[Tuning] O2 sensor in each header primary. When?
Thread Starter
Le Mans Master
Joined: Jul 2001
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From: Santa Maria, CA
[Tuning] O2 sensor in each header primary. When?
I saw a pic of an engine on a engine dyno and instead of the EGT sensors on each primary, there were O2 sensors(neat!).
EGT sensor info is cool an all that, and I'd be jazzed if I had them with racepak, but A/F ratios really do it for me.
Wouldn't it be killer to have WBO2 info off each header primary?
So I dunno what kinda ECU was on that engine dyno, but it got me thinking/dreaming.
I wonder what it would take to pull it off on a car? Think of the possibilities.
Thoughts? :cool:
[Modified by 89 Paul in Cal, 10:36 PM 11/19/2003]
EGT sensor info is cool an all that, and I'd be jazzed if I had them with racepak, but A/F ratios really do it for me.
Wouldn't it be killer to have WBO2 info off each header primary?
So I dunno what kinda ECU was on that engine dyno, but it got me thinking/dreaming.
I wonder what it would take to pull it off on a car? Think of the possibilities.
Thoughts? :cool:
[Modified by 89 Paul in Cal, 10:36 PM 11/19/2003]
Former Vendor
Joined: Jun 2001
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From: St Marys PA
Re: [Tuning] O2 sensor in each header primary. When? (89 Paul in Cal)
Paul,
An O2 is not at all necessary with a stock ECm which is a batch fire fuel system. It does to one side or all cylinders what it doesn to all of them. So in theory you would not gain anything other than maybe going crossed-eyed trying to watch 8 digital volts meters all telling you basically the same thing.
Now some of the aftermarket ECM allow full control of each cylinders Air/Fuel ratio. With this you can trim and fine tune each one. But for the average lay-man its WAY WAY overkill and you better have a whole lot of time on your hands. Hell 90% of the people here have a hard enough time or should I say enough time to dial a car that changes all them at once , me included! :jester
So at the end of the day, it really probably more show than go oriented. If you want to get a cross sample of the one entire bank of cylinders, just move the 02 to the collector, where the 4 primaries converge. Just make sure its getting enough heat, otherwise get a heated unit.
Also reading plugs is a great way to tell what is happing in individual cylinders. :cheers: :thumbs:
An O2 is not at all necessary with a stock ECm which is a batch fire fuel system. It does to one side or all cylinders what it doesn to all of them. So in theory you would not gain anything other than maybe going crossed-eyed trying to watch 8 digital volts meters all telling you basically the same thing.
Now some of the aftermarket ECM allow full control of each cylinders Air/Fuel ratio. With this you can trim and fine tune each one. But for the average lay-man its WAY WAY overkill and you better have a whole lot of time on your hands. Hell 90% of the people here have a hard enough time or should I say enough time to dial a car that changes all them at once , me included! :jester
So at the end of the day, it really probably more show than go oriented. If you want to get a cross sample of the one entire bank of cylinders, just move the 02 to the collector, where the 4 primaries converge. Just make sure its getting enough heat, otherwise get a heated unit.
Also reading plugs is a great way to tell what is happing in individual cylinders. :cheers: :thumbs:
Team Owner
Joined: Mar 2000
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From: Boston, MA
Re: [Tuning] O2 sensor in each header primary. When? (ski_dwn_it)
An O2 is not at all necessary with a stock ECm which is a batch fire fuel system. It does to one side or all cylinders what it doesn to all of them. So in theory you would not gain anything other than maybe going crossed-eyed trying to watch 8 digital volts meters all telling you basically the same thing.
Being a batch fire system doesn't mean it has no benefits.
Drifting
Joined: Aug 2000
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From: West Islip New York
Re: [Tuning] O2 sensor in each header primary. When? (scorp508)
Being a batch fire system doesn't mean it has no benefits.
Can you control each injector with the stock batch system, or do they all have the same on time ?
Team Owner
Joined: Mar 2000
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From: Boston, MA
Re: [Tuning] O2 sensor in each header primary. When? (1MoorTym)
OK, stupid question here.
Can you control each injector with the stock batch system, or do they all have the same on time ?
Race Director
Joined: Sep 2000
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From: The Top of Utah
Re: [Tuning] O2 sensor in each header primary. When? (1MoorTym)
OK, stupid question here.
Can you control each injector with the stock batch system, or do they all have the same on time ?
Can you control each injector with the stock batch system, or do they all have the same on time ?
RACE ON!!!
Instructor
Joined: Oct 2000
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From: des plaines, il
Re: [Tuning] O2 sensor in each header primary. When? (89 Paul in Cal)
The 94+ engines have individual injector ECM trim for each cylinder, used to balance out uneven air flow in the LT1 intake manifold.
Individual O2 sensors would be fun but not really necessary. A single WB in one header (at a time) with a fast datalogger
is able to show differences between cylinder firings - at least at lower RPMs. It wouldn't tell you which cyl was lean/rich
but it would let you balance out the trims by playing around with the offset times.
Starting with balanced and flow matched injectors would be necessary however or you would be tweaking forever.
