Jump to content


O2 Sensors - Dual Exhausts


  • Please log in to reply
15 replies to this topic

#1 _SLY HR_

_SLY HR_
  • Guests

Posted 29 June 2015 - 07:25 PM

Howdy All,

 

Just trivial discussion here.

I have noticed O2 sensor manufacturers listing both single and dual packages, listed as for V configuration engines with twin exhausts as to monitor AFR's from both cylinder banks.

However, on many occasions I have just seen a V configuration engine with only one sensor, prior to a collector or X-pipe.

Would there be any noticeable gain in having a sensor for each bank as opposed to only reading AFR's from a single bank?
How would this situation apply to an inline 6 which has a dual exhaust with no X-pipe?

 

Cheers,

Josh



#2 yel327

yel327

    Oh My, Don't you post alot

  • Members
  • PipPipPipPipPipPipPip
  • 13,009 posts
  • Joined: 10-February 08

Posted 29 June 2015 - 07:29 PM

I've noticed over the years that VN-VS V8 engines have one sensor and the sequentially injected VS3 (and VT) engines have two. So more than likely you need one in each bank for sequentially injected engines and only the one for batch fired systems?



#3 TerrA LX

TerrA LX

    Fulcrum Fixture

  • Members
  • PipPipPipPipPipPipPip
  • 14,241 posts
  • Location:Sid 'n' knee
  • Joined: 31-May 06

Posted 29 June 2015 - 07:30 PM

My assumption would be that would depend if you had A;  had a computer that could read two and B; had separate bank firing to make any significant difference and C' the custom tune to run it that way.

 

The difference would be the computer could trim fuel at cruise or WOT independently left to right bank.

 

Topically you run slightly rich on acceleration and lean on deceleration.



#4 _SLY HR_

_SLY HR_
  • Guests

Posted 29 June 2015 - 07:42 PM

I've noticed over the years that VN-VS V8 engines have one sensor and the sequentially injected VS3 (and VT) engines have two. So more than likely you need one in each bank for sequentially injected engines and only the one for batch fired systems?

 

Interesting point

 

 

My assumption would be that would depend if you had A;  had a computer that could read two and B; had separate bank firing to make any significant difference and C' the custom tune to run it that way.

 

The difference would be the computer could trim fuel at cruise or WOT independently left to right bank.

 

Topically you run slightly rich on acceleration and lean on deceleration.

 

Let's say, for the sake of simplicity, we are talking about a standalone wideband AFR meter (such as the LM-2)

I would not have thought there would be discernible difference between the two? 



#5 EunUCh

EunUCh

    Lotsa Posts!

  • Members
  • PipPipPipPipPipPip
  • 2,761 posts
  • Location:not this planet
  • Car:japos
  • Joined: 23-November 06

Posted 29 June 2015 - 07:52 PM

Both of the above , the early v6 had 1 O2 sens. where as the Ecotech had 2 and so did the 8 by the sound of it because they were sequential and the computer needs to be able to read both to trim both banks,on a straight six with divided system depending on how they were divided you could probably get away with 2 provided the computer can read them both,or is it carbed and just being used for tuning?



#6 _SLY HR_

_SLY HR_
  • Guests

Posted 29 June 2015 - 08:14 PM

Both of the above , the early v6 had 1 O2 sens. where as the Ecotech had 2 and so did the 8 by the sound of it because they were sequential and the computer needs to be able to read both to trim both banks,on a straight six with divided system depending on how they were divided you could probably get away with 2 provided the computer can read them both,or is it carbed and just being used for tuning?

 

Cheers.

If it was carb fed, and only being read for tuning purposes would there be enough of a difference between banks to warrant a second sensor?

As I imagine a dual exhaust red motor would have banks made up of cylinders 1-2-3 and 4-5-6?



#7 EunUCh

EunUCh

    Lotsa Posts!

  • Members
  • PipPipPipPipPipPip
  • 2,761 posts
  • Location:not this planet
  • Car:japos
  • Joined: 23-November 06

Posted 29 June 2015 - 08:32 PM

Should imagine that if it was carb. fed that they may be some distribution "issues" depending on induction setup , but still should be able to get it pretty close out of 1 sens. in one group of pipes ? ...the non. sequential set up probably just "averaged out" what was happening depending on how well the injectors were "matched" in flow? 

 

edit....example , don't know what plugs are supposed to look like on this "new fuel" , but after a "few" miles/years/slackness?

 

replaced the ones on one bank the other day !!!

Attached File  SfP.JPG   186.3K   0 downloads

 

 


Edited by EunUCh, 29 June 2015 - 08:42 PM.


#8 TerrA LX

TerrA LX

    Fulcrum Fixture

  • Members
  • PipPipPipPipPipPipPip
  • 14,241 posts
  • Location:Sid 'n' knee
  • Joined: 31-May 06

Posted 30 June 2015 - 12:00 AM

Cheers.

If it was carb fed, and only being read for tuning purposes would there be enough of a difference between banks to warrant a second sensor?

