Miata MX-5

Engine Misfire Due to Engine Oil on the Spark Plug Wires on Mazda Miata MX-5

Problem Description and Possible Solution

Failure of the valve cover gasket can allow engine oil to leak onto the spark plug wires and damage them. The engine will run poorly (misfire) if the spark plug wires fail.

Problem Data
RepairPal Verified
Average mileage: 140,857 (18,000–240,000)
Engines affected: 1.6L 4 Cylinder, 1.8L 4 Cylinder
10 model years affected: 1990, 1991, 1992, 1993, more1994, 1995, 1996, 1997, 1999, 2000
18 people reported this problem
Viewing 1 - 4 of 4 comments
Valve cover gasket leaking oil into spark plug holes causing misfire. Replaced valve cover gasket.
My check engine light started flashing and it was because oil was leaking into the spark plugs. I stopped driving and got it towed to my mechanic where they were able to replace the valve cover gasket and spark plugs and clean up the system.
Misfire due to plug wire failure causes by valve cover gasket leak.
There has always been an oil leak, since I purchased the car in 2007 with approx 120,000 miles. The leak has gotton worse and most recently became so bad, the car began to misfire, drag, stall and other problems. I had to take it in, and the plugs and wires were drenched in oil and had to be replaced, along with the valve cover gasket. The repair shop proceeded to tell me the valve cover was improperly attached, causing a "pinch", resulting in oil spurting up, and has caused damage to the gasket itself, suggesting that I install a new GASKET. I didn`t. I didn`t have that kind of money. It has been a month, spent close to 500, just to have wires and plugs replaced...and check engine light is on again.