slightly general FI quesiton

espguitarist33 · 09-23-2009, 11:23 AM

so I was just thinking....when your running forced induction on the old ecu (piggybacked though) and the old o2 sensor......wouldnt the added exhaust flow make the computer think the car is running rich?

and to stack it...if its a V type engine...if one of the upstream o2 sensors is reading both banks...wouldnt that make it seem even richer?

i want to go FI on my slivertop at some point so it is a good consideration but i have a v6 turbo'd eclipse that i was like ya know something..hm..

mr2tim · 10-05-2009, 02:12 PM

Mr guitar

In pondering your question I believe you should know that "our" Supercharged engines are equipped with 100cc injectors that are producing/flowing 66% more volume than the Normal Aspirated version of the same displacement engine.

I have often noticed strong unburned fuel vapors while under boost when in low RPM ranges when operating on the streets for decades.

I am not sure, nor can I prove it, but I speculate that the o2 sensor input may be limited by OEM computer mapping when the system is under boost and/or WOT conditions or perimeters.

I have no input whatsoever on the piggyback PNP systems, but I might suggest to you that the larger SC injectors and possibly the SC ECU be used in your future pressurized "Silvertop" adventures.

It should be remembered that extra unburnt fuel adds to the cooling of the piston and is not neccessarily a bad thing.

Supercharzed Toyz
A Toyota Race Team since 1989

espguitarist33 · 10-05-2009, 02:25 PM

makes sense...it made me worry in my eclipse if the computer thinks its running really rich..wont it lean it way out...possibly dangerously lean? idk maybe i worry too much

ToyotaTechGeek · 10-05-2009, 04:00 PM

i thought they are 365's?!?!?!

well, the SC 'dumps' fuel under boost. i believe it's more TPS-operated than 02 at that point.

Papo J · 10-06-2009, 08:01 AM

The O2 sensor doesn't measure air volume but the unburnt fuel in it so it doesn't matter how much air is flowing by it will always meassure the the same thing. The SC injectors are 365cc not 100cc and the ECU ignores the O2 sensor at anything past 1/2 throttle or so, it is only used by the ECU while cruising or during low load conditions.

At least that's how it works on our cars, some newer vehicles which use wide band O2 sensors are continually varying the fuel mixture based on O2 sensor input to the ECU, air temp, etc.

ToyotaTechGeek · 10-06-2009, 08:16 AM

also, i believe that the SC injector plugs are different from the NA

toyotaspeed90 · 10-06-2009, 03:28 PM

depends on the 4age vs 4agze you are talking about.... there are several different plugs.

the gze uses 365's... probably measuered at around 40psi of fuel.
the early bigport uses 212's, 250's in the smallports, and 270's in the 20v's (which are sidefeed).

sometimes you will hear someone getting test results back from their injectors and it's different than factory... that's because some testing facilities use a higher PSI.... an injector works for a specific amount of time that the spintle is open for and allows X amount of fuel through.... that amount of fuel is based upon how much pressure is behind the injectors.

In any event... if you are using a piggy back... then the sole purpose of the 'band aid' computer is to trick the stock ecu into thinking everything is working ok. Meaning, if the piggyback is tuned and expects a certain 02 reading, it will still send back a stoich (or % of what it's reading) measurement to the stock ecu. that's why it's called a piggy back, and why a friend of mine (and I picked up) calls them 'band aid' computers.

espguitarist33 · 10-07-2009, 05:30 PM

far from my question

i just wandered if it read percentage by the certain volume
or if it was percentage of the total exhaust it sees

thus why i wondered if both banks fed to one changes the reading

toyotaspeed90 · 10-12-2009, 06:18 PM

well, I did answer your question....

first of all... a piggy back will receive the 02 reading, not your ecu.... the piggy back will trick the ecu into thinking everything is normal... that's the purpose of a piggy back.

second of all.... the ecu reads a fuel vs air value... stoich is 14.7:1.... which is basically PPM of unburned fuel vs. air (which is the job of the o2 sensor).... whether there is 1cfm or 1,000 cfm moving through a space, the sensor will read the same ppm.

your system should read rich because you should be running rich with forced induction...

lean in n/a is good.... lean in FI is bad.....

