P0300

[sv650steve]

My car has been having a flashing check engine light and misfire as soon as I get on the highway after leaving work. It previously had a P0456. i've been having trouble chasing down the P0456 and it comes on and off, but my car never had any kind of misfire before (tried replacing the gas cap and purge solenoid) condition did not improve. I don't have a clue if these two are related but they did not show up at the same time. The spark plugs are 6 months old. New CPS, and CTS (did not improve misfire). It's also throwing codes for misfire on cylinder 2 and 4. It seems to not get any gas as soon as I rev it but this goes away in around 20 seconds. Gas has been refilled since problem started. Within the last two weeks i de-greased my engine bay and under my gas cap cover. Any ideas?

[CrankyOldMan]

For the P0300, pull the ignition coils off and check for water in the spark plug wells. My son's Echo was misbehaving because the o-rings at the top had failed and were letting water in.

[sv650steve]

I pulled them out and did not feel or see any water on them. I can pull the plugs tomorrow. In the mean time I threw some heet in it incase I got water in my gas (it's been raining alot lately).

[bronsin]

Put the coils from cylinders two and four on cylinders one and three if you now get codes for P301 and P303 those coils are bad.

[sv650steve]

Got a new gas cap and ran heet in it till I could get fresh gas. Problem solved!

[sv650steve]

Update the heet helped but the gas tank was dryrot at the filler neck. I found it with highlighter soaked gas in the tank and a blacklight (no smoke kit) applied rtv. Hopefully that fixes it.