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Looking for some expert advice here.

 

Couple of us have bought the AEM UEGO which has a 0-5V output that we want to connect to the TEC2. For the AEM, 0V=10:1 and 5V=20:1, however, the TEC is expecting 0V=20:1 and 5V=10:1. Is there some sort of 5V inverter we can use? Any other solution? The AEM output cannot be changed.

 

TIA

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I have no experience with the AEM WBo2 but I know that the LC-1 output can be programmed to be whatever I want. 0-5V or 0-1V with the fuel ratio corresponding to whatever voltage I want.

 

I would guess the AEM can do the same thing. Their website says "User-programmable 0-5v analog output included for use with data loggers and virtually any engine management system". If I had the manual I could tell you more.

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What would be the point of using an expensive wide band in this case? A normal o2 sensor would be enough but, 0-1 V. sensors are no good for tuning purposes.

 

A normal O2 fluctuates too much, it is best used for tuning for or near stoich for low load and idle conditions (using the crossover point). A normal O2 sensor says whether a condition is rich or lean, not how rich or how lean.

 

A WBO2 has a linear response that actually corresponds to an AFR. Switching it to 0-1v instead of 0-5v will lose some resolution, but it will still be a linear response.

 

I don't know if you can do it with resistors though, there was a thread on doing something similar for using a cheap 1-wire AFR gauge with a WBO2.

 

Mario

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For the AEM, 0V=10:1 and 5V=20:1, however, the TEC is expecting 0V=20:1 and 5V=10:1. Is there some sort of 5V inverter we can use? Any other solution? The AEM output cannot be changed.
I'm not familiar with either of thse units, but taking what you wrote above at face value, for what you describe you would need to change the slope of the curve: from what you wrote above, for the AEM increasing voltage means leaner, and for the TEC, increasing voltage means richer. Resistors can only be used to scale the voltage while keeping the slope the same. It could be done with an Op Amp, but it's been too many years since my analog EE classes for me to create the schematic, and you'd still have to build it yourself.

 

Are you sure you don't have some options to change the input or output characteristics of the TEC and/or AEM?

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  • 4 weeks later...

I had no luck with support to go from the expensive $300 WBO2 sensor on the TEC2, I can empathize completely with people wanting to convert to a $30 WBO2 sensor and run it on their TEC. I would say to send an e-mail to JeffP, he's made up all sorts of DC-DC power converters for driving things in his car, I'm sure a voltage inverter shouldn't be all that hard for him. I'm forgetting the component that does it, but there is one I seem to recall that simply biases input voltages in reverse. For a +1V input it gives a -1 V output. Using that differential you start the conversion. It's been along time since looking at those circuits. It's stuff i want to forget, mechanical is more my bag! LOL

I'll watch this for the possibility of salvaging the TEC we yoinked out of our Bonneville car (and changed to the ECU882 Unit) for use in something else.

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According to the TEC3 manual the display readout on the TEC software is giving output at a multiple of 5. This means that the actual sensor reading is between 0V-1V. The software inturn boosts that signal reading to make adjustments easier showing an output of 0V-5V. It also says that a 0V is lean and 1V is rich. Maybe this was redesigned from the TEC2, but I couldn't imagine it being that much different given that they use the same tuning software. I would be worried that you're pushing to hot a signal back to the ECU and blowing something. If it's expecting an input of 0V-1V and getting something near 3v-5v then it could be screwing up the ECU. Just food for thought.

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I talked to jeff last night and touched on this, "Common Emitter Transistor" was the device. he says (greek to me) connecting one to the input, and the other to the common emitter output, with another to power and it should invert the voltage.

 

I probably have that all wrong, but it makes sense from what I was thinking.

 

You have power to one lead, a common output, and your signal to the third lead. The function of the device is to invert the signal, so +1 in could be configured with a "power supply in" (simple voltage regulating chip from +12VDC) of 5VDC, you would get that full 5VDC out the common emitter. By the time you get to 5VDC in on the signal end, you are down to 1VDC out the common output.

