I just bought 03 SI. with 31k on it..had a p0420 CEL going on and off...till recently i started to loose power badly... engine wont go into higher rpms. It starts to make really weird noise like its going to explode... and last time i checked i got another code p0319 engine over speed condition 1 engine over-accelerated 2 vehicle driven too fast 3 if no other codes stored discuss with customer p0420 1catalyc converter defective (FAILURE POSSIBLY) due TO 2engine misfire 3large vacuum leak 4engine oil leakage into exhaust-valve guide seals, piston rings what should i do? its COLD in Ohio.. dont really want to take converter off... i want to be sure... intake got louder!
And you thought it would be a good idea to post this in the 1984-1991 Civic/CRX forums why??? Post in the correct forum, and maybe you'll get an answer...
mine did that once....rpms just get lower and lower. turned out i had spun a rod bearing. It was a 85 sohc engine though. Maybe youll get lucky.