Random missfire both sides
Thread Starter
Pro
Joined: Sep 2013
Posts: 512
Likes: 10
Random missfire both sides
2001 ls1 6.0 ck2500 truck
random misfires on both banks. Random cylinders.
Runs rough at idol.
around 115k> changed plugs and wires around 100k. Believe i installed acdelco oem plugs.
Should I replace all O2 sensors? I cleaned throttle body and MAF sensor already.
random misfires on both banks. Random cylinders.
Runs rough at idol.
around 115k> changed plugs and wires around 100k. Believe i installed acdelco oem plugs.
Should I replace all O2 sensors? I cleaned throttle body and MAF sensor already.
Race Director
Joined: Apr 2017
Posts: 10,247
Likes: 888
From: Hickory NC
2025 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
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St. Jude Donor '17 thru '26
There are a lot of different things that could be causing this, and you’re correct that the O2 sensors could be the culprit, but there are many other things that could cause this.
The first suggestion, though, is to try and check the engine with a diagnostic tool that will plug in to your OBDII port. This will at least get you in the ball park. AutoZone, Pep Boys, NAPA, Advance Auto, or other comparable stores usually have diagnostic tools that might help you isolate the problem.
Check your plugs. If the O2 sensor is bad, typically it will change the air/fuel ratio and foul some or all of the plugs. A bad catalytic convertor can affect your O2 sensors.
Additionally, vacuum leaks, bad fuel injectors, a dirty fuel filter, or even other issues could be the culprit.
Again, a good diagnostic test is your best first start.
Good luck.
The first suggestion, though, is to try and check the engine with a diagnostic tool that will plug in to your OBDII port. This will at least get you in the ball park. AutoZone, Pep Boys, NAPA, Advance Auto, or other comparable stores usually have diagnostic tools that might help you isolate the problem.
Check your plugs. If the O2 sensor is bad, typically it will change the air/fuel ratio and foul some or all of the plugs. A bad catalytic convertor can affect your O2 sensors.
Additionally, vacuum leaks, bad fuel injectors, a dirty fuel filter, or even other issues could be the culprit.
Again, a good diagnostic test is your best first start.
Good luck.
Thread Starter
Pro
Joined: Sep 2013
Posts: 512
Likes: 10
There are a lot of different things that could be causing this, and you’re correct that the O2 sensors could be the culprit, but there are many other things that could cause this.
The first suggestion, though, is to try and check the engine with a diagnostic tool that will plug in to your OBDII port. This will at least get you in the ball park. AutoZone, Pep Boys, NAPA, Advance Auto, or other comparable stores usually have diagnostic tools that might help you isolate the problem.
Check your plugs. If the O2 sensor is bad, typically it will change the air/fuel ratio and foul some or all of the plugs. A bad catalytic convertor can affect your O2 sensors.
Additionally, vacuum leaks, bad fuel injectors, a dirty fuel filter, or even other issues could be the culprit.
Again, a good diagnostic test is your best first start.
Good luck.
The first suggestion, though, is to try and check the engine with a diagnostic tool that will plug in to your OBDII port. This will at least get you in the ball park. AutoZone, Pep Boys, NAPA, Advance Auto, or other comparable stores usually have diagnostic tools that might help you isolate the problem.
Check your plugs. If the O2 sensor is bad, typically it will change the air/fuel ratio and foul some or all of the plugs. A bad catalytic convertor can affect your O2 sensors.
Additionally, vacuum leaks, bad fuel injectors, a dirty fuel filter, or even other issues could be the culprit.
Again, a good diagnostic test is your best first start.
Good luck.
Burning Brakes
Joined: Feb 2013
Posts: 904
Likes: 296
From: Sacramento, California
The reason I mentioned this is because I was getting a random misfire code on my 02Z even though it only had 12k miles. When I pulled the plugs to check for cracks or broken electrodes I found the gaps ranged from .055 to .060. After I installed new iridium plugs gapped to .040 the misfires went away. Maybe just pull a few of the easy to reach plugs and double check gaps?
Steve
Steve
Thread Starter
Pro
Joined: Sep 2013
Posts: 512
Likes: 10
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Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Check the coil circuit ground on the rear of the drivers head and make sure it clean and tight.
Then, Check the voltages at the coil circuit fuses to amke sure that all the fuses are getting full battery voltage. Test the fuse test slots on top of the fuses to chassis ground. The KEY ON fuses shoukd see 00% battery voltage.
Low voltage is not good on the coil circuits.
coils 2 & 4
coils 5& 7
Then, Check the voltages at the coil circuit fuses to amke sure that all the fuses are getting full battery voltage. Test the fuse test slots on top of the fuses to chassis ground. The KEY ON fuses shoukd see 00% battery voltage.
Low voltage is not good on the coil circuits.
coils 2 & 4
coils 5& 7