Last month I was getting awesome gas mileage (22-25mpg city, 25-30mpg highway) and I was stoked! Last week I decided I would change out my fuel filter and PCV valve for basic maintance. I noticed that I had a little more get up and could really get a solid chirp out of second gear on the shift. My dilema is now I get only 17.2mpg city (all tanks are high octane 91+) and only 24mpg on the highway....what the hell is going on...i understand that now more fuel is being pumped into the car with less resistance but a drop of this magnitude seems extreme! I need some advice on what I could check or replace to get my efficiency back close to where it was. Thanks in advance!

-Lieb-

 

Your enjoying the added performance a little to much.

 

yea more performance means heavier on the foot lol but also it could be the ****ty weather out

 

make sure that PCV is the correct one (im sure it is) to get best gas mileage also my MPG dipped after I changed my fuel filter (under 400) ....then on the next tank i got 425+ from there on out....just a suggestion

 

chirping second will do that wouldnt it?

 

I experienced this and diagnosed it as me "testing" out the sweet flow of my Z32 filter.

Even so I ended up at about 24-25mpg mixed driving. Check the usual suspects.

 

Hahaha, Yeah I know that my test of chirping gears is a great reason for the decrease in MPG but I only did that a couple times to, ya know, be sure of the peformance gains. : ) I haven't done a tune up on this car for over 5 years, I'd imagine I need to change out a few more things, right?! My PCV valve is the correct one and is hooked up correctly. Could a new knock sensor be the culprit?! If I'm not throwing any codes what else should I check, besides my driving...

-Lieb-

 

id check spark plugs.. and run some seafoam through the tank and in the intake manifold.. then reset the ecu and see where your at..

 

When was the last time the air filter was changed? How often do you check your tire pressure and what psi do you run the tires at? Have you ever run Chevron Techron or Gumout Regane through the fuel system?

 

Every 0mph to speed limiter kills a mpg for me... But I've never done more than 8 runs on 1 tank before, so I dunno what happens after that.

Last time I changed the fuel filter, I also noticed a decrease in mpg initially, but it went back up after a tank.

Jae

 

I've also noticed 3-5mpg decrease on my 97 SE after installing O2 sensors x 2 and knock sensor. Now the car pulls a bit harder and accelerate a bit better but can it be justified by the 3-5mpg decrease, I thought it suppose to increase by 3-5mpg

 

Yeah, I should've been a little more patient....my MPG are steadily increasing so I'm loosing concern finally....Thanks for all the advice!
-Lieb-