XPost: alt.home.repair   
   From: csr684@NOTyahoo.com   
      
   micky wrote:   
   > In rec.autos.tech, on Sat, 03 Apr 2021 02:07:24 -0400, "Steve W."   
   >  wrote:   
   >   
   >> Scott Dorsey wrote:   
   >>> micky   wrote:   
   >>>> In rec.autos.tech, on 27 Mar 2021 19:31:15 -0000, kludge@panix.com   
   >>>> (Scott Dorsey) wrote:   
   >>>>   
   >>>>> AK   wrote:   
   >>>>>> I had an oxygen sensor replaced.   
   >>>>>>   
   >>>>>> Prior to that I got 20 mpg in the city for my CX7.   
   >>>>>>   
   >>>>>> Now I am getting 21.5 mpg.   
   >>>>>>   
   >>>>>> Could that increase be due to the replacement of the O2 sensor?   
   >>>>> If your O2 sensor was reading low and causing the computer to run the   
   >>>>> engine too rich, then yes.   
   >>>> So if now I get codes P0171 and P0174, which means that both banks are   
   >>>> running lean, does that mean replacing the sensors will cause the   
   >>>> opposite of what AK had, richer mixturen and decreased mpg?   
   >>   
   >> Changing the sensors will do nothing but show the same codes again.   
   >> Those codes you posted mean the sensors are working. They are seeing   
   >> that there is excess oxygen in the exhaust stream compared to what they   
   >> expect based on the incoming airflow numbers.   
   >> The issue is not them but in the engine. As both are full bank lean   
   >> codes I would look at the fuel trims and the O2 live data and check for   
   >   
   > I did buy a code reader last year that would read the live data, but   
   > what I should look for has been mostly a mystery since then, until the   
   > video below.  I found it a few days ago but just had time to watch it.   
   >   
   > Cars are much more complicated than when I was a boy, or even a   
   > teenager, and I've said for years and told quite a few people that   
   > anyone smart enough to be a good mechanic these days could succeed in a   
   > lot of fields.   
   >   
   >> vacuum leaks or an intake leak that is letting in unmetered air.   
   >> As you don't post any P0300 range codes I doubt it's fuel pressure as   
   >> that will commonly set misfire codes as well as the lean codes.   
   >   
   > Thanks.   I found a long video that went over at least some of the   
   > things to do with a P0171.   https://www.youtube.com/watch?v=SugtR4KMIDU   
   >   
   > He ended up finding a leaky brake booster and a somewhat bad MAF sensor,   
   > but more importantly he goes into some detail about what everything   
   > means.   
   >   
   > You and some of the other people here know everything that is in this   
   > video.  I miss the days when there were people here who knew less than I   
   > do.  They woudl benefit more from this post than you or the others here   
   > will.   
      
   I don't know everything but I'm pretty good at diagnostic and repair   
   work on vehicles.   
      
   How much do you really want to know about modern engine diagnostics?   
      
   --   
   Steve W.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)