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Fluctuating voltage...is this OK?!
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syncromon Offline
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Post: #1
Fluctuating voltage...is this OK?!
So, I hooked up my replacement EFIE, green to a NEW Bosch O2 Sensor, white to Computer, red to power wire (o2 heater wire, measures 13.3V when running), and black to body.
With the engine off, (key in ON position), I set the range to .300V, and the voltage to .200V, everything stays steady.
I have a voltmeter hooked up to the white/green wires so I can monitor the setting while driving.
When I start the engine, the voltage will climb to a point in the first few seconds (around .060V) then drop back down for a bit (.020V or less), and a few minutes later will start climbing again. When driving around 60mph, the EFIE output is around .100V, and will fluctuate a bit if I accelerate/decelerate. When in stop/go city driving, the voltage climbs when I stop (to around .170V) and drops while accelerating to somewhere around .100V -.130V.
Has anybody else monitored their EFIE readings while driving? I hear it is supposed to remain constant. I tried hooking the red wire to another power source (switched HHO power wire from battery) and it still fluctuates.
When I measure the O2 sensor signal (green wire and ground) I get the fluctuating readings from .0 to .7V as expected.
Just curious if anyone else reads the EFIE voltage while driving, and what they experience.

THANKS! SyncromonHmm
04-25-2008 10:11 AM
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colchiro Offline
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Post: #2
RE: Fluctuating voltage...is this OK?!
The voltage between the EFIE (red and black) terminals should be stable.

Either terminal to body ground will be rapidly changing since that's the o2 sensor output.

Rick

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(This post was last modified: 04-25-2008 02:44 PM by colchiro.)
04-25-2008 02:44 PM
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mike Offline
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RE: Fluctuating voltage...is this OK?!
There is something quite wrong. The EFIE voltage should be steady as colchiro points out.

There is something unknown here. Like there are some voltages being put on that circuit that aren't from the EFIE. Or maybe the green or white wires from the EFIE are connected to something else besides the sensor and computer.

You say you've got a replacement EFIE. I haven't replaced one for ages, so you must've gotten yours from someone else. Who did you get it from?

Are you certain that your sensor is not an AFR sensor, or a 5-wire wide band sensor (you would probably need a manual to verify this)? Did you install the sensor as per my diagram in the EFIE Installation Instructions? Note, it doesn't matter if you got the EFIE from someone else, just check the wiring diagram in the instructions and verify you hooked yours up the same way.

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04-25-2008 05:41 PM
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syncromon Offline
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Post: #4
RE: Fluctuating voltage...is this OK?!
Uhhm, I bought it from you, you claimed it was the first one that you had seen go bad (you said the wiring harness was bad), and this was about 2 weeks ago?!



mike Wrote:There is something quite wrong. The EFIE voltage should be steady as colchiro points out.

There is something unknown here. Like there are some voltages being put on that circuit that aren't from the EFIE. Or maybe the green or white wires from the EFIE are connected to something else besides the sensor and computer.

You say you've got a replacement EFIE. I haven't replaced one for ages, so you must've gotten yours from someone else. Who did you get it from?

Are you certain that your sensor is not an AFR sensor, or a 5-wire wide band sensor (you would probably need a manual to verify this)? Did you install the sensor as per my diagram in the EFIE Installation Instructions? Note, it doesn't matter if you got the EFIE from someone else, just check the wiring diagram in the instructions and verify you hooked yours up the same way.
04-26-2008 04:05 PM
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mike Offline
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RE: Fluctuating voltage...is this OK?!
Oh, yes, I remember it well. It was the wiring harness. The EFIE itself turned out to be fine. I'm pretty sure I sent you back the same one with a new harness. But now I get what you mean by "replacement EFIE".

Ok. In answer to your question, I have watched efie readings while driving around, and the efie does remain steady. Something is either wrong with your setup, or you have something other than a narrow band oxygen sensor (sounds unlikely since you just replaced it and would know), or the EFIE itself is faulty is some unusual way.

What you describe indicates a possible connection between the white or green wires and ground or power. The EFIE voltage is a floating voltage that rides up and down on top of the sensor's voltage. It almost sounds like yours isn't floating, which means it has an unknown connection to the vehicles electrical system. This could happen through a mis-wiring, and it could happen if there was an internal short in the EFIE itself.

You just have the single circuit board, right? Maybe I missed the boat when you sent that thing back in. I know I tested it, but may not have caused the condition that makes it do what you are reporting.
I certainly didn't put in my car to test it, but tested it on the bench.

If you've double checked your wiring, I think I'll cross ship you a new EFIE. I guess it's possible I sent you back the same bad EFIE, thinking it was fine. That would be most embarrassing.

PM or email me with your details again. I need your name and address and such. We'll get this thing handled.

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04-26-2008 09:23 PM
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