that works for coil on plug, not so much for wasted spark, as the spark could be jumping through the wire insulation.
2008 Chevrolet Aveo Misfire uphill (Chevy Again)
- Thread starter robertfixit
- Start date
that works for coil on plug, not so much for wasted spark, as the spark could be jumping through the wire insulation.
- Joined
- Jul 19, 2025
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- 12
I see. I am used to older cars without the "misfire" calculation.
In the meantime, I put the camera on Cyl4 and it is also clean along with the #1. The cross hatching is beautiful, I wonder if the engine was rebuilt because it is unlikely with 120k miles for the head to be so clean. The water theory remains, but would it really leak coolant on all the cylinders? Usually not.
I was going to replace the injectors, but I am not yet confident that is the problem.
Pulled the intake pipe, TB had typical build up nothing abnormal and I cleaned it. The air filter was kind of dirty, but again typical.
After all of that, and monitoring O2 voltage, it is running rich quite a bit even in normal driving. I am starting to wonder if there is a vacuum leak somewhere. When the misfire happens it shows 100% load even though it is only part throttle.
In previous threads people have mentioned EGR valve issues. Considering the misfire happens at a specific load/RPM/throttle position, maybe there is leak there.
I am going to cap off the vacuum line to the EGR and see if that changes anything.
Otherwise, I'm stumped. I do not have a coolant pressure check tool. The car does not overheat. I have had cars with blown head gaskets before and usually you get a stumble at first start in the morning because coolant has seeped into the cylinder.
In the meantime, I put the camera on Cyl4 and it is also clean along with the #1. The cross hatching is beautiful, I wonder if the engine was rebuilt because it is unlikely with 120k miles for the head to be so clean. The water theory remains, but would it really leak coolant on all the cylinders? Usually not.
I was going to replace the injectors, but I am not yet confident that is the problem.
Pulled the intake pipe, TB had typical build up nothing abnormal and I cleaned it. The air filter was kind of dirty, but again typical.
After all of that, and monitoring O2 voltage, it is running rich quite a bit even in normal driving. I am starting to wonder if there is a vacuum leak somewhere. When the misfire happens it shows 100% load even though it is only part throttle.
In previous threads people have mentioned EGR valve issues. Considering the misfire happens at a specific load/RPM/throttle position, maybe there is leak there.
I am going to cap off the vacuum line to the EGR and see if that changes anything.
Otherwise, I'm stumped. I do not have a coolant pressure check tool. The car does not overheat. I have had cars with blown head gaskets before and usually you get a stumble at first start in the morning because coolant has seeped into the cylinder.
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