is if there is a slight leak. Fuel is cut off when decelerating with foot completely off throttle. A leak will possibly be recorded as a misfire since the leaking injectors may produce power and throw off the cam timing signal that indicates misfire.
Try deceleration with a tiny bit of throttle and see if you get the same fault.
Try deceleration with a tiny bit of throttle and see if you get the same fault.
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Victor Marquez (04-01-2021)
#12
Have had something similar on a 1997 XK8. Faults on coils 2,3,5 and 8 (two on each bank) but also had fault: P1368 Ignition group 2 defective. Not sure how this problem started as I don't know the history of the car but likely with faults on one coil.
Turned out to be leaking capacitor in the ECM and made some damage inside the computer.
Have replaced XK8 computers in the past, haven't done it (yet) on a X350 but faults looks similar. Not saying this is your problem but keep it in mind as it looks like your ignition group 1 is failing.
Turned out to be leaking capacitor in the ECM and made some damage inside the computer.
Have replaced XK8 computers in the past, haven't done it (yet) on a X350 but faults looks similar. Not saying this is your problem but keep it in mind as it looks like your ignition group 1 is failing.
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Victor Marquez (04-01-2021)
#14
#15
One thing you cannot hear, when listening to injectors, is if there is a slight leak. Fuel is cut off when decelerating with foot completely off throttle. A leak will possibly be recorded as a misfire since the leaking injectors may produce power and throw off the cam timing signal that indicates misfire.
Try deceleration with a tiny bit of throttle and see if you get the same fault.
Try deceleration with a tiny bit of throttle and see if you get the same fault.
#16
Have had something similar on a 1997 XK8. Faults on coils 2,3,5 and 8 (two on each bank) but also had fault: P1368 Ignition group 2 defective. Not sure how this problem started as I don't know the history of the car but likely with faults on one coil.
Turned out to be leaking capacitor in the ECM and made some damage inside the computer.
Have replaced XK8 computers in the past, haven't done it (yet) on a X350 but faults looks similar. Not saying this is your problem but keep it in mind as it looks like your ignition group 1 is failing.
Turned out to be leaking capacitor in the ECM and made some damage inside the computer.
Have replaced XK8 computers in the past, haven't done it (yet) on a X350 but faults looks similar. Not saying this is your problem but keep it in mind as it looks like your ignition group 1 is failing.
#18
Hey, I've only done visual, cursory checks for vacuum leaks. Spraying carb cleaner doesn't seem to do much on these jags. Most of the tough vacuum problems seem to be coming from the intake manifold, so I might end up doing a smoke test.
#19
As mentioned by motorcarman, bank 1 is 1,3,5,7 and bank 2 is 2,4,6,8.
Have you tried testing injectors 4 & 6, both the wiring to them and the injectors themselves? Swopping them out?
My injectors numbered 7 & 8 became somewhat intermittent before (this at different times) failing altogether?
Have you tried testing injectors 4 & 6, both the wiring to them and the injectors themselves? Swopping them out?
My injectors numbered 7 & 8 became somewhat intermittent before (this at different times) failing altogether?
#20
Hi Victor,
I had a similar issue some time ago now. I was getting misfires on one cylinder and they got worse and worse, car was juddering and lurching and ended up flashing the CEL with misfire codes. My problem was a failing injector. They seem to start to fail and cause intermittent misfires and mine did not throw any fault codes for the actual injector until it finally threw an open circuit fault.
I then had the same symptoms on another cylinder and installing a new injector fixed that problem as well.
You can firstly test the OHMs of the injector to see if you are getting the correct readings. You should get a reading of around 14.9 and they should be a steady and constant reading. If you are getting fluctuating OHMs readings when you test for a period of time or you get no readings at all or you get a reading of 1 (meaning open circuit) then you have a faulty or failing injector on that cylinder.
I helped EsRay in this thread (post 2 and 6) which I described how to test the injector on the cylinder that is reporting the fault.
Thanks,
Chris
I had a similar issue some time ago now. I was getting misfires on one cylinder and they got worse and worse, car was juddering and lurching and ended up flashing the CEL with misfire codes. My problem was a failing injector. They seem to start to fail and cause intermittent misfires and mine did not throw any fault codes for the actual injector until it finally threw an open circuit fault.
I then had the same symptoms on another cylinder and installing a new injector fixed that problem as well.
You can firstly test the OHMs of the injector to see if you are getting the correct readings. You should get a reading of around 14.9 and they should be a steady and constant reading. If you are getting fluctuating OHMs readings when you test for a period of time or you get no readings at all or you get a reading of 1 (meaning open circuit) then you have a faulty or failing injector on that cylinder.
I helped EsRay in this thread (post 2 and 6) which I described how to test the injector on the cylinder that is reporting the fault.
Thanks,
Chris
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Victor Marquez (07-14-2021)