Individual O2 sensors would be fun but not really necessary. A single WB in one header (at a time) with a fast datalogger
is able to show differences between cylinder firings - at least at lower RPMs. It wouldn't tell you which cyl was lean/rich
but it would let you balance out the trims by playing around with the offset times.
Starting with balanced and flow matched injectors would be necessary however or you would be tweaking forever.
Drifting
Joined: Aug 2000
Posts: 1,521
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From: West Islip New York
Re: [Tuning] O2 sensor in each header primary. When? (CFI-EFI)
OK, stupid question here.
Can you control each injector with the stock batch system, or do they all have the same on time ?Possibly. Consider the word, "BATCH". Good luck, and...
RACE ON!!!
Can you control each injector with the stock batch system, or do they all have the same on time ?Possibly. Consider the word, "BATCH". Good luck, and...
RACE ON!!!
No biggie :D
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Race Director
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From: The Top of Utah
Re: [Tuning] O2 sensor in each header primary. When? (1MoorTym)
The way I understood Scorp, was that once you know the A/F ratio in each cylinder, you could adjust the mixture to make sure that the leanest cylinder isn't excessively lean. The point being, it's better to have 7 cylnders "fat", then have 1 cylinder lean, and blow your engine. Right, no biggie, but it helps if we all understand one another. Good luck, and...
RACE ON!!!
RACE ON!!!
Drifting
Joined: Aug 2000
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From: West Islip New York
Re: [Tuning] O2 sensor in each header primary. When? (CFI-EFI)
I just re-read it. You're right that is what Scorp means.
But since it is a batch system, how the heck would that ever work outside of WOT? Wouldn't the rest of the fat cylinders cause the system to pull fuel down to 14.7:1 while under 02 control anyway? I mean if you're using a single 02 to control the bank they are going to average out. You'd still be lean in that cylinder under less than WOT situations.
WOT would different because the 02 is not used right? So you could probably tune as Scorp suggested for that condition.
Right ?
But since it is a batch system, how the heck would that ever work outside of WOT? Wouldn't the rest of the fat cylinders cause the system to pull fuel down to 14.7:1 while under 02 control anyway? I mean if you're using a single 02 to control the bank they are going to average out. You'd still be lean in that cylinder under less than WOT situations.
WOT would different because the 02 is not used right? So you could probably tune as Scorp suggested for that condition.
Right ?
Race Director
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From: The Top of Utah
Re: [Tuning] O2 sensor in each header primary. When? (1MoorTym)
IWOT would different because the 02 is not used right? So you could probably tune as Scorp suggested for that condition.
Right ?
Right ?
The lean condition is the most dangerous at WOT. High pressures and temps are what cause engine distroying detonation and knock. This isn't a problem cruising down the highway. My older engine has only one O2. It doesn't even "see" the exhaust from the right bank of cylinders.
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Instructor
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From: Holbrook NY
Re: [Tuning] O2 sensor in each header primary. When? (CFI-EFI)
While WOT is the worse possible condition for even a slight lean tendency to suggest itself, it also is not possible for the stock O2 system to sample. The O2 sensor must be "settled in" before a reliable measurement can be made. There is no time for this at WOT, so we must trust our Performance Enrichment tables.
Furthermore at WOT the desired mixture is not within the range of factory sensors. A 13 to 1 mix is not at all rich for WOT, and will allow for performance boosting spark advance.over a 14:1 mix. I favor about 12:1 for my '85, as cylinder temperatures are reduced.
At the track you will see mixture ratios even richer than these. I do not believe that a street car would ever require a richer mix than 11:1 at WOT. For cruising, 14.7:1 might be OK, and the new direct port injection systems can run better than a 15:1 mix.
My point is that the oxygen sensor is not always a useful tool. Even the best wide range sensors have limitations. Multiple sensors could be useful to fine tune individual injectors in a direct port injection system, where very high mileage was the desired result.
George
Furthermore at WOT the desired mixture is not within the range of factory sensors. A 13 to 1 mix is not at all rich for WOT, and will allow for performance boosting spark advance.over a 14:1 mix. I favor about 12:1 for my '85, as cylinder temperatures are reduced.
At the track you will see mixture ratios even richer than these. I do not believe that a street car would ever require a richer mix than 11:1 at WOT. For cruising, 14.7:1 might be OK, and the new direct port injection systems can run better than a 15:1 mix.
My point is that the oxygen sensor is not always a useful tool. Even the best wide range sensors have limitations. Multiple sensors could be useful to fine tune individual injectors in a direct port injection system, where very high mileage was the desired result.
George
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From: Boston, MA
I mean if you're using a single 02 to control the bank they are going to average out. You'd still be lean in that cylinder under less than WOT situations.
WOT would different because the 02 is not used right? So you could probably tune as Scorp suggested for that condition.
WOT would different because the 02 is not used right? So you could probably tune as Scorp suggested for that condition.
Once you got WOT the O2 sensor is ignored and the ECM goes off of its Power Enrichment (WOT) tables to pre-programmed values. This is when that "tuning for the leanest cylinder" I mentioned comes into play and is useful in a batch system.
