What we found
We traced the misfire to failing ignition coils. On this engine each cylinder has its own coil-on-plug, and once one or two start to break down the engine runs unevenly and flags a misfire.What we did
Nick replaced the full set of coil-on-plug ignition coils, which meant removing and resealing the intake manifold gaskets to reach them. Doing the whole set at once, rather than one at a time, is what stops the car coming straight back with the next coil failing.How it turned out
The engine ran smooth and even again, with the misfire gone.A rough idle or a stumble with the check engine light on, on a higher-mileage engine, is very often the ignition coils. Replacing the full set together costs a little more up front but saves repeat visits as the others age out.
Prices and times are what this job took on this vehicle. Yours may differ — we will tell you before we start, not after.