dv3

what are the chances that my o2 sensors could be bad if the computer isn't showing any codes?
....i failed emissions 3 times now because of high hydrocarbons

....i have changed oil and filter, plugs and wires, used bg 44k fuel additive, did a koeo, koer, and 3 cylinder balance tests ( everything came back ok)

..after "tuning it up" it failed worse ....2.6 vs. 4.6 and 5.0...but runs great

...one other piece of info is the car sat for a long time before this ...only drivin to move occasionally for at least a year...and its a 95 gt

...any chance that its the o2 sensors and the cars computer isn't picking it up?

thanks

Joel5.0

Nope.... Have you run a KOER self test?..... assuming no O2 codes show up, keep in mind that O2 sensors (wideband included) do not measure/check for HC's (unburnt fuel or oil), need to check engine for any misfiring condition, PCV system......

dv3

i did the koer self test using the check engine lights (flashed 9 times)...

...when your say pcv system do you mean i should check my pcv valve?

...i thought high hc only meant unbrunt fuel?..didnt know it wa oil too..i have an oil leak ..the guy i bought it said someone told him it was some kind of seal ...i assume its the rear main seal ...could this be a contributing problem to the emissions?

...it does have a slight misfire (just a very little shake every now and then)...if it was really bad wouldn't the cylinder balance test pick that up?

...i know there are some things that need fixed with this car but i dont want to fix them until it passes emissions ..unless of course it will make it pass emissions ...because i still have time to take the car back for not passing ...i already have over $100 that i wont get back if i cant get it to pass.........where do i start now?

mjr46

misfires will contribute to higher levels of hc, also a malfunctioning evap system can add to high hc's also a since the pcv system draws in crank case vapors that can contribute to high hc's cause remember oil is a pertroleum product from which gas is derived, like I said before a worn motor that has inadequate tension on the oil control rings due to excessive cylinder taper and wear will allow minute amounts of oil into the cumbustion process raising hc's..ect ect.....

dv3

would the cylinder balance test pick this up? ...i dont have a garage right now to do the compression and cylinder leak down test

im going to change the pcv valve today ...and maybe the cap for the misfire?

dv3

reasonable cap and rotor kits ...accel, gold, and mallory range from $20-$55
is there a diffrence ...does it matter?

mjr46

I doubt a cylinder balance test is going to pick up a slight or intermitent misfire

dv3

.....