DaddyMac

12 MPG in a stock N/A means 2 things:

1- can't calculate MPG,

2- engine needs work (tune-up), running rich can cause mileage to go down, but not from the normall 22 highway to 12

CGeek2k

When I bought my car I was looking for 18-25 MPG. The only things I have done to the car are replace the plugs, some of the fluids, and put on a cone filter. I use 5th gear and dont race much so that isnt it. Ill try the injectors and the O2 sensor and see if that helps. Thanks.

Andy

pengaru

are there any drivability issues with the car you have not mentioned which might help us suggest possible problems? run rough when cold, hesitations, lack of power, smoke from exhaust, anything?

mazdaspeed7

For what its worth, I was getting around 22 mpg highway when i had just a cone filter. After full exhaust and a few other mods, it went into the 25-28 mpg range.

CGeek2k

It wont restart about 15 mins after I shut it off. (I think thats flooding) That might be evidence that its the injectors.

It also gives out a small white puff of smoke when I start it. I know that there is a very small leak in the coolant seal, causing it to slowly lose coolant. Im planning on rebuilding the engine next summer to fix that.

Also there is a very slight hesitation around 3500-3800 RPM if it isnt fully warm yet. I dont notice any hesitation after 3-4 miles.

Other than these things the engine runs pretty good, not really powerful but its better than my old truck. Hope this helps.

pengaru

fix those issues and I bet you your mpg will magically go up. First thing imo would be new injectors or have them cleaned, they sound like they are leaking.

mazdaspeed7

Clogged cats possibly?