Bad mpg

[BLINKY619]

Ok people my car runs fine just did maintenance and still runs rich i mean ive done a lot to it even made a boost leak test didn't find any i had one but fixed it weeks ago it was the shaft seals i get really bad gas millage 2-3 days and empty's full tank im comfused no check engine light or codes...!

 

[gingerbredman00]

Do you have an aftermarket fuel pump?

 

[Boomdeeze]

Yes he has a rewired 255 walbro, it says so in his profile.

 

[spyderturbo007]

You'll want to start by taking a look at your front O2 sensor. Have you ever replaced it before? Do you have a logger? If not, you can use a volt meter and probe the wire.

 

[BLINKY619]

NO I DONT HAVE A LOGGER AND HOW CAN I CHECK IT WITH A VOLT METER? WHAT SHOULD I SET MY AFPR ON CAUSE ITS ON 43 PSI RIGHT NOW...! is that right? how can i know if my o2 sensor is bad when its not throwing any codes? thanks for the help

 

[spyderturbo007]

You'll want the AFPR set to 43.5psi with the vacuum line disconnected. Probe the signal wire on the O2 sensor with a volt meter, or you can check at the ECU using pinout #76. At idle it should be oscillating between about 0.2v and 0.8v. If it isn't then the sensor is shot.

A dead O2 sensor won't throw a code right away, but will when the FT's are maxed out. It's possible that it's dying and just inflating your FT's with a false lean condition which won't throw a code.

You might also want to take a look at your coolant temp sensor, although I have no idea how to check that without a logger. Perhaps someone can take a look at the service manual for a diagnostic procedure, because I don't have one in front of me right now.

 

[BLINKY619]

ALRIGHT thanks for the help yea my coolant temp. sensor is new

i dont have my cas connected yet i haven't done the mod yet could that be causing my bad gas mileage