vassago

iTrader: (1)

a couple months ago i got the buschur racing stage 1 (with the hfc and bullet muffler) and a walbro 255lph fuel pump. i installed everything and have had a cel ever since. the first time i pulled the code it was just the p0420. but recently i also got a p0300. sometimes the cel will just go away and sometimes it's on for weeks at a time (i don't have an obdII reader, so i can't check and clear the codes constantly). what would cause the p0300? the only other engine mod i have is an hks ssqv ricer valve recirculated to the intake. also, for the p0420, since i have a tune shouldn't that take care of 02 sensor readings? the car seems to run good (idles a little high), and pulls strong. i'm happy with it, but can't pass emission with a cel and am now worried because the p0300.

lcwjr

iTrader: (4)

There's a lot of info about those two codes in this forum. Search...try "cel fix". In answer to your question about code P0420, a tune will not remove or correct the code. Your hi-flow cat is causing the rear O2 sensor to trip the code. You will need to move that sensor out of the exhaust flow a little with an adapter. Until you do this, you can clear the code, but it will keep coming back. Search, and you will see what I mean. Do yourself a favor, and buy or borrow an OBD II scanner. It will make make it easy to read and clear any codes.

delongedoug

iTrader: (20)

Do some searches. Both of these have been covered ad nauseum.

If you can't bypass the P0420 via the ECU, try this:

https://www.evolutionm.net/forums/ev...ouler-how.html

For the P0300, there is a fix thread on here somewhere but I don't have that one bookmarked. Change your sparkplugs if you haven't in a while.

YMMV