Misfires under load
Thread Starter
Instructor
Joined: Jan 2018
Posts: 163
Likes: 17
Misfires under load
Hi,
I have a lot of misfires under load
The O2 sensor was bad (stuck at 1048mv) so I changed it yesterday and now it is working
However I still have the misfires whent at WOT
Any Idea ? Do I have to drive the car to reset the ECU value ?
Regards
Richard
I have a lot of misfires under load
The O2 sensor was bad (stuck at 1048mv) so I changed it yesterday and now it is working
However I still have the misfires whent at WOT
Any Idea ? Do I have to drive the car to reset the ECU value ?
Regards
Richard
Le Mans Master
Joined: Jul 2010
Posts: 5,982
Likes: 719
Did this just start out of the blue ?? Or did you do any work on the engine ??
Thread Starter
Instructor
Joined: Jan 2018
Posts: 163
Likes: 17
I did a clutch replacement
The O2 sensor connector was not fitting properly after that so I had to change the entire O2 sensor (car has 70k miles)
I hhad a P0300 and P0134 code
The plugs are brand new, the plug wires also
I swapped the passenger side coils with the driver side coils but same problem
Misfires are mainly located on the driver side cylinders
The O2 sensor connector was not fitting properly after that so I had to change the entire O2 sensor (car has 70k miles)
I hhad a P0300 and P0134 code
The plugs are brand new, the plug wires also
I swapped the passenger side coils with the driver side coils but same problem
Misfires are mainly located on the driver side cylinders
Last edited by Richi; Jan 9, 2021 at 10:26 AM.
Le Mans Master
Joined: Jul 2010
Posts: 5,982
Likes: 719
I did a clutch replacement
The O2 sensor connector was not fitting properly after that so I had to change the entire O2 sensor (car has 70k miles)
I hhad a P0300 and P0134 code
The plugs are brand new, the plug wires also
I swapped the passenger side coils with the driver side coils but same problem
Misfires are mainly located on the driver side cylinders
The O2 sensor connector was not fitting properly after that so I had to change the entire O2 sensor (car has 70k miles)
I hhad a P0300 and P0134 code
The plugs are brand new, the plug wires also
I swapped the passenger side coils with the driver side coils but same problem
Misfires are mainly located on the driver side cylinders
Le Mans Master
Joined: Jul 2010
Posts: 5,982
Likes: 719
I've seen hair line cracks on spark plugs and maybe a spark plugs wire got damaged, seen that also. Ohm out the wire. I'm just tossing so ideas out there. Never know. Just trying to eliminate. 
o another thing is take out all the spark plugs and make sure none are fouled out or soaked with gas.
o another thing is take out all the spark plugs and make sure none are fouled out or soaked with gas.
Last edited by helga203; Jan 9, 2021 at 02:48 PM.
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I've had bad NGK plugs right out of the box. Similar issues to what you're having. If connections are good at the plug and at the coil, you might try another set of plugs. Mine ran fine until I got into boost. Then, it starting with random misfires. I pulled them for inspection and they looked good. Never set a code, but I didn't run them long before going back to AC Delco's one notch colder than stock LS3. Same plugs as used on Z06's and ZR1's. Check everything as mentioned above. If all checks out, find another set of plugs to try. Even the ones you pulled out if they're still around and not fouled.