2002 Cylinder Miss-Fire help!!
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Joined: Jan 2014
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From: Charlotte North Carolina
2002 Cylinder Miss-Fire help!!
Hey everyone!!
Needing some help with a miss-firing cylinder.
Car was state inspected and failed with code P0300. State inspection verified that it was cylinder 6. Scanner was put on engine cylinder 6 was confirmed that it was misfiring. Miss fire counts are very rapid about approx 1 per second. Ran diagnostics as per FSM (Factory service manual). Spark was tested at the wire and was ok. Swapped spark plug wire with a good wire and miss fire still occurred on cylinder 6. Swapped ignition coil with a known good cylinder miss-fire still at cylinder 6 only. Ohmed out fuel injector on cylinder 6 was ok with all other injectors just under 14 ohmes. Fuel balanced the injector and it was good also. Swapped injector with another good cylinder and still mis fire on cylinder 6. Swapped all Spark plugs from a good cylinder and miss-fire still occurs. Ran compression test on the right bank all cylinders about 155 PSI after 4 cycles of the engine when it was warmed up. O2 sensors are acting correct but cannot figure out why cylinder 6 has a problem only. 220k miles on the engine.
More info: other cylinder miss fire every so often but nothing like cylinder 6 it's like every second. Says the car is literally running on 7 cylinders.
Needing some help with a miss-firing cylinder.
Car was state inspected and failed with code P0300. State inspection verified that it was cylinder 6. Scanner was put on engine cylinder 6 was confirmed that it was misfiring. Miss fire counts are very rapid about approx 1 per second. Ran diagnostics as per FSM (Factory service manual). Spark was tested at the wire and was ok. Swapped spark plug wire with a good wire and miss fire still occurred on cylinder 6. Swapped ignition coil with a known good cylinder miss-fire still at cylinder 6 only. Ohmed out fuel injector on cylinder 6 was ok with all other injectors just under 14 ohmes. Fuel balanced the injector and it was good also. Swapped injector with another good cylinder and still mis fire on cylinder 6. Swapped all Spark plugs from a good cylinder and miss-fire still occurs. Ran compression test on the right bank all cylinders about 155 PSI after 4 cycles of the engine when it was warmed up. O2 sensors are acting correct but cannot figure out why cylinder 6 has a problem only. 220k miles on the engine.
More info: other cylinder miss fire every so often but nothing like cylinder 6 it's like every second. Says the car is literally running on 7 cylinders.
Last edited by Crontab; Apr 22, 2021 at 10:45 AM.
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Looks like you checked just about everything !!...can you do a crankshaft variation relearn with the scan tool you have ??...if not a shop can do it... only takes a few minutes so it shouldn’t be that expensive...try that !!
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From: Charlotte North Carolina
Thanks for responding C5 Diag!
My tech has a Snap On verus edge scanner we'll see if that can do it, if not we have access to a Bosch Tech II.
FYI: When the engine is reve'd up to about 1.5k -2K Everything evens out and there's no miss fires. Which I get is due to the scanners ability....
Again thanks for the assist!
My tech has a Snap On verus edge scanner we'll see if that can do it, if not we have access to a Bosch Tech II.
FYI: When the engine is reve'd up to about 1.5k -2K Everything evens out and there's no miss fires. Which I get is due to the scanners ability....
Again thanks for the assist!
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You should be able to do it with the Edge...it takes both feet to do the relearn do when it says apply the brake leave it depressed as you accelerate to fuel cutoff !!...keep us informed !!
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Right now I'm waiting on my Snap On guy to get back with me, so we can get a hold of Snap tech to tell me in what "mode" I need to be in, in order for me to perform the relearn. Thanks doood.
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Just go to “engine”under select system (first screen) and on next screen select functional tests and top left should say CKP Variation Relearn !!...this is on my Snap On Verus Pro !!
Last edited by C5 Diag; Apr 22, 2021 at 11:46 AM.
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From: Charlotte North Carolina
Awesome! thanks for the guide!
So followed the instructions and the relearn was successful but 6 is still failing ;-( Everything else is looking good. I'm at a loss on this one.......
So followed the instructions and the relearn was successful but 6 is still failing ;-( Everything else is looking good. I'm at a loss on this one.......
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Hey everyone!!
Needing some help with a miss-firing cylinder.
