97blackSE

iTrader: (1)

Ok well, I just recently changed my knock sensor, as i was getting an 0304 code that wouldn't go away. The car felt GREAT! All of a sudden, if i was rolling with the clutch engaged fully and i just randomly put the gas to the floor, the car would spin all the way through first, into part of second and then grip (my tires are almost needing new replacement but not quite there)


So everything was good for a few weeks... I was getting 360 miles out of my tank of 93 (bout 24mpg), before my gas light would come on, the car was powerful as hell etc.

Then the other day i get an 0707 code. Rear O2 sensor, this has gone on before, and I have a sensor to put in there, but I'm waiting for an OBX catback to come in the mail for me (should be here in a day or two) Before I bother putting the o2s that i have in. I have a front right bank, and a rear bank sensor,
I just replaced the front left about 2k miles ago, so thats fine.
This tank of 93, i havent done anything differently and all of a sudden, I'm at 1/4 tank with only 220 miles on the trip odometer! Normally at a quarter tank I have closer to 300! what a REDICULOUS loss in gas milage! I had heard that the rear o2 sensor doesnt affect gas milage, and certainly wouldnt affect power, it was only the front bank sensors that did that. I was still getting 340mile per tank with a bad knock sensor, so i dont think its the knock sensor again. I checked the ECU for codes.............0505

I cleaned my TB and IACV not too long ago, after Hearing a weird rhythmic clacking upon popping my hood one morning. It was coming from the IACV, and i was thinking that might be bad, but i havent experienced any weird idle problems at all...the noise is soo weird tho...its not the engine, its like just a slow clack......clack.......clack...it never gets faster or slower, even if i rev the engine... I have never changed PCV, and I DEF. Need New Plugs, And also have an oil change coming up within the next 500 miles.
The exhaust will probably be delivered tomorrow, so I will probably put that on, and the two new O2 sensors in. Hopefully that helps the gas milage, but also, the last few days, my car seems to be slower than $hit. No longer when I mat the gas off the line will it spin, and it just seems to not pull as hard as it was last week... Any theories on what the problem could be? As far as Mods go I only have a popcharger and FSTB!

I'm just not sure wtf the prob could be :weep:
please gimme some ideas im lost, i feel like a

infinitiblast

iTrader: (2)

Actually a friend of mine with a 98 put a apexi ws catback on...his rear o2 sensor had no bung so he tied it up to dangle around until he got the exhaust shop later that week. His gas mileage went way down...he said around 19-20 so yes that rear o2 sensor will affect your gas mileage.

LastBoyScout

a sensor is a sensor. anyone who says that it does nothing lied to you or is very stupid. install that sensor, even if you have to install the new exhaust the next day.

97blackSE

iTrader: (1)

alllllll righty then...The butt dyno still feels as though there is a loss of power too...I really hope that has something to do with the o2 sensors/plugs whatnot..There are still No ghost codes in my ecu. I'm going to put the o2 Sensors in tomorrow...
no time tonite! damn graphic design class! My exhaust Will be in tommorow as well thank god

Would PCV valve maybe be whats clicking in my engine bay btw? Should I change that?

97blackSE

iTrader: (1)

bbbbbbbump

michaelnyden

iTrader: (15)

are the O2 sensors responsible for any for any of the power on our cars?

Dave B

The O2 sensors only operate from idle to 3500rpms.

The only way to accurately calculate gas mileage is to fill the tank COMPELTELY up, clear the tripometer, and when you add gas, you take miles you went and divide by the gallons it took to the fill the tank back to completely full. You can't gauge mpg by just looking at the gas gauge. Even with a 1/4 left, my car go another 70-90 miles before the gas light appears, depending if it's city or highway.

Reasons for poor mpg with no codes:

slow reacting O2 sensors
cold weather (cars consume a lot more gas during warm up)
lead foot
more city driving
under inflated tires
bad gas

Reasons for poor performance with no codes:

temperature (high temps = slower acceleration)
humidity (high humidity = laggy pull)
bad gas
slight vacuum leak



Dave

meccanoble

iTrader: (22)

I used to always get that type of gas mileage, normally ending with between 260 to 290 before gas light comes on. just had front right heated 02 sensor change. Hope mine gets to your high 300 point. How were u driving to get that type of mileage per tank?????

97blackSE

iTrader: (1)

I def. dont drive like a granny but i dont beat the car...Some occasional lead footedness

I usually shift @ like 3500 or so
and get 365 or so from a FULL tank, to when the gas light comes on... and yes dave i was just guestimating, but everytime i fill my tank, I reset the trip-odo so i can keep an eye on gas milage