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EFIE/O2 sensor correct voltage???
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originalmazdawg Offline
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Post: #1
EFIE/O2 sensor correct voltage???
For reference, here's a "piece" of the instructions pasted...

"Most computers will see 425 millivolts from the EFIE, plus the sensor's voltage as high all the time. In other words even when the sensor is putting out it's lowest voltage, when the EFIE adds 425 millivolts, the computer will think the sensor is reading high. The computer will think the sensor is damaged, because it reads high all the time, and will ignore it's data. If this occurs you may or may not get a check engine light alerting you to the "defective oxygen sensor", but for sure your gas mileage will get very bad. So you should never operate your EFIE this high. The exact voltage is .45 volts to the ECU. Above that voltage is "high" and below that voltage is "low". The ECU must see transitions from low to high several times per second or it will "know" that the sensor is bad and then just start merrily adding gas."

It says that the "exact" voltage required is .45 volts, not lower or higher. I have installed a dual EFIE per instructions. I am using a scan tool to watch the voltage from the O2 sensors. In order to keep the voltage at the "exact .45 volts", the adjustment is all the way down. I am getting a reading of .19v from the test ports in order to keep the signal in the .45v range. Am I doing something wrong? The voltages do not change with the unit turned off or on. I keep reading that a "good starting point" is around .2v or 200 millivolts. If I set it that high, the O2 sensor voltage goes up significantly past the .45v range.

The vehicle is an '08 F250 w/ a 5.4L gas engine. We have installed a Hydrogen Generator unit.
09-24-2008 12:09 PM
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colchiro Offline
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Post: #2
RE: EFIE/O2 sensor correct voltage???
Did you confirm you have a narrow band sensor before installing it?

With your voltmeter's red probe in the black jack and your black probe connected to ground, what do you get for a meter reading? A narrow band sensor would have a rapidly changing voltage between .1 and 1 VDC.

Where did you connect to your o2, under the hood or at the ecu?

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
09-24-2008 03:38 PM
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originalmazdawg Offline
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RE: EFIE/O2 sensor correct voltage???
colchiro Wrote:Did you confirm you have a narrow band sensor before installing it?

With your voltmeter's red probe in the black jack and your black probe connected to ground, what do you get for a meter reading? A narrow band sensor would have a rapidly changing voltage between .1 and 1 VDC.

Where did you connect to your o2, under the hood or at the ecu?

Yes, it is narrow, rapidly changing from .11v to 1.0v and averaging around the .45v-.50v range, according to my scan tool. I spliced into the wire before the connector to the pcm that is under the hood. The pcm on this model is mounted into the firewall, so that the connectors from the main harness literally just plug into the firewall. According to the wiring schematics for this truck, it's a four wire O2 sensor,... heater, heater-ground, signal, and signal-ground.
09-25-2008 05:07 AM
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colchiro Offline
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RE: EFIE/O2 sensor correct voltage???
You're over-reacting to that .45 volt thing. Ignore that, this one's easier to figure out (and much shorter)....

Keep your offset voltage below 400 mv and you'll be good. Wink

The offset is what the efie adds to the original signal, and is measured between the red and black connectors on the deluxe efie or the o2 sensor wire and ecu ... (the o2 wire you cut) on other efies.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
09-25-2008 03:41 PM
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PanamaRik Offline
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RE: EFIE/O2 sensor correct voltage???
re: The part of the quote you have in bold. That is the average or mean voltage the computer is aiming for when it sets the fuelling. The O2 sensor will send a range of signals from 0.1 to 1.0 v. depending on the amount of oxygen it senses in the exhaust. A low voltage means the sensor is reading a weak mix so the computer adds fuel, that makes the O2 sensor send a high voltage to the computer which reacts by reducing fuel.

If you set the voltage from the EFIE too high, in your example .425v, then the total voltage seen by the computer will always be above the .45v average. The computer sees that as a fault and goes into open loop for safety. That is the only meaning of exact .45v. The average value which gets crossed several times per second if the sensor is working properly.

