Disco 2 Misfires
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7th Gear
Joined: Apr 2019
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Disco 2 Misfires
Hey all, Have read about every misfire thread I can track down and need a sanity check.
Currently getting the following codes:
P0300 - RANDOM/MULTIPLE CYLINDER(S) - MISFIRE DETECTED
P0303 - CYLINDER 3 MISFIRE DETECTED
P0305 - CYLINDER 5 MISFIRE DETECTED
Some backstory on the car, 2001 Discovery 2 168k miles non-SAI. I bought it originally in 2017 and drove it until 2019. It started misfiring and the oil light was staying lit a little too long for my comfort when starting up. Sold it to a buddy with the known issues. He drove it 35 miles then it sat parked since. Bought it back late last year with the same misfires and oil light.
Before I sold it I threw 4 new bosch O2 sensors on it, New bosch coils, and some AutoZone special 7mm wires. Misfire persisted. Since getting it back I have replaced the oil pump, and 8 new champion plugs and done some troubleshooting found below. When the original plugs were pulled they were pretty coked up but dry. New plugs on 3/5 smell faintly of old fuel and are damp when removed after running. I haven't been able to run a compression test yet or stick a borescope in 3/5 but those are my next steps unless it seems like I am missing something super obvious here. Could this still be headgasket-related at this point? Or can I semi-safely push that out of my mind?
Troubleshooting done thus far:
Had 2 others verify plug wire routing
Checked for arcing from wires at night - none seen
Tested for spark on 3/5 - Strong arc seen
Moved spark plug wires between cylinders, misfire stays on 3/5
Replaced coil pack with known good coil pack, misfire stays on 3/5
Used a combustion leak tester to see if it may be head gasket related - test indicated the head gasket was intact
Replaced battery with known good battery for testing
Cleaned the single ground strap from the driver's side rear of the engine
Seafoamed and filled up with 93
Currently getting the following codes:
P0300 - RANDOM/MULTIPLE CYLINDER(S) - MISFIRE DETECTED
P0303 - CYLINDER 3 MISFIRE DETECTED
P0305 - CYLINDER 5 MISFIRE DETECTED
Some backstory on the car, 2001 Discovery 2 168k miles non-SAI. I bought it originally in 2017 and drove it until 2019. It started misfiring and the oil light was staying lit a little too long for my comfort when starting up. Sold it to a buddy with the known issues. He drove it 35 miles then it sat parked since. Bought it back late last year with the same misfires and oil light.
Before I sold it I threw 4 new bosch O2 sensors on it, New bosch coils, and some AutoZone special 7mm wires. Misfire persisted. Since getting it back I have replaced the oil pump, and 8 new champion plugs and done some troubleshooting found below. When the original plugs were pulled they were pretty coked up but dry. New plugs on 3/5 smell faintly of old fuel and are damp when removed after running. I haven't been able to run a compression test yet or stick a borescope in 3/5 but those are my next steps unless it seems like I am missing something super obvious here. Could this still be headgasket-related at this point? Or can I semi-safely push that out of my mind?
Troubleshooting done thus far:
Had 2 others verify plug wire routing
Checked for arcing from wires at night - none seen
Tested for spark on 3/5 - Strong arc seen
Moved spark plug wires between cylinders, misfire stays on 3/5
Replaced coil pack with known good coil pack, misfire stays on 3/5
Used a combustion leak tester to see if it may be head gasket related - test indicated the head gasket was intact
Replaced battery with known good battery for testing
Cleaned the single ground strap from the driver's side rear of the engine
Seafoamed and filled up with 93
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