EFIE ?

[jksav7]

Mike,

I got one of your EFIES, and I just installed it in my '94 Toyota pickup. It has one O2 sensor. I've had an air/fuel ratio gauge (the kind with the LEDs) on the pickup, so I know the 02 sensor is oscillating properly.

I hooked up the EFIE, double checking everything as I went. I know I hit the right wires, and I did cut the signal wire like the instructions say to do. I have a digital and analog voltmeter, but the analog meter is much more useful to find the oscillations. Anyway, I get small oscillations that max out at about 500 millivolts when I plug the positive test lead into the black (O2) port. The negative lead to ground, of course. The weird thing is that the oscillations bottom at below zero (negative) volts. I don't understand that.

When I plug the positive test lead into the computer side I get full range oscillations that I would expect. When I plug both leads into both ports, I get almost no reading at all. I can turn the adjusting up and down the scale, but the very minimal reading I get doesn't change.

So, the only thing that makes any sense to me is when I just plug the positive lead into the ECU port. I then could see the changes in oscillations as I turned the adjusting screw up or down. I simply took a guess that the computer will try to hit .5 volts, therefore I set the oscillations read from the ECU port to center around 700-750 millivolts.

Any ideas?

[mike]

I didn't understand the last paragraph.

But, let's check that the EFIE is functioning. Disconnect if from either (or both) the sensor or the ECU. This will take it out of the circuit. Now give it power and see if you get voltage between the red/black test ports. Make sure you can adjust that voltage with the set screw. If so, the EFIE is working properly, and there is something mis-wired when you installed it. I would look for shorts.

There is something definitely weird when you get negative readings on the signal wire. See if you can debug that before putting the EFIE back in.

Please let me know the results.

[jksav7]

I simply meant that when I plug the positive lead into the ECU port and the negative lead to ground I get normal oscillation readings from the voltmeter. This is what I would expect, whereas when I plug into the O2 side or have both leads plugged into both the ECU and O2 ports at the same time (to get the voltage offset) I get weird readings that shouldn't be.

In other words, the only way at this point that I can set up the EFIE is by taking the reading from the ECU port (assuming that the O2 sensor is reading 500 millivolts) and adjusting voltage to around 700-750 millivolts to hopefully hit that 200-250 offset voltage. Of course, this isn't totally accurate, and I will have to troubleshoot this per your directions. It might be a few days, but I'll get back to you.

mike Wrote:I didn't understand the last paragraph.

[mike]

Yes, there is something definitely wrong. We need to find out what it is, and get it corrected. I don't think you'll have any luck with that project until we do.

[jksav7]

Mike,

I disconnected the ECU side wiring in order to open the circuit. I then did the voltage test between the red and black ports. There was only .5 millivolt, and it didn't adjust with the dial going up and down.

Is there anything I could have done wrong in my set-up that would have caused this?

Funny thing is the air-fuel ratio gauge I have shows a lean condition when I turn the EFIE on. This tells me the EFIE is indeed sending a voltage to the ECU.

[mike]

I doubt you have a meter that can read .5 millivolts. That would be .0005 volts. I think you meant .5 volts, yes?

Ok, so the ECU side is in open air (that's the white EFIE wire), correct? And you don't get any change when you turn the adjustment? It's possible that earlier you turned it too far, past it's highest point, and now you have to turn it more times in the opposite direction to get it back to where it is changing it's resistance again. If you turn it 5 turns past the end, then you'll need to turn it 5 turns backwards before you'll start lowering the resistance again.

Did you ever change the range adjustment pot (It's inside the box, on the circuit board). If not, please keep it that way.

[jksav7]

I'll double check later, but I'm pretty sure it read .5 millivolts. Yes, the ECU side is in open air. It's entirely possible that I turned the dial too far, because I wasn't getting a reading. I turned it back and forth multiple times. If it's showing no voltage, then I would need to turn it clockwise to get it to increase offset, right?

I did not change the range adjustment pot.

Also, I think I read once that it's possible to screw the adjuster right out of it's socket?

mike Wrote:I doubt you have a meter that can read .5 millivolts. That would be .0005 volts. I think you meant .5 volts, yes?

Ok, so the ECU side is in open air (that's the white EFIE wire), correct? And you don't get any change when you turn the adjustment? It's possible that earlier you turned it too far, past it's highest point, and now you have to turn it more times in the opposite direction to get it back to where it is changing it's resistance again. If you turn it 5 turns past the end, then you'll need to turn it 5 turns backwards before you'll start lowering the resistance again.

Did you ever change the range adjustment pot (It's inside the box, on the circuit board). If not, please keep it that way.

[mike]

I believe you'll find that it shows .5 Volts. I think the lowest I've seen an EFIE go is about .017 volts or so (17 millivolts). They just don't go any lower than that.

So with that in mind, if it's at .5 volts then you want to go counter clockwise to lower it. and if it's at .017 volts then you want to go clockwise to raise it.

I think I've turned these things about 30 times past their end point and had them still work fine. Just use the info above to determine which way it needs to go, and you should be fine.

[jksav7]

Mike,

I had some time this afternoon, so I played around with it a little more. My digital multimeter does indeed read .5 millivolts when I have the leads plugged into the red and black ports. My analog meter basically shows no voltage when I do the same.

When I have the positive lead plugged into the red port and the black lead to ground I can see where the voltage adjustment (up or down) does have an effect. For example, I start with the EFIE off, and I can see the oscillations ranging from 0-850 millivolts. Then I'll turn the EFIE on and turn up the voltage, and the oscillation move up the scale while at the same time almost ceasing to oscillate. At some point the needle (analog meter) will just stop oscillating. I don't know if this is normal or not.

I've rechecked my wiring. Everything appears to be fine. It seems the EFIE is working, but I can't get a voltage read-out when I have the probes stuck into those red and black ports.

[mike]

Wow. That's a brain teaser. I wonder if there's a bad connection at the wiring harness. The white wire from the cable connects to the ECU and the green wire from the cable connects to the sensor. These wires connect directly to the red and black test ports respectively. If there is a voltage offset being added, and from your report it appears that there is, then it would have to show up across those ports.

Measure the voltage between the white and green wires. If the EFIE is adding voltage, you gotta see voltage there.

Note, you can send the unit back at any time, and I will take care of it for you. If you do this, please print out your last post, so I know where to start looking.