lastly... if you're in a v6 and it's reading 10.0:1 at one V bank and a downstream is reading 16.0:1, then it should tell you there's a major problem with both banks, and they are somehow out of sync in terms of their AF values. The way that FI works is usually injectors are fired in a batch.... so, for instance in a 4age cylinders 1 and 3 then 2 and 4 fire at the same time..... this is based on firing order, so in a V6 it wouldn't be based on bank, because firing order is never 1, 2, 3, 4...... if it was designed that way it would be the shakiest engine ever....

espguitarist33 · 10-12-2009, 10:15 PM

wow i dont remember saying piggybacked

the ppm part is what i was looking for though

thanks

toyotaspeed90 · 10-13-2009, 12:02 PM

Quote:

Originally Posted by espguitarist33

so I was just thinking....when your running forced induction on the old ecu (piggybacked though) and the old o2 sensor......wouldnt the added exhaust flow make the computer think the car is running rich?

sorry, but I had to....

espguitarist33 · 10-13-2009, 12:14 PM

thank you thank you

i looked up i was like oh wow i typed that?

09-23-2009, 11:23 AM	#1 (permalink)
espguitarist33 Cage Fighter Join Date: Nov 2008 Location: west chester PA Posts: 415 Thanks: 4 Thanked 5 Times in 5 Posts iTrader Rating: (2/100% )	slightly general FI quesiton so I was just thinking....when your running forced induction on the old ecu (piggybacked though) and the old o2 sensor......wouldnt the added exhaust flow make the computer think the car is running rich? and to stack it...if its a V type engine...if one of the upstream o2 sensors is reading both banks...wouldnt that make it seem even richer? i want to go FI on my slivertop at some point so it is a good consideration but i have a v6 turbo'd eclipse that i was like ya know something..hm..

10-05-2009, 02:12 PM	#2 (permalink)
mr2tim SUPERcharZed ToyZ RacZer Join Date: Mar 2008 Location: South Florida Posts: 690 Thanks: 2 Thanked 41 Times in 38 Posts My Google Map iTrader Rating: (2/100% )	Sensor vs OEM mapping? Mr guitar In pondering your question I believe you should know that "our" Supercharged engines are equipped with 100cc injectors that are producing/flowing 66% more volume than the Normal Aspirated version of the same displacement engine. I have often noticed strong unburned fuel vapors while under boost when in low RPM ranges when operating on the streets for decades. I am not sure, nor can I prove it, but I speculate that the o2 sensor input may be limited by OEM computer mapping when the system is under boost and/or WOT conditions or perimeters. I have no input whatsoever on the piggyback PNP systems, but I might suggest to you that the larger SC injectors and possibly the SC ECU be used in your future pressurized "Silvertop" adventures. It should be remembered that extra unburnt fuel adds to the cooling of the piston and is not neccessarily a bad thing. Supercharzed Toyz A Toyota Race Team since 1989

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10-05-2009, 02:25 PM	#3 (permalink)
espguitarist33 Cage Fighter Join Date: Nov 2008 Location: west chester PA Posts: 415 Thanks: 4 Thanked 5 Times in 5 Posts iTrader Rating: (2/100% )	makes sense...it made me worry in my eclipse if the computer thinks its running really rich..wont it lean it way out...possibly dangerously lean? idk maybe i worry too much

10-05-2009, 04:00 PM	#4 (permalink)
ToyotaTechGeek Giapetto is NOT my dad! Join Date: Mar 2005 Location: ...boosting mid-corner Posts: 568 Thanks: 7 Thanked 13 Times in 13 Posts My Google Map iTrader Rating: (1/100% )	i thought they are 365's?!?!?! well, the SC 'dumps' fuel under boost. i believe it's more TPS-operated than 02 at that point.

10-06-2009, 08:01 AM	#5 (permalink)
Papo J 6SPD GTE Join Date: Sep 2006 Posts: 189 Thanks: 1 Thanked 19 Times in 18 Posts iTrader Rating: (0/0% )	The O2 sensor doesn't measure air volume but the unburnt fuel in it so it doesn't matter how much air is flowing by it will always meassure the the same thing. The SC injectors are 365cc not 100cc and the ECU ignores the O2 sensor at anything past 1/2 throttle or so, it is only used by the ECU while cruising or during low load conditions. At least that's how it works on our cars, some newer vehicles which use wide band O2 sensors are continually varying the fuel mixture based on O2 sensor input to the ECU, air temp, etc.

