Bad Manifold Gaskets

[Tractor Dan]

Ok. I was pondering this tonight. Is it possible for bad exhaust manifold gaskets to effect your mpg?

The logic i had behind it is this and honestly i'm not even sure if it's all that logical, more or less just something i was pondering tonight. If the manifold gaskets are bad and are allowing exhaust gas to exscape at one or more points upwind of the O2 sensors, then could that cause the sensors to get a false reading? I'm thinking logically if it's allowing exhaust gas to exit before it gets to a sensor or possibly fresh air to enter before the sensor then there could be a false reading to the O2 sensors that would then cause the computer to do what it in theory thinks is the right function even though in reality it's sending too much or too little fuel? Like i said i don't know if there is any merit or logic in this but it's something that came to me tonight.

Also is it possible for a bad manifold gasket to cause a slight misfire? With all the stuff i have done i can still tell there is a slight miss in it somewhere and was just wondering if it might be possible.

Dan

 

[srteach]

Any leak upstream of the O2 sensors will cause mpg or power changes.

 

[Tractor Dan]

Any leak upstream of the O2 sensors will cause mpg or power changes.

Thank you. That's what i was thinking.

Guess i have some looking to do to see if maybe that is where the problem is at.

Dan