Good old IM240, gotta love it. I'm sure this has come up a million times, but I failed the IM240 emmissions test twice, but just barely both times. On the sheet it said .89 hydrocarbons the first time, .93 the second time, I need it to be .80 or lower. Cat is almost brand new, just replaced driver side emissions AIR tube and check valve, brand new platinum spark plugs, always run premium gas and synthetic oil, and I even put in that Bardahl All-U-Need stuff that guarentees passing the test. I cleaned out the throttle body before the test. Only mods are the Flowmaster exhaust and K & N filter. The only thing I can think of that would be wrong would be the O2 sensor, but my gas mileage would be a lot worse if it was bad (17-18/25-27). Any idea's?

 

You could move to Indiana! (no emissions test) LoL . Really, I would try running all that prem. gas out and fill up with 87 octane. The 305 L03 cant make much use of prem. with the low comp. ratio. Make sure initial timing is set at factory specs. Follow timing procedures either on sticker under hood or manual book, unpluging Esc connector is critical to correct initial timing. If you pass the test, you can always change back after certification. Good luck.

 

change the o2 anyway, there cheap and almost allways bad. o2 has to have a freaquency of 9 to 15 hrtz i doo beleive. i may be off on the numbers but i do know that they are almost allways slow with any kind of milage on them. another thing these wonderful cars are known for is the rubber fuel lines by the tank start to emit fuel vapors and causing hc failers