1999 Saturn SL2 Repair Question
Mileage: 190,000 miles.
What would cause misfire of #2 and #3 cylinders?
Asked by 1999sl2Answer
And the exhaust smells as if it has a lot of unburned fuel. Maybe the downstream O2 sensor has died, so the ECU is cutting spark to cylinders 2 and 3?
No a o2 sensor would not cut out two cylinders bad or not check for spark on number 2 and 3 cylinders.Let me know if you have spark on those two and we will go from there.If you have spark then we need to check compression.Only three things really tie those two cylinders together spark same compression stroke and fuel injectors firing.My money is on spark first then compresson issue.
I checked spark with the 3rd from left plug against the header. No spark. Are the coils the next thing to check? Is there an easy way to swap them?
Voltage on the battery when running is over 14.2, also.
You can swap the coils from left right to right you jut have to take the four bolts out see if the no.spark follows the coil.Let me know what you find.
I swapped the coils, left to right, marking the original left, and the misfire still occurs on #2 and #3 cylinders, confirmed by disconnecting spark and injector wires. Still smells like gas. As you face it, the left coil feeds cylinders 1 and 4. The ignition control module didn't have anything visibly wrong with it.
Are you getting spark from the number 2 and 3 cylinders?If not then you have a bad ignition module.Let me know what you find.
Yesterday, I pulled the #3 spark wire and grounded it against the header: no visible spark, with the engine cranking.
If you have spark on the number 1 and 4 cylinders and not on the number 2 and 3 cylinders and its not the coil then the only other thing left is a bad ignition module.