gas mileage going down

[mi240sx]

I installed my sr20 det one year ago, it started of getting 24-26 mpg, now I'm getting about 20 mpg. I don't drive hard, bu tI have fun, any ideas.

[MaximA32]

How's you air filter? You running the right tire pressure?

[ZOOMIGUEL]

change pcv valve, and clean fuel injectors

[Q45tech]

Are you one of the luckily areas which has switched to E10? That alone usually reduces MPG by 5% or 1 MPG.

[driftingmy240sx]

the pcv should not effect fuel mileage only crankcase pressures or possible oil consumption.

[supreamS14]

Its usually carbon in the motor or filters or spark plugs even tire pressure has an effect on it! Try 93 octain! already use 93 try fuel injector cleaner or octain boost from NO2! They clame 6 hole octain numbers! Still nothing Try a pro compleat fuel and intake cleaner that will clean out almost any carbon! I would first check the running condishion of the motor ie. fuel pressure, sensors, plugs and electrical connections!

[Q45tech]

Lots of useful technical data can be read from ecu via Consult.Easy to eventually develop injector open times vs flow graphs, same with MAP/MAF voltage readings.

The only way MPG can decrease is too much fuel [richer A/F] or higher rpm.

You can read sensor just as ecu does and think like ecu to solve problem.

How is idle vs cruise vs WOT fuel pressure PSI?