Back some time ago, i ran a whole can of seafoam in a tank of gas <directions say 1/2 can for up to 25 gallons, i run 12>. during that tank of gas, i noticed better sounding exaust, and less dieseling. when i filled up, i also noticed that i only got 7 mpg with the seafoam. i was ticked, but i guess with results comes a price. ever since then, i have noticed a steady drop in fuel mileage, from 14 mpg, to 12 now.


any ideas? air filter was nice and pretty, vacuum system is a mess <always has been though>, and the pcv valve was fine <but no breather filter, until now >. any ideas? it all started with the seafoam...

Any other symptoms other than poor mileage?

Spark plugs were put in 2 weeks ago. old ones were dirty, but i broke one so i replaced them.

car wont run as hard wide open as it will not quite wide open. car runs like crap <outrun by a geo metro crap> after being driven for a while then shut off, but this is all been around since i had the car. doesnt quite seem to have the bite that it used to before the seafoam though.

your cat is clogged

You might be amazed how a bad vacuum system can affect things.

doubt it. just had a high flow installed back in november and a glass pack put on too when i found the back half of the cat in the muffler :?

I'd look at the spark plugs again. Keep them in order so if any look bad you'll know which cylinder they came from.

could the seafoam have killed the o2 sensor?

I second that...if your car was running better after seafoaming it, it probably burnt off a bunch of nasty crap that can screw up your O2 sensor...defineetely a thought.

I wouldnt rule out the clogged cat either, if a bunch of stuff got shook loose inside the engine it could very likely clog up the cat, even if you did have a new one.

Put a scan tool on it see how the O2'* reading.