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Microtech Noob Question About LT 10

Old 07-16-08, 12:18 PM
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Noob Question About LT 10

I am new to the RX-7 world and was hoping someone could help me with a question I have regarding the operation of the LT 10. I have searched on this but couldn't really find an answer.

Is it any big deal to install an LT 10 in a car with air conditioning? For instance, if you have tuned the engine to operate efficiently (and I am not looking at tuning for maximum horsepower - just decent economical operation), what happens when you are idling at a stop light and the A.C. compressor kicks on? Does the Microtech compensate for the increased load?

Engine is basically stock but running non sequential turbos with increased intake and exhaust efficiency.

Thanks in advance for any help you can give me.
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Old 07-17-08, 10:28 AM
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If wired correctly it can compensate for air condition.

Im assuming you have a FD?
If so. buy a powerfc, much better suited to a street application FD.
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Old 07-17-08, 09:05 PM
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can you run ac with lt8?
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Old 07-17-08, 10:55 PM
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LT 10 Wiring Diagram

Thanks rx72c

I didn