CrazyIvan1978

I've searched for this, and I've seen various posts on O2 sensor, the P0300 code, and other things. My evo isn't moded, bought it used with 24,400 miles on it in July 2004. Currently have 30,000+ miles on it, had the 30k mile service done at a Mitsu dealer the SES was on during the service and it was an O2 sensor code, so they ordered me a new one. Got the new one installed a week later. Now the SES turns on and off again.

I've noticed that usually if I high rev shift (4~5k RPM) to about 110~120 MPH, then decelerate on 5th gear to about 75 the SES turns on. After about 2 to 3 days it turns off and stays off untill I high rev the car again, or go over 120 MPH. I do not know if the car was ever modded, but it is stock now as far as I can see, dealer hasn't told me otherwise. Also another thing, dealer told me there are two banks of O2 sensors with two each, so 4 total, they replaced one. I also think the car's MPG is below what it should be, usually around 15 MPG. There's a slight increased deceleration when slowly releasing gas pedal around 3k RPM in third and higher gears (I can't explain it except makes my body lurch forward slightly, like a hesitation). When I let go of clutch in idle the car vibrates and makes a noise (probably ****ty TC). Rough idle all around in any condition, but worse with AC on (which I think is probably normal). Please help troubleshoot this SES light thing.

CrazyIvan1978

SES=Service engine Soon btw, for those who are not understanding what I am talking about.

Derek Baker

iTrader: (3)

I'm gonna try to help you out By the way most of us know what a SES light is lol J/k .. I'm thinking that if they just replaced 1 of the O2 sensors that it just might be that you have maybe a slight exhaust leak. The car was probably modded before and that is one of the things that I would check out. Second thing I would check is the plugs. The other thing that you were talking about he deceleration thing well thats normal to me Evo's in general are pretty twitchy when it comes to acceleration / Deceleration, its just the nature of this beast..

Hope that I helped you out some.

Derek

CrazyIvan1978

Exhaust leak...is that something I can check myself, or do I have to take it to a Service Department? If I have to take it to a shop, do you recommend mitsu dealer or a local exhaust specializing shop like Midas for example?

Nad1370

iTrader: (1)

You only have 2 O2 sensors. Bank 1 sensor 1 and Bank 1 sensor 2.

As you described....You either have an exhaust leak like Derek and Ivan stated or have a bad Catalytic Converter.

CrazyIvan1978

Ivan=CrazyIvan1978=dude with the SES light turning on and off=thread starter.
Ok, so there's two O2 sensors, cool. You're saying it could be a bad cat? So, I basically need to take it to Midas or something like that and tell them what I think the problem is, and they can check the exhaust system and hopefully fix it?

boomn29

iTrader: (47)

I know one is in the midpipe, but where is the other??