When you add hydroxy the exhaust gas appears lean due to the improved combustion. This alone can trigger a fault code if the signal stays low. The EFIE adds enough voltage to the O2 sensor signal to bring it back into the correct operating range. Going too high with the added voltage will also trigger a fault code, as the sensor output plus EFIE voltage stays above the average level. It can also trigger a code if the max values go above the limit programmed into the ECM

So don't worry about trying to keep the reading at.45v, it'll make you dizzy watching the voltmeter Smile . Start at .2v added and increase a bit at a time until you find the point where either your engine starts to stumble or knock, then back off a bit.

If you have access to a scan tool that can record values, run without hydroxy for a while and record the max, min and average values generated by the O2 sensor. Then add hydroxy and record the new values. The difference in the average value is the amount of mv you need to add with the EFIE. You may be able to go a fraction higher, so long as the max value plus EFIE voltage does not exceed the programmed limit. Don't overdo it tho or the engine will be running weak.

PanamaRik

originalmazdawg Wrote:For reference, here's a "piece" of the instructions pasted...

"Most computers will see 425 millivolts from the EFIE, plus the sensor's voltage as high all the time. In other words even when the sensor is putting out it's lowest voltage, when the EFIE adds 425 millivolts, the computer will think the sensor is reading high. The computer will think the sensor is damaged, because it reads high all the time, and will ignore it's data. If this occurs you may or may not get a check engine light alerting you to the "defective oxygen sensor", but for sure your gas mileage will get very bad. So you should never operate your EFIE this high. The exact voltage is .45 volts to the ECU. Above that voltage is "high" and below that voltage is "low". The ECU must see transitions from low to high several times per second or it will "know" that the sensor is bad and then just start merrily adding gas."

It says that the "exact" voltage required is .45 volts, not lower or higher. I have installed a dual EFIE per instructions. I am using a scan tool to watch the voltage from the O2 sensors. In order to keep the voltage at the "exact .45 volts", the adjustment is all the way down. I am getting a reading of .19v from the test ports in order to keep the signal in the .45v range. Am I doing something wrong? The voltages do not change with the unit turned off or on. I keep reading that a "good starting point" is around .2v or 200 millivolts. If I set it that high, the O2 sensor voltage goes up significantly past the .45v range.

The vehicle is an '08 F250 w/ a 5.4L gas engine. We have installed a Hydrogen Generator unit.

Drop by my site at http://gassaver.panamacentric.com and say 'Hi' Rik
09-25-2008 06:45 PM
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originalmazdawg Offline
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Post: #6
RE: EFIE/O2 sensor correct voltage???
colchiro Wrote:You're over-reacting to that .45 volt thing. Ignore that, this one's easier to figure out (and much shorter)....

Keep your offset voltage below 400 mv and you'll be good. Wink

The offset is what the efie adds to the original signal, and is measured between the red and black connectors on the deluxe efie or the o2 sensor wire and ecu ... (the o2 wire you cut) on other efies.

I think the wording of that sentence is...uhm, in need of updating, maybe without the word "exact" in there then. That is what caused most of my confusion, it said exact, but I figured average.

I appreciate the replies, they really helped out. Now I know where to start, Thanks!
09-26-2008 05:23 AM
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dblcreek Offline
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RE: EFIE/O2 sensor correct voltage???
(09-26-2008 05:23 AM)originalmazdawg Wrote:  
colchiro Wrote:You're over-reacting to that .45 volt thing. Ignore that, this one's easier to figure out (and much shorter)....

Keep your offset voltage below 400 mv and you'll be good. Wink

The offset is what the efie adds to the original signal, and is measured between the red and black connectors on the deluxe efie or the o2 sensor wire and ecu ... (the o2 wire you cut) on other efies.

I think the wording of that sentence is...uhm, in need of updating, maybe without the word "exact" in there then. That is what caused most of my confusion, it said exact, but I figured average.

I appreciate the replies, they really helped out. Now I know where to start, Thanks!
for my situation
and if i am understanding this right .
i am going into efie with 1.25 volts from map sensor i should adjust to come out of the efie to cpu with approx .4 volts more.....is that correct? im a bit confusedBlush
10-13-2011 07:28 PM
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