misfire 1st gear, '03 Galant

[Inman Lanier]

Howdy, I've got 86K miles, there's a miss in 1st gear under light to moderate acceleration from a stop when hot. Just recently, the check engine light came on (O2 sensor code - bank 1 sensor 1), I replaced the upstream O2 sensor - no change in symptoms.

The car has platinum plugs on it with about 25K miles, so I don't think that's it. When cold, don't notice symptom and fine in other gears so don't think it's wires.

Until now, never had any issues with car other than A/C relief valve pop and stuck open.

Any clues?

[Inman Lanier]

I got some other trouble codes - this time #4 cylinder mis-firing. I decided to change the plug wires (and plugs while I was at it - they only had 19K miles but I thought why not).

The plugs looked perfect so I assume it was the plug wires. I bought the Autolite set that had the 2 wires/boots and the 2 boots (for under the coils).

Car runs perfect again. 86K miles, so be on the lookout. Odd that it was only on throttle tip-in - no other misfiring. I guess that's when it was the leanest (and hardest to fire).