As I imagine a dual exhaust red motor would have banks made up of cylinders 1-2-3 and 4-5-6?

Your missing two important things...

7 and 8.

To relate it to a V8 red motor carby engine would be the difference between an open plenum inlet manifold and a duel plane manifold so to speak.
or little brother six, the difference between triples or a 4bbl Holley...

The best option would be to have an o2 sensor for every pot.



#9 76lxhatch

76lxhatch

    That was easy!

  • Members
  • PipPipPipPipPipPipPip
  • 7,142 posts
  • Location:Unzud
  • Car:SS
  • Joined: 04-August 08
Garage View Garage

Posted 30 June 2015 - 06:28 AM

In your case having two will allow you to pinpoint any problems that are causing differences, and/or decide on a fudge factor to make up for any small difference. You could achieve this by having two bungs and simply swapping the sensor from one to the other and comparing. Once you have that part sorted there would be no need for two separate sensors in this instance.

#10 yel327

yel327

    Oh My, Don't you post alot

  • Members
  • PipPipPipPipPipPipPip
  • 13,009 posts
  • Joined: 10-February 08

Posted 30 June 2015 - 08:33 AM

My assumption would be that would depend if you had A;  had a computer that could read two and B; had separate bank firing to make any significant difference and C' the custom tune to run it that way.

 

The difference would be the computer could trim fuel at cruise or WOT independently left to right bank.

 

Topically you run slightly rich on acceleration and lean on deceleration.

 


I thought that (at least) the early batch fired injection systems like VN-VS only used the O2 sensor (closed loop control) at idle? And that under power the engine ran in open loop (ie sensor ignored).

 

My Hilux has 4 x sensors on it. one either side of the cats on each bank. 



#11 TerrA LX

TerrA LX

    Fulcrum Fixture

  • Members
  • PipPipPipPipPipPipPip
  • 14,241 posts
  • Location:Sid 'n' knee
  • Joined: 31-May 06

Posted 30 June 2015 - 09:25 AM


I thought that (at least) the early batch fired injection systems like VN-VS only used the O2 sensor (closed loop control) at idle? And that under power the engine ran in open loop (ie sensor ignored).

Upto vs series 1?

All temperature, throttle position, road speed and air pressure dependent AFIK when the sensor can not be used base tables take over.



#12 yel327

yel327

    Oh My, Don't you post alot

  • Members
  • PipPipPipPipPipPipPip
  • 13,009 posts
  • Joined: 10-February 08

Posted 30 June 2015 - 09:51 AM

I think up to earlier VSIII (1998-ish) the engines are the same afaik. After that and up to the end of VS in 2000 the engines were sequential.



#13 76lxhatch

76lxhatch

    That was easy!

  • Members
  • PipPipPipPipPipPipPip
  • 7,142 posts
  • Location:Unzud
  • Car:SS
  • Joined: 04-August 08
Garage View Garage

Posted 30 June 2015 - 03:04 PM

I thought that (at least) the early batch fired injection systems like VN-VS only used the O2 sensor (closed loop control) at idle? And that under power the engine ran in open loop (ie sensor ignored).

Definitely not just idle, closed loop control under cruise (low load/throttle) conditions too. We still had fuel with lead content when the VNs came out here, these cars had no oxygen sensor and ran open loop all the time - the base tunes are actually quite accurate because they don't have the closed loop control to make up for it.

#14 EunUCh

EunUCh

    Lotsa Posts!

  • Members
  • PipPipPipPipPipPip
  • 2,761 posts
  • Location:not this planet
  • Car:japos
  • Joined: 23-November 06

Posted 30 June 2015 - 05:20 PM

dunno if this is of any help,but for those interested,hope it's readable enough.

Attached File  o2v8.JPG   262.96K   2 downloads



#15 _SLY HR_

_SLY HR_
  • Guests

Posted 25 August 2015 - 06:06 PM

In your case having two will allow you to pinpoint any problems that are causing differences, and/or decide on a fudge factor to make up for any small difference. You could achieve this by having two bungs and simply swapping the sensor from one to the other and comparing. Once you have that part sorted there would be no need for two separate sensors in this instance.

 

Hi all.
Just thought I would report back - I have had two bungs welded into each bank of pipes and will read one at a time as mentioned above.

Once its all up and running we shall see if there is much of a difference.

Regards


Edited by SLY HR, 25 August 2015 - 06:07 PM.


#16 ozyozyozy

ozyozyozy

    Forum Fixture

  • Members
  • PipPipPipPipPip
  • 944 posts
  • Location:perth
  • Joined: 13-February 08

Posted 25 August 2015 - 10:23 PM

Simple answer, better control of emissions having 2 sensors.
With sequential injection and 2 sensors they can monitor what is going on in each cylinder, this can be used for missfire detection.
Later ecu's are more powerful, more features.
Most new cars run 4 o2 sensors, on v8 and v6's once again for better emission control and monitoring cat convertor health




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users