 

This has been 20+ years since going through that class, but this should not be hard to configure at all. Two chips and some wire, and you could literally shrink-wrap the whole schebang with the wires coming out and be done with it.

 

And not to be abrasive here, but the TEC3 is NOT the TEC2. They are WORLDS apart, developmentally. The TEC2 we used in the Bonneville car used a $300 UGEO sensor, and if we used anything else but the one supplied by Electramotive or their "value added dealer", it ran like crap, if at all. I totally understand why these guys want a work-around for the current generation of sensors.

 

But the TEC3 is not a TEC2. Just like the TEC1 is in a world of it's own...

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The TEC 2 will work quite well with a number of different WBO2 controllers. I have had good results in 8 TEC 2 installations with the Innovate LM-1 and the FJO systems. You just have to know how to interface them, get the calibration correct and matching in both the wideband and TEC, then use the setup to properly tune your engine.

 

Some widebands will not work with the TEC 2 because they have no provision to output a reverse curve from the low volts=lean to high volts=rich that the TEC expects. The AEM unit is one of these. It may be possible to change this in the calibration software. If this doesn't work we will build an op-amp circuit to invert the signal.

 

We had Scottie's and Zgad's LM-1s working well interfaced to the TEC, but they had opted to change to a different system because of The LM-1's propensity to "get stupid" on occasion. This has been proven to be a LM-1 problem rather than one with the TEC.

 

That 240ZTurbo, Scottie, and Z-Gad have had the results that have been shown so far is a testimonial to what the "archaic" TEC 2 is capable of when installed and tuned properly.

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  • 2 weeks later...

Just an Aside...

I had picked up one of our "Electromotive" O2 sensors. It was an NTK, but the part number had been "knurled" so as to make the number illegible.

 

Well, there was one in our box that was not so illegible. Now I had always assumed (insert your appropriate comment here about assuming things) that this was the expensive NTK unit, since the "value Added" dealer was selling them as such.

 

The P/N on the body I found was NTK 56027916...

 

Suprise, Suprise, Suprise! It corssreferenced for a DODGE TRUCK, and is available from several sources with an upper end price range around $102.43.

 

I am thinking the "Value Added" dude was crimping his own connections on Dodge sensors to cut costs... my paranoia aside, this may be another alternative for standard sensors for the TEC2 that should be identical to the ones supplied by the "Value Added Dealers".

 

For what it's worth.... And oh yeah, "Bump"! LOL

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TonyD,

 

You need to get some competent (or honest) support for the TEC2. It can use almost any universal replacement type narrowband O2 sensor. And,with VE tables properly done, it hardly needs to even have O2 feedback enabled at all! The narrowband sensor is unreliable or even useless in resolving any AFR outside the 14 to 15.5 range, making closed loop operation only feasible for idle and low-load operation. This will be true for any fuel management you use.

 

If you're serious about tuning, get a wideband interfaced to the TEC.

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So your saying my paranoia was justified?

Halleluija!

LOL

 

We got another system into the car now, but that TEC is just laying around. Maybe I will "bite the bullet" and install it in my street car. It really gave great service (17 World Land Speed Records for N/A 3 Liter Classes), but the Damper we installed was setup for the new system, and when we started having high-rpm sensor issues (8500+ rpm) we just gave up. We didn't have much luck with other sensors, but knowing this now it may help with the unit in the future.

 

We never actually ran in closed loop. Due to cam overlap, it was on blend till almost 50% throttle. We didn't use the unit at partial throttle, this was full on racing at Land Speed Events. I was "told" it was a WBO2.... hence my misunderstanding of the question above!

 

In the case of the TEC2 taking a 1V switched input, I'd go with the switched output from a WBO2 controller. But if there is a WBO2 interface already available.... hmmmmm....

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