What systems decide the proper A/F ratio?

I am getting a new primary o2 sensor in hopes of helping my bad mpg. However, people on a local car forum say that the o2 sensor since the early 90's on Hondas has nothing to do with fuel mileage and that only the AF sensor does.

First, I can't find a A/F sensor for the 97 Accord. Secondly, it could be the MAP sensor, which goes off of the EGR readings. So I am assuming my EGR ports are clogged as well. But that job to clean them seems like a bitch. Ugh.

So info to prove the retards wrong would be great! :D

 

Nether the F22B1 nor the F22B2 use an A/F sensor. They both use regular 4 wire narrow band heated O2 sensors. The F23A4 (ULEV) is the one that has the A/F sensor.

The MAP (manifold absolute pressure sensor) Takes it's readings directly from the intake plenum. It sits directly ontop of the throttle body, just after the throttle plate is where it takes it's measurements. Not the EGR system.

Are you having any other problems aside from poor MPG? Anything like a lack of power or a hesitation under load?

 

Thats what I thought. It just uses the o2 sensors.

I am getting roughly 20.2mpg on reg gas and 20.8mpg on pure no ethanol/alcohol gas. It goes up 2 mpg when its warmer out, so obviously the winter blend of gasoline is taking its toll. Sometimes at stop lights it will idle pretty roughly, but other times it wont. And it def. takes more pedal power to get it moving than it used to.

Since its been so cold here you can see the exhaust. It also seems like I am putting out more than other people even after I have had it warmed up for 10 miles or so.

118k miles. Had the free tune up @ Honda at 100k. Only use BP, Shell, or Mobil gas. Change the oil every 3k. Put on new brakes and rotors about 4,000 miles ago.

 

Did they clean out the EGR system. Also you may want to look into cleaning the throttle body, IACV and have a look at injector tips while you have the fuel rail off. If you haven't already. After replacing the O2 Sensor don't forget to reset the ECU.

 

Nope, the o2 sensor is getting replaced Tuesday. None of those have ever been cleaned.

I've seen DIY's, but is it a difficult job for the EGR? It seems like each DIY says you either need new seal or you don't. I haven't even seen DIY's for the throttle body or IACV.

 

If I unclog the EGR ports, do you think it will affect the mpg at all?

Also, should I get any gaskets before I do this?

 

The EGR system isn't really one of fuel savings as it is for emissions control. However, when everything is working as it is supposed to. It could have a positive effect on MPG.

I have always reused my IAC and EGR gaskets, as well as the injector o-rings. But if this is your only car and you want to be sure nothign leaks it would be good to pick up the gaskets and seals before you start the job.

Here are a couple links from the FAQ section,

DIY 94-97 EGR port Cleaning

Cleaning IACV, FITV and Throttle Body Don't bother adjusting the FITV if you are not having any problems with your cold idle.