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02 sensor and better gas mileage



 
 
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  #11  
Old April 8th 21, 03:30 AM posted to rec.autos.tech,alt.home.repair
micky
external usenet poster
 
Posts: 39
Default 02 sensor and better gas mileage

In alt.home.repair, on Wed, 07 Apr 2021 21:50:11 -0400, micky
> wrote:

>In alt.home.repair, on Wed, 07 Apr 2021 20:24:26 -0400, "Steve W."
> wrote:
>
>>Steve W. wrote:
>>> 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,
>>>>>>> (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
>
>I made a lot notes based on what he said.
>
>>>> 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 would 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?

>
>Just enough to fix my car, and maybe a little more. :-)
>
>I used the scanner today and the short and long term trims tracked the
>results of the guy who made the video, at idle and up to 2500rpm. Also


An important thing I left out was that he said "When we raise RPM to
2000, does SHRT get better, or worse, or the same? If it gets better,
lower, usually a vacuum leak."

It got lower for him. And for me, it went up a little at first but then
went down somewhere between quite a bit and a lot. Numbers, if any, are
in the car.

More than one value I saw go in two different directions, and in other
aspects of my life, a little bit in one direction at first and much more
in the other direction soon after. I think he mentioned that too.

So so far it's looking like a vacuum leak.

Maybe no need to replace either 02 sensor, especially the one behind
the engine. OTOH, I've read that they fail with age or miles. 70,000,
100,000 were mentioned and I have 140,000.




>the MAF value (in metric) and the ECT, Spark, Load, and IAT seemed on
>track. Mine starts at OL and goes quickly to CL for both banks.
>
>I forgot to look at the 02BnSn, but I think they're stored in the
>scanner. Yes, I posted them below, if that's what Review refers to.
>
>The scanner is inside with me, but the notes are in the car. I'll post
>them here later.
>
>>Oh where he is checking the hoses, a quick trick is to use carb cleaner
>>and spray it around the hoses. If the engine rpm suddenly jumps look in
>>the area you were spraying for a leak.

>
>He sprayed with water, hoping to hear a hiss, but not with carb clean.
>
>I was going to spray with brake cleaner, because it says No Residue, but
>maybe carb cleaner is better? (He didn't say why not, not a word about
>spraying with other things.)
>
>If that doesn't find it (and I did look everywhere I could think of last
>year, using propane), I'm going to disconnect the purge solenoid and
>plug that hose, and then disconnect the brake booster and plug that one,
>the hoses that go into the throttle body. That's how he found a major
>problem with his brake booster.
>
>He used a vacuum tester to plug each hose in turn that goes to the
>throttle body, but seems to me I don't need a tester. I can assume
>there is some vacuum if the engine is running and it doesn't matter how
>much, and all I need to do is use a pencil or something bigger to plug
>each hose.
>
>Last time when I was trying to find a vacuum leak, I didn't know and
>didn't think about the fact that some leaks don't go to the outside,
>like a leak in a hose does. He didn't name anything other than the
>cannister circuit** and the brake booster that could have an internal
>vacuum leak. There are so many hoses, I dont' have much confidence I
>would think of something else even if it exists. Are there other things
>I should disconnect? **The cannister circuit of couree includes a
>long hose almost to the gas tank, which he couldn't feel or spray or
>look at.
>
>Fixing the brake booster lowered his trim total by 30 points but it was
>still too high. He found that his MAF sensor was off somewhat and after
>he replaced that too, everything was good. (Trim total was between +10
>and -10.) I replaced my MAF sensor about 10,000 miles ago, on the hope
>that would fix things. I only used a mimimal code reader th1en so if it
>made any difference, I don't know, but it didn't get rid of the codes
>and, I doubt if it's the problem now. AND today, I don't want to guess
>what my MAF was at idle, but I know it was 9.5 at 2500RPM. His original
>one started at idle (cold) 0.57 to idle (warm) 1.84, g/sec (and he said
>2 to 3 would be better), but even at 2500 rpm, his value would never go
>over 7 or 8, so I think mine works better. At least I think so.
>
>
>
>I'm not sure what I see when I go to Review / Live Data / Location #1
>(the only one listed). IIUC, the data there is from this afternooon and
>it says
>
>DTC_CNT is 2. That makes sense, P0171 and P0174.
>
>02B1S2(v) is 0.680
> B2 is 0.680 also
>O2B1S1 is 3.279
>02B2S1 is 3.250 very similar to bank 1
> He had said that 3.3 is perfect 14.7 to 1, air to fuel ratio. My
>two numbers are pretty close but maybe they'd be closer to 3.3 if ...
>
>
>EQ_RATB2S1 is 0.988 but I don't know what that means and he didn't say,
>and I havent' taken the time to look it up yet.
> B1S1 is 1.006, very similar.
>
>SHRTFTB1S2 is N/A.
>while
>SHRTFTB2S2 is 99.2 Isn't that strange? In the 4 values 8 lines up,
>B1S2 and B2S2 are exactly the same. there something wrong with B1S2?
>
>02SLOC is B1S12--B2S12-- whatever that means.
>
>
>I hope I didn't give too much info.


