I can't figure out whats wrong, any help is appreciated. I need to resolve this before I waste anymore gas, die of exhaust fumes and possibly cause more damage.

the patient - 2003 g35c 6mt with just intake.

I am trying to figure out what the cause is and how to fix it.
- hopefully not internal engine damage
- replace cats or o2 sensors? ( good justification to buy the high flows)
- wait for ecu to adapt, oil pressure regulate and bad gas to circulate out?

There is no change in the cars handling or power. The throttle response feels better. On the navi I do notice that any mild acceleration makes the mileage drop way down. In order for me to get the mileage to stay above 20mpg I have to be driving way below grandpa speed while barely tapping the gas pedal.

Many things happened in a 2 day span so I can't figure out what may have caused this.

~events~
-Changed oil and accidently put in a 3/4 quart too much (car still averaging 18mpg)
-next day tacking out up to 6th along with 2 other cars (I couldn't call it racing) (still averaging 18mpg)
-later that night filled the car up and put in a bottle of fuel injector cleaner for the first time in the cars life. Reset the navigation and odometer (from then on the readings were very low)

~symptoms~
- I am getting 200 miles per tank averaging at 12mpg freeway and 8mpg street.
- burning smell outside of the car. I'm not sure if it's just from the exhaust
- lots of black soot inside the tail pipe, very strong smell when the car is on
- semi rough idle at the stop light
- check engine light has come on every other day, total of 3 times. 1st time was before the fuel injector cleaner was added.

~actions taken~
- I did drain some oil out and drove around for 100 miles and nothing has changed
- filled up the car with all new gas

 

You need to get the code read for the CEL - that will probably indicate the cause of the problem. If it's come on three times now, there's probably some "real" problem. Try Autozone, they can read the code for you.

 

why did you use injector cleaner? There's absolutely no reason for it, especially if you're using 93 octane gas.....

also....spark plugs! Check them/change them!

could be dirty o2 sensors causing it too.

 

I'd agree with DavesZ#3 that you need the CEL read, but the G35C uses a newer ECU that is not easily read by the universal code readers that places like AutoZone use. The good news is that the codes are stored, but you'll probably need a Nissan CONSULT system to read them out. I'd also reduce my driving if this were my car- the problems you describe could really be screwing up your VQ35DE. Get it repaired before it costs you any more!

 

Are all the codes still retrievable if I did a reset? The light hasn't come on again since I drained the oil, but the mileage is still screwed up and I have the burning smell.

What's the best way to clean a O2 censor? I was told to put a torch to it.

 

Sorry to say, but it sounds like you're trying to do stuff that makes things worse. How did you try to reset the codes? Who told you to use a torch to clean an O2 sensor? Do yourself a favor and take it to a Nissan master tech before you screw up your car any further!

 

Sounds like a bad 02 sensor. The precat ones. Pull the codes as this will tell you exactly were to start.

Also, 3/4 qt overfill? WTF? Get that resolved ASAP if you already haven't

 

yup got the overfill out right away.

I was able to check the right cat o2 sensor. It had a very pretty black velvet fur coat around it, very very rich. I could not easilly get to the o2 sensors on the headers. I found out that the car almost stalls while coming to a complete stop. At this point I'm thinking about just bringing it in for service.

I can't get the cel to come back on.
Any body have tips on how to get the header o2's out?

 

the error message came back.

It was P0171 "Fuel System Lean, Bank 1"

Anyone know what Bank 1 refers to?

 

The 3 cylinders on the drivers side.

Check O2 sensors, injectors, etc......you have a fueling problem on that side.

What is probably happening is it is running lean and dumping fuel to compensate causing your horrible mileage.

 

Thanks JAM!