Which is more important for MPG, MAP or O2?

[BoyntonStu]

If you need to modify the signal for MPG improvement and could only choose one, which would you choose and why?

BoyntonStu

[mario brito]

If you need to modify the signal for MPG improvement and could only choose one, which would you choose and why?

BoyntonStu

In my case I would choose the O2 sensor. You can bypass the MAP sensor by putting your intake after it, but not the O2 sensor.

[mario brito]

Update to my answer :

After watching the video ( that you posted the link ) about MAP/MAF sensor's location, I think my answer is not correct.

According to that video, the MAF sensor should be located before the butterfly and the MAP sensor after it. My intake point is just before the butterfly, and after a sensor ( probably MAF ) in the rubber tube that connects the air filter to the engine. In that video, he shows the MAF sensor inside the air filter case. My car doesn't have any sensor there.

So, when I mentioned to be easier to bypass the sensor, I'm probaly talking about the MAF sensor and not the MAP sensor, and that was not your question.

Thanks

[Phantom240]

O2 sensor would be more important on most newer vehicles. Not all vehicles have a MAP sensor (mine, for example). Some vehicles may be easier to modify the MAF signal, through use of an Apex'i SAFC or SAFC-II. Such would be more successful on my car, where a lot of info is available on tuning because many others have used one on their 240sx as well.

[jimbo40]

At this point I'd say o2 sensor. Ive had good results with O2 extenders.
EFEI makes me a little leary, if the EFEI fails, I need 2, I can lose a ECU (computer) in the car. Map enhancers if you lean out the mixture won't your O2 sensors detect the exhuast being lean and richen it up too?
So don't you need EFEI's with a map/maf enhancer?