Ads
  #12  
Old April 8th 21, 04:43 AM posted to rec.autos.tech,alt.home.repair
micky
external usenet poster
 
Posts: 39
Default 02 sensor and better gas mileage

In alt.home.repair, on Wed, 07 Apr 2021 22:30:04 -0400, micky
> wrote:

>
>>I used the scanner today and the short and long term trims tracked the
>>results of the guy who made the video, at idle and up to 2500rpm. Also

>
>An important thing I left out was that he said "When we raise RPM to
>2000, does SHRT [short term trim] get better, or worse, or the same? If it gets better,
>lower, usually a vacuum leak."


And he said in the video, "If it's worse or the same, it's probably a
fuel delivery or Mass Air flow problem."



>It got lower for him. And for me, it went up a little at first but then
>went down somewhere between quite a bit and a lot. Numbers, if any, are
>in the car.
>
>More than one value I saw go in two different directions, and in other
>aspects of my life, a little bit in one direction at first and much more
>in the other direction soon after. I think he mentioned that too.
>
>So so far it's looking like a vacuum leak.
>
>Maybe no need to replace either 02 sensor, especially the one behind
>the engine. OTOH, I've read that they fail with age or miles. 70,000,
>100,000 were mentioned and I have 140,000.


  #13  
Old April 8th 21, 07:05 AM posted to rec.autos.tech,alt.home.repair
Steve W.[_6_]
external usenet poster
 
Posts: 1,161
Default 02 sensor and better gas mileage

Steve W. wrote:
> Steve W. wrote:
>> 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,
>>>>>> (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?
>>

> Oh where he is checking the hoses, a quick trick is to use carb cleaner
> and spray it around the hoses. If the engine rpm suddenly jumps look in
> the area you were spraying for a leak.
>


From what you posted you have a vacuum leak/pirate air issue as the
primary problem. You can use brake clean or carb cleaner, they are both
more or less paint thinners that burn ok. I use carb cleaner because the
older version of brake cleaner is chlorinated and generates toxic gas
when burned.
The thing to remember though is that in the video he is working on a car
different than yours, some things apply, others don't. For instance MAF
flow, as engine sizes go up, MAF numbers increase even at idle to feed
the larger engine.
Try this
https://support.alldata.com/sites/ma...ing_110918.pdf

Looking at the fuel trims that go up, then start coming down means that
it's a medium sized leak. As the throttle opens it goes past the point
where the pirate air is the main component and the mixture improves. If
it started improving immediately it would be a small leak.

