MPG?? How much have you got from a tank?

[ptperformance]

OK about 2 or 3 weeks ago I had the check engine light come on (missfire) and I didnt have time to check it out. So during that time of the CEL being on I got very close to 400 mile for one tank of gas. Now I though this was kind of odd since I have been tracking fuel since the start of owning the car. So... I decided to create the missfire again and same thing better gas mileage. Now I have to ask why this happens since I have no idea why having the CEL set would cause better gas mileage. It also seems that the black smoke I get out the back in 2nd gear goes away when the CEL is on. Just thought I would post this up to see if anyone else has seen similar things, thanks.

Forgot to add that after I reset the CEL the next tank of gas gets realy bad MPG (14 to 16) and then it seems to get better over the next few tanks.

 

[AG DesignWorks]

When you were getting those 400 mile tanks, did you have a decrease in performance?

On a road trip, crusing at 75mph on the highway, i've gotten 380 miles out of a tank. That's my best. Usually with day to day driving it's about 300-320 to a tank.

 

[ptperformance]

When you were getting those 400 mile tanks, did you have a decrease in performance?

On a road trip, crusing at 75mph on the highway, i've gotten 380 miles out of a tank. That's my best. Usually with day to day driving it's about 300-320 to a tank.

I didnt really notice any decrease in performance. I got 400 miles and the light had not even came on yet, I suspect that I had another 20 to 40 to go before I ran out of gas but I was really confused with how I got so much more per gallon when the CEL light was on.

 

[redheaddstpch1d]

Depending on how "conservative" I drive, I have gotten anywhere between 250 to 330 miles to a tank(city driving). I managed to get really close to 400 once highway driving.