Car was state inspected and failed with code P0300. State inspection verified that it was cylinder 6. Scanner was put on engine cylinder 6 was confirmed that it was misfiring. Miss fire counts are very rapid about approx 1 per second. Ran diagnostics as per FSM (Factory service manual). Spark was tested at the wire and was ok. Swapped spark plug wire with a good wire and miss fire still occurred on cylinder 6. Swapped ignition coil with a known good cylinder miss-fire still at cylinder 6 only. Ohmed out fuel injector on cylinder 6 was ok with all other injectors just under 14 ohmes. Fuel balanced the injector and it was good also. Swapped injector with another good cylinder and still mis fire on cylinder 6. Swapped all Spark plugs from a good cylinder and miss-fire still occurs. Ran compression test on the right bank all cylinders about 155 PSI after 4 cycles of the engine when it was warmed up. O2 sensors are acting correct but cannot figure out why cylinder 6 has a problem only. 220k miles on the engine.
More info: other cylinder miss fire every so often but nothing like cylinder 6 it's like every second. Says the car is literally running on 7 cylinders.
Needing some help with a miss-firing cylinder.
Car was state inspected and failed with code P0300. State inspection verified that it was cylinder 6. Scanner was put on engine cylinder 6 was confirmed that it was misfiring. Miss fire counts are very rapid about approx 1 per second. Ran diagnostics as per FSM (Factory service manual). Spark was tested at the wire and was ok. Swapped spark plug wire with a good wire and miss fire still occurred on cylinder 6. Swapped ignition coil with a known good cylinder miss-fire still at cylinder 6 only. Ohmed out fuel injector on cylinder 6 was ok with all other injectors just under 14 ohmes. Fuel balanced the injector and it was good also. Swapped injector with another good cylinder and still mis fire on cylinder 6. Swapped all Spark plugs from a good cylinder and miss-fire still occurs. Ran compression test on the right bank all cylinders about 155 PSI after 4 cycles of the engine when it was warmed up. O2 sensors are acting correct but cannot figure out why cylinder 6 has a problem only. 220k miles on the engine.
More info: other cylinder miss fire every so often but nothing like cylinder 6 it's like every second. Says the car is literally running on 7 cylinders.
and head gasket. With 220k 
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Ok, do you see any other cylinders misfiring ??...with the mileage could be worn torque tube couplers...anytime the crank slows down the PCM sees this as a misfire...any vibration can cause this...TT couplers, HB etc... there is a TSB on misfires and TT couplers ...also a compression test isn’t the most accurate way to determine the mechanical health of the engine...don’t know if you can do a cylinder leak down test but that might be useful...maybe you have a wiped cam lobe or lifter issue...an in cylinder pressure transducer test would nail down this issue ...you won’t see this with a compression test !!...also what do your long term fuel trims look like ??...if elevated at idle but decrease at 3000 RPM your looking at a vacuum leak or if the long terms increase as RPM is increased you are looking at fuel delivery or MAF sensor !!...informational video below..this was a worn lobe so you can see with this in cylinder pressure analysis no engine disassembly necessary !!
Last edited by C5 Diag; Apr 22, 2021 at 06:44 PM.
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From: Charlotte North Carolina
Just replaced the torque tube coupler last month on it. Leaning towards an intake manifold or head like the others mentioned. I'll do a leak down test and spray some carb cleaner around and see if I get a response. This is for a state inspection and already have the waver, not going to start down a rabbit hole that is just going to start costing stupid amounts of money to find....at least not yet...
Appreciate all the responses. I'll let you know what the out come is
Appreciate all the responses. I'll let you know what the out come is
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Joined: Sep 2013
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From: Cape Coral, Florida
Just replaced the torque tube coupler last month on it. Leaning towards an intake manifold or head like the others mentioned. I'll do a leak down test and spray some carb cleaner around and see if I get a response. This is for a state inspection and already have the waver, not going to start down a rabbit hole that is just going to start costing stupid amounts of money to find....at least not yet...
Appreciate all the responses. I'll let you know what the out come is
Appreciate all the responses. I'll let you know what the out come is
Just look at your long term fuel trims at idle...if they are high but decrease when you hold the RPM’s at 3000 RPM’s for a few minutes it’s a vacuum leak !!
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Joined: Jan 2014
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From: Charlotte North Carolina
Hey C5 Diag!
Thanks for the response! Questions:
When you say "long term fuel trims at idle...if they are high" what would be considered high?
Vacuum leak....are you saying a vacuum leak in general or to cylinder 6 specifically?
Tanks!
Thanks for the response! Questions:
When you say "long term fuel trims at idle...if they are high" what would be considered high?
Vacuum leak....are you saying a vacuum leak in general or to cylinder 6 specifically?
Tanks!
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From: Cape Coral, Florida
I’d be looking for bank 2 long terms to be high...maybe you have a vacuum leak in the #6 intake runner...thinking about it I’d check for a broken valve spring too...anything over 10% is considered high !!