For the sensor data you want to look at it live, and watch what it
actually reads, if the front sensors are changing voltages rapidly as
the engine runs and the rear sensors stay at a somewhat constant number
and don't vary like the fronts, the sensors are working and although
they may be worn, they are doing their job and the converters are working.
You may be surprised at where a vacuum leak can be, brake booster, PCV
system, intake manifold gaskets, a damaged port on the manifold, in the
EVAP system and a host of others, some external others internal.
OH the wuse of water for leaks is somewhat common, it's because you can
use it on a hot or cold engine or one where you have ignition sources
like open plug wires or bad coils. The amount of cleaner you will use
won't be an issue though, just be sure to start on a cold engine.
Usually something like an intake leak will get better as the engine
warms up so you want to catch it when it's cold.


--
Steve W.
  #14  
Old April 9th 21, 03:46 AM posted to alt.home.repair,rec.autos.tech
micky
external usenet poster
 
Posts: 39
Default 02 sensor and better gas mileage

In alt.home.repair, on Thu, 8 Apr 2021 06:37:51 -0700 (PDT), trader_4
> wrote:

>On Thursday, April 8, 2021 at 2:05:17 AM UTC-4, Steve W. wrote:
>> Steve W. wrote:
>> > Steve W. wrote:
>> >> 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,
>> >>>>>> (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?
>> >>
>> > Oh where he is checking the hoses, a quick trick is to use carb cleaner
>> > and spray it around the hoses. If the engine rpm suddenly jumps look in
>> > the area you were spraying for a leak.
>> >

>> From what you posted you have a vacuum leak/pirate air issue as the
>> primary problem. You can use brake clean or carb cleaner, they are both
>> more or less paint thinners that burn ok. I use carb cleaner because the
>> older version of brake cleaner is chlorinated and generates toxic gas
>> when burned.
>> The thing to remember though is that in the video he is working on a car
>> different than yours, some things apply, others don't. For instance MAF
>> flow, as engine sizes go up, MAF numbers increase even at idle to feed
>> the larger engine.
>> Try this
>> https://support.alldata.com/sites/ma...ing_110918.pdf
>>
>> Looking at the fuel trims that go up, then start coming down means that
>> it's a medium sized leak. As the throttle opens it goes past the point
>> where the pirate air is the main component and the mixture improves. If
>> it started improving immediately it would be a small leak.
>>
>> For the sensor data you want to look at it live, and watch what it
>> actually reads, if the front sensors are changing voltages rapidly > the engine runs and the rear sensors stay at a somewhat constant number
>> and don't vary like the fronts, the sensors are working and although
>> they may be worn, they are doing their job and the converters are working.
>> You may be surprised at where a vacuum leak can be, brake booster, PCV
>> system, intake manifold gaskets, a damaged port on the manifold, in the
>> EVAP system and a host of others, some external others internal.
>> OH the wuse of water for leaks is somewhat common, it's because you can
>> use it on a hot or cold engine or one where you have ignition sources
>> like open plug wires or bad coils. The amount of cleaner you will use
>> won't be an issue though, just be sure to start on a cold engine.
>> Usually something like an intake leak will get better as the engine
>> warms up so you want to catch it when it's cold.
>>
>>
>> --
>> Steve W.

>
>Since he's fiddled around looking for a vacuum leak for awhile already and can't
>find an obvious one, I'd suggest getting a schematic that shows all the vacuum lines.


Under the hood is a partial schematic, of thoze hoses related to air
pollution. It doesn't include the brake booster, for example, becauae
I guess that has no effect on air pollution (except when the diaphragm
is broken and they don't count that! Because they only cover what the
law makes them cover.)

It also shows 4 vacuum switching valves, and so far I've only found 3 of
them. But this morning I disconnected the one connected to EVAP,
plugged the tube on the throttle body and it made no change at all in
the fuel trim. I also then disconnected the power brake booster,
plugged the tube, and it made no change in the fuel trim.


This one is very similar to the schematic for my car:
https://www.camryforums.com/forum/at...g-vachose3.jpg
You can click when the cursor ends in + and enlarge the photo.

