Help...13-15 MPG In My Ka24de S13

[240sxOwner]

I have cleaned mass air, put in 2 new o2 sensors, new ngk plugs, and new ngk wires...

After all of this my air fuel gauge still reading Very Very Lean, .03 volts from o2 sensor. Is the computer trying to correct for "running lean" therefor dumping fuel into mix? I am getting a reading of .03 volts from the connector of the o2 sensor even with my multimeter. The exhaust smells so rich it actually burns your nose..lol... I need Help

[s13sr20chris]

wow, which wire were you taking that measurement off of? does it run ok? how did the old plugs look? the maf is the biggest single thing controling your fuel so i would start there with a big fuel issue like that.

[240sxOwner]

Ok....my last 10 gallons or so i got about 17....

This is what happened about 3 or 4 weeks before this problem started. I was driving around and my gas light came on and went off. When i see my gas light come on, i never go any more than about 10 miles before refueling. (at this time i was getting 20mpg). After about 6 miles while at a stop light the car started jumping rpm, bobbing is a good description. Then the car shut off....It would start back up but do the same thing...and it would not recognize throttle at all. I put gas in it about 1 hour later and it cranked up good as new.

Even before this i was getting 22-25 city!! But i blew the headgasket, had someone repair it (i was out of state), and on the drive home (all highway) i got about 20mpg. All i know is that i have a vacuum leak near the intake side because i can hear it, but the car runs fine. Every now and then it will scare me because i will be idling and the rpm will lower about 250 without reason....I will be pulling the motor in about 2 months to rebuild it, and i will make sure there are no vacuum leaks

[240sxOwner]

The plugs looked fine...I am tacking the measurement off the female connector on the o2 sensor....It reads .03 and nothing higher.

[ka24e510]

you first mentioned a blown head gasket and then after repair, lower fuel mileage. the coolant has silicates in it and it will damage your o2 sensor. but then you said you replaced it and it wont go above 0.03 volts. this is a big problem. your ecm will see this and dump full rich until it sees the sensor switch. ill give you some things to look for and maybe this will help you find the problem.#1 vacuum leak that is big (usually the car wont run good) if you can hear it, it is leaking.#2 the wire for the 02 sensor is shorted internally (shielded wire) and grounding out the sensor voltage. try to unplug the o2 sensor and check the voltage a 2000 rpm or so, if you get a good reading, but when you plug it back in the reading goes back to 0.03, then this wire is shorted to the grounding meterial inside the wire housing.#3 maf sensor if the car is running lean, it will also probably run poorly but this will cause the o2 sensor to read 0.03 volts (lean condition) but fuel economy will only get really bad when the car starts misfiring or pinging.

if i had to guess, 1 or 2 is more likely. you will have to also consider timing, vacuum line routing, etc... good luck.