10-06-2009, 08:16 AM	#6 (permalink)
ToyotaTechGeek Giapetto is NOT my dad! Join Date: Mar 2005 Location: ...boosting mid-corner Posts: 568 Thanks: 7 Thanked 13 Times in 13 Posts My Google Map iTrader Rating: (1/100% )	also, i believe that the SC injector plugs are different from the NA

10-06-2009, 03:28 PM	#7 (permalink)
toyotaspeed90 No Skills Join Date: Jun 2006 Location: Bellingham, WA Posts: 422 Thanks: 0 Thanked 32 Times in 32 Posts My Google Map iTrader Rating: (0/0% )	depends on the 4age vs 4agze you are talking about.... there are several different plugs. the gze uses 365's... probably measuered at around 40psi of fuel. the early bigport uses 212's, 250's in the smallports, and 270's in the 20v's (which are sidefeed). sometimes you will hear someone getting test results back from their injectors and it's different than factory... that's because some testing facilities use a higher PSI.... an injector works for a specific amount of time that the spintle is open for and allows X amount of fuel through.... that amount of fuel is based upon how much pressure is behind the injectors. In any event... if you are using a piggy back... then the sole purpose of the 'band aid' computer is to trick the stock ecu into thinking everything is working ok. Meaning, if the piggyback is tuned and expects a certain 02 reading, it will still send back a stoich (or % of what it's reading) measurement to the stock ecu. that's why it's called a piggy back, and why a friend of mine (and I picked up) calls them 'band aid' computers.

10-07-2009, 05:30 PM	#8 (permalink)
espguitarist33 Cage Fighter Join Date: Nov 2008 Location: west chester PA Posts: 415 Thanks: 4 Thanked 5 Times in 5 Posts iTrader Rating: (2/100% )	far from my question i just wandered if it read percentage by the certain volume or if it was percentage of the total exhaust it sees thus why i wondered if both banks fed to one changes the reading

10-12-2009, 06:18 PM	#9 (permalink)
toyotaspeed90 No Skills Join Date: Jun 2006 Location: Bellingham, WA Posts: 422 Thanks: 0 Thanked 32 Times in 32 Posts My Google Map iTrader Rating: (0/0% )	well, I did answer your question.... first of all... a piggy back will receive the 02 reading, not your ecu.... the piggy back will trick the ecu into thinking everything is normal... that's the purpose of a piggy back. second of all.... the ecu reads a fuel vs air value... stoich is 14.7:1.... which is basically PPM of unburned fuel vs. air (which is the job of the o2 sensor).... whether there is 1cfm or 1,000 cfm moving through a space, the sensor will read the same ppm. your system should read rich because you should be running rich with forced induction... lean in n/a is good.... lean in FI is bad..... lastly... if you're in a v6 and it's reading 10.0:1 at one V bank and a downstream is reading 16.0:1, then it should tell you there's a major problem with both banks, and they are somehow out of sync in terms of their AF values. The way that FI works is usually injectors are fired in a batch.... so, for instance in a 4age cylinders 1 and 3 then 2 and 4 fire at the same time..... this is based on firing order, so in a V6 it wouldn't be based on bank, because firing order is never 1, 2, 3, 4...... if it was designed that way it would be the shakiest engine ever....

10-12-2009, 10:15 PM	#10 (permalink)
espguitarist33 Cage Fighter Join Date: Nov 2008 Location: west chester PA Posts: 415 Thanks: 4 Thanked 5 Times in 5 Posts iTrader Rating: (2/100% )	wow i dont remember saying piggybacked the ppm part is what i was looking for though thanks

10-13-2009, 12:14 PM	#12 (permalink)
espguitarist33 Cage Fighter Join Date: Nov 2008 Location: west chester PA Posts: 415 Thanks: 4 Thanked 5 Times in 5 Posts iTrader Rating: (2/100% )	thank you thank you i looked up i was like oh wow i typed that?