Can anyone tell me what the rectangle with two hoses ocming out of it
is? It's above the MZ in 1MZ-FE at the bottom left of the picture. And
above the Vacuum Switching Valve that is above that. This part of my car
looks just like this. That is, there is a second VSV, what they label
the PWM Vacuum Switching Valve to the right of that white rectangle (and
if that were bad, they sell a replacement, from Toyota even.)

But the black-outlined white rectangle is just a silver box with two
hoses attached. And two screws holding it to the bracket above the fuel
rail. What does it do?

>Then it will be easier to figure out where they tap off from, how to separate that
>section and plug it.


There are two more hoses connected to the throttle body, neither as easy
to get off. Neither shown to in the diagram they provide. ONe just
goes to the forward valve cover, and iiuc it coudln't be the problem.
The other comes from a 90^ bent tube and I can't tell where it goes. Too
many things in the way.

I'll try to find more stuff about the 3.3L engine. I have the shop
manual for the 3.0L engine from 2000, but those 0.3 liters etc. make a
big difference.

> Or try the smoke tester.


I think we talked about this last year, but I was not despairing yet.
They have one for sale for 100, another for 120, and one for 900. WRT
rental, autozone and advance don't have it, but there was a PepBoys
page, so I called the local Pepboys and he knew almost nothing about it.
I called maybe a bigger Pepboys and he didnt' either but he asked
someone and indded they have such a machine. He didn't even know how
much it costs, but the web page said $30. Well worth it if it works. I
hope they have someone there who stills knows how to use it. And they
want two hours. Maybe more. I guess I can just go and keep busy.


> I've never used one, but have read of
>other people using them and sounds like in principle it would work.


Yes, it does.
>
>
>
>


  #15  
Old April 9th 21, 04:13 AM posted to rec.autos.tech,alt.home.repair
micky
external usenet poster
 
Posts: 39
Default 02 sensor and better gas mileage

In rec.autos.tech, on Thu, 08 Apr 2021 02:05:14 -0400, "Steve W."
> wrote:

>Steve W. wrote:
>> Steve W. wrote:
>>> 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,
>>>>>>> (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?
>>>

>> Oh where he is checking the hoses, a quick trick is to use carb cleaner
>> and spray it around the hoses. If the engine rpm suddenly jumps look in
>> the area you were spraying for a leak.
>>

>
> From what you posted you have a vacuum leak/pirate air issue as the
>primary problem. You can use brake clean or carb cleaner, they are both
>more or less paint thinners that burn ok. I use carb cleaner because the
>older version of brake cleaner is chlorinated and generates toxic gas
>when burned.


Oops, I don't want that. I ordered it online and haven't gotten it yet,
but it also says the original version is not flammable (unlike the other
three versions in green cans, without chlorine),

So how could it work at all if it's not flammable?

There's a chart about a fifth of the way down, comparing 5 different
version of Brakleen. Only in the red can is there chlorine but only that
one is Not Flammable!
https://www.amazon.com/CRC-05089-BRA..._t1_B000BXKZUQ

But in videos I watched, they're using Brakleen in that red can! Life
is so complicated.

>The thing to remember though is that in the video he is working on a car
>different than yours, some things apply, others don't. For instance MAF
>flow, as engine sizes go up, MAF numbers increase even at idle to feed
>the larger engine.


Yes, I see. The engine he's working on is only 4 cylinders. Mine is 6.
>Try this
>https://support.alldata.com/sites/ma...ing_110918.pdf


I'll print this and do as he says tomorrow.
>
>Looking at the fuel trims that go up, then start coming down means that
>it's a medium sized leak. As the throttle opens it goes past the point
>where the pirate air is the main component and the mixture improves. If
>it started improving immediately it would be a small leak.


Yes, I see.

>For the sensor data you want to look at it live, and watch what it
>actually reads, if the front sensors are changing voltages rapidly as
>the engine runs and the rear sensors stay at a somewhat constant number
>and don't vary like the fronts, the sensors are working and although
>they may be worn, they are doing their job and the converters are working.
>You may be surprised at where a vacuum leak can be, brake booster, PCV
>system, intake manifold gaskets, a damaged port on the manifold, in the
>EVAP system and a host of others, some external others internal.


