Exhaust Experiments & Air Fuel Ratio

[dkjones96]

Originally Posted by ProtonXX

I did an unconventional experiment when I accidentally broke my exhaust nuts & couldn't screw the pipe on. This led me to drive 360 miles without a midpipe, cat & muffler.

The result was the best gas mileage ever. I drove 330 miles before the gas light came on. My previous best was 315.

I put on a highflow cat but took it off because it had a severe drop in mileage. But when I take the whole thing off my mileage goes up..hmm so now its time to tamper with the 2nd O2 sensor.

Its something I don't want to duplicate again but it led me to do to 2 different tests to try out.
The problem with my car is if u lean the fuel too much the 2nd O2 sensor picks it up because theres no gas to burn in the cat. Its all got burned in the more efficient A/F ratio. The 2nd sensor mimics the first sensor & inefficient CAT cel (p0420) is given robbing mileage again

If you take the whole thing off the second O2 sensor will pick that up too. So how does leaning out the engine throw a check code but not having the exhaust on at all doesn't?

[kamesama980]

KYLE!!!! I didn't know you were on here too. What's up buddy?

[ProtonXX]

Originally Posted by dkjones96

If you take the whole thing off the second O2 sensor will pick that up too. So how does leaning out the engine throw a check code but not having the exhaust on at all doesn't?

I have no idea. The check engine light came on after the 2nd tank but the mileage dropped low then.

[ProtonXX]

1st tank done. 270 Miles...9.4 Gallons Fillup...27 MPG.

I wired everything wrong so basically I didnt have a 2nd O2 sensor & my original cat pipe on. This time Ill hook up the wires right & see how it goes.

I spent all tank resetting the check engine light too.

[ProtonXX]

Things are looking up. Way up. Scan gauge looks happy & was reporting 70mpg at 40mph cruise. My fuel ratio stayed low & no Check engine light.

Current config is.
Rear O2 Simulator + Bright Green on light lean trim EFIE
Front O2 Sensor + Bright green EFie on a hard lean trim.


If things work out Ill switch to the highflow cat & see where it goes. I dont expect less than 30mpg

[ProtonXX]

No 30 mpg

Check engine light came on less but it still appeared a few times. Around The same mileage too but the A/F ratio was sticking longer. It wasn't re adjusting to 14.7 levels except around the times the CEL coming on.

last test is the O2 Sensor defouler. O2 Sensor Simulator & Efie are off the rear plug again. Lets see how it go