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Old 02-01-2008, 03:01 PM   #1
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Default Need AEM UEGO with Greddy harness help ASAP

I'm trying to install an AEM UEGO using the greddy AF harness. The harness instruction tells me to hook the white wire to the analog + and the Grey wire to Analog - ....However, on the AEM controller directions, it does not distinguish betwen a positive or negative, just analog out. Orange 0-5 volt and white 0-1 volt. Which wires form the AEM do I hook my harness into?? Any help would be greatly appretiated, I'm trying to finish this today.
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Old 02-01-2008, 03:19 PM   #2
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Connect the orange 0-5v output wire of the AEM to the white wire of the EMU A/F harness, and connect the gray wire of the EMU A/F harness to Brown signal ground of the AEM. If this does not work, you may need to ground the grey wire.

Also be aware that the scaling of this controller's analog output is both non-linear and different from the more common gauge type. It is 8.4:1 at 0v and 19.5:1 at 5, with stoich at 4v.
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Old 02-01-2008, 03:27 PM   #3
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Connect the orange 0-5v output wire of the AEM to the white wire of the EMU A/F harness, and connect the gray wire of the EMU A/F harness to Brown signal ground of the AEM. If this does not work, you may need to ground the grey wire.

Also be aware that the scaling of this controller's analog output is both non-linear and different from the more common gauge type. It is 8.4:1 at 0v and 19.5:1 at 5, with stoich at 4v.
You day man!! thanks, That's what i thought but I didn't want to get it all togther and be wrong
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Old 02-01-2008, 07:34 PM   #4
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Thanks for the earlier help. I have one more question on the subject. Under the main panel when I select option 2 for AF meter, the AEM is not listed. I selected other and it has values or 10.00 to 30.00. How do I figure out what goes there, or should I leave the default? The manual is not very helpful
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Old 02-01-2008, 08:11 PM   #5
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Yeah, no AEM defaults in the EMU software, but no bother. Just select "OTHER" as the A/F Meter type, and key in the values manually. The first box is AFR at 0v, the second is AFR at 5v. So if you were using a device (and unfortunately you aren't) that was 10:1 at 0v and 20:1 at 5v, you'd put 10 in the first cell and 20 in the second.

And there's the rub. Like I said- unlike the AEM Gauge-type sensor (and every other wideband A/F meter I've ever seen) the output of the AEM 30-2300 and 30-2301 is non-linear. See the attachment, which is page 8 of the manual.

If you configure the EMU in the usual way, by telling it that 0v = 8.4 and 5v = 19.5 (both of which are true) then it'll just draw a straight line (in green) between those points and expect all the other values to fall in line. But with the AEM 2301, they don't. The graph is curved, so when, for example, the mixture is at 14.7:1, the EMU will think that it's actually 17.25:1!

I don't really have a perfect answer. One option would be to lie. Look at the pink line. It's a fictitious reference I just came up with that might work. If we tell the EMU that 0v = 4.6:1 and that 5v = 17:1, look what that does. It puts the straight pink line across the portion of the AFR table that we really care about (between 11.5:1 and 15:1) in such a way that it's close to linear. The gauge will be way off at the extremes, but you're not tuning for those values.

Give it a shot. Maybe it works, maybe it doesn't. Before you start doing any autotuning, just eyeball the computed AFR that the EMU is telling you relative to a direct voltage measurement. I think it'll be close.
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Old 02-01-2008, 08:12 PM   #6
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I think I figured it out if someone could confirm I'd be greatful
The chart that came with the AEM shows Lambda 5v, the AFR range is from 8.50 at 0 to 20.67 at 4.9992 which is the highest value on the chart.
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Old 02-01-2008, 08:19 PM   #7
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Got, thank again...I'm back out to the garage to add the 460 injectors. If you have any links on how to figure lag time for the factory 265CC injectors to the 460 cc feel free to hook a brutha up.
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Old 02-01-2008, 08:46 PM   #8
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If you have any links on how to figure lag time for the factory 265CC injectors to the 460 cc feel free to hook a brutha up.
Lag time was always a bit of a mystery. When I ran the EMU with 440s, I think I had .65 as the before time and .8 as the after time. Neither one had any basis in reality, I think I copied those settings from someone else. But they seemed to work.

Now that I'm working with MS, I think I've solved my actual lag time with the 440s as about 1.2. But the actual numbers aren't important, only he relative difference between them.
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Old 02-01-2008, 11:35 PM   #9
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Thanks for all the help. Got everything installed and working OK. Injectors idle well and run great part throttle. Past about 70% it loads up bad. Guess it's time to do some searches and figure out the rest. I was pressed for time today and you responses helped me git r done
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