I'll keep looking and look again at places I've looked.

>OH the wuse of water for leaks is somewhat common, it's because you can
>use it on a hot or cold engine or one where you have ignition sources
>like open plug wires or bad coils. The amount of cleaner you will use
>won't be an issue though, just be sure to start on a cold engine.
>Usually something like an intake leak will get better as the engine
>warms up so you want to catch it when it's cold.


Okay.
  #16  
Old April 9th 21, 07:01 AM posted to rec.autos.tech,alt.home.repair
Steve W.[_6_]
external usenet poster
 
Posts: 1,161
Default 02 sensor and better gas mileage

micky wrote:
> In rec.autos.tech, on Thu, 08 Apr 2021 02:05:14 -0400, "Steve W."
> > wrote:
>
>> Steve W. wrote:
>>> Steve W. wrote:
>>>> 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,
>>>>>>>> (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?
>>>>
>>> Oh where he is checking the hoses, a quick trick is to use carb cleaner
>>> and spray it around the hoses. If the engine rpm suddenly jumps look in
>>> the area you were spraying for a leak.
>>>

>> From what you posted you have a vacuum leak/pirate air issue as the
>> primary problem. You can use brake clean or carb cleaner, they are both
>> more or less paint thinners that burn ok. I use carb cleaner because the
>> older version of brake cleaner is chlorinated and generates toxic gas
>> when burned.

>
> Oops, I don't want that. I ordered it online and haven't gotten it yet,
> but it also says the original version is not flammable (unlike the other
> three versions in green cans, without chlorine),
>
> So how could it work at all if it's not flammable?
>
> There's a chart about a fifth of the way down, comparing 5 different
> version of Brakleen. Only in the red can is there chlorine but only that
> one is Not Flammable!
> https://www.amazon.com/CRC-05089-BRA..._t1_B000BXKZUQ
>
> But in videos I watched, they're using Brakleen in that red can! Life
> is so complicated.
>
>> The thing to remember though is that in the video he is working on a car
>> different than yours, some things apply, others don't. For instance MAF
>> flow, as engine sizes go up, MAF numbers increase even at idle to feed
>> the larger engine.

>
> Yes, I see. The engine he's working on is only 4 cylinders. Mine is 6.
>> Try this
>> https://support.alldata.com/sites/ma...ing_110918.pdf

>
> I'll print this and do as he says tomorrow.
>> Looking at the fuel trims that go up, then start coming down means that
>> it's a medium sized leak. As the throttle opens it goes past the point
>> where the pirate air is the main component and the mixture improves. If
>> it started improving immediately it would be a small leak.

>
> Yes, I see.
>
>> For the sensor data you want to look at it live, and watch what it
>> actually reads, if the front sensors are changing voltages rapidly as
>> the engine runs and the rear sensors stay at a somewhat constant number
>> and don't vary like the fronts, the sensors are working and although
>> they may be worn, they are doing their job and the converters are working.
>> You may be surprised at where a vacuum leak can be, brake booster, PCV
>> system, intake manifold gaskets, a damaged port on the manifold, in the
>> EVAP system and a host of others, some external others internal.

>
> I'll keep looking and look again at places I've looked.
>
>> OH the wuse of water for leaks is somewhat common, it's because you can
>> use it on a hot or cold engine or one where you have ignition sources
>> like open plug wires or bad coils. The amount of cleaner you will use
>> won't be an issue though, just be sure to start on a cold engine.
>> Usually something like an intake leak will get better as the engine
>> warms up so you want to catch it when it's cold.

>
> Okay.


If you like visit 2carpros.com Put in as much info about your issue as
you can and one of the crew can look up the line routing and parts on
that car and give you much more info including pictures and other tests.

--
Steve W.
 




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