sadangryboi

95 Civic EX w/94 GSR

Well in my previous thread I had asked why the knock comes on at vtec...well fixed it I guess. Re-wired everything and ran great for about a day. Then the O2 sensor code comes up...it comes on and off at weird times...i did have to extend the wiring for it. Would a o2 sensor going bad cause to throw the CEL on and off at weird times or would the cel be on at all times? And the knock sensor I have no idea....it ran great but it just pops up with the o2 code together. Maybe I have to reset the ecu to clear the codes? Help me out, thanks

Rich

sadangryboi

nobody?

sadangryboi

great!

IHateJDM

your o2 is probably going bad. when the cel comes on, can you turn the car off and restart it without the cel? If so, take it out and clean it with carb cleaner. it'll help until you finally decide to replace it. It could be wiring, that's always a possibility too.

sadangryboi

yea i can tutrn the car off and then turn it back on and itll be gone. weird

IHateJDM

mine does that too. the o2 is on its way out. i've found that it only comes on when the car is warming up. after that, it won't come on. it needs to be replaced, but if you don't have the $, just get carb cleaner and spray the sensor down. it'll buy you a few months.

sadangryboi

sweet..ill do that about the o2...but how come the knock comes on along with it? the knock code only comes up with the o2 code...could it possibly be becuase itll make it run like **** and put the code out?

IHateJDM

does the motor misfire at all when the o2 cel comes on? The knock sensor is just a little microphone that detects vibrations (like detonation), although misfires can sometimes set it off too. It could also not be wired correctly. the ecu usually doesn't look for knock until a certain rpm, so that may be why it's not going off right away.

sadangryboi

its feels sluggish and **** like its flooding/geting no gas/etc

IHateJDM

after the knock cel come on, it'll definitely be sluggish. that will retard your timing and destroy your powerband. how lond does it take to throw the knock cel?

sadangryboi

it only comes on with the o2 light now...so whenever i get the cel its the o2 and knock together....it used to be just knock..but that is fixed so i thought the o2 would b causing it to come on now. it feels sluggish and crap sometimes without a cel like a bad o2...had similiar prob with friends car.....maybe the o2 going bad but not enuff to throw off the ecu a code and when it throws the code...the knock goes up 2?

IHateJDM

does it misfire before it throws the cels? that's the only time I have ever thrown them together. The engine misfired because of the o2 causing too much fuel to be dumped in, and the knock picked up the vibration as if it were detonation. Other than that, I've never seen them only show up at the same time.

sadangryboi

it doesnt missifire...it just feels sluggish like not enuff gas is getting to it sometimes...but most the time its fine...wierd

IHateJDM

i don't know, i'm out of ideas. you said it only happened when the motor is cold though, right? That means that it is a problem in closed loop operation. Closed loop is where the ecu runs off preprogrammed fuel and ignition maps, and doesn't look to the sensors to modify how it's running. Once the engine heats up, and the o2 hits 600 degrees F, then it switches to open loop and the ecu starts doing more. It looks like your problem is in closed loop only. That makes me think: timing (dizzy timing or mechanical timing), wiring, or too much fuel pressure. Good luck man, wish I could help more.

sadangryboi

thanks alot! its alright, ill hopefully figure it out sooner or later...it happens once out of no where...then turn off car and turn it back on and its not there anymore...maybe its the o2 going abd is what i think

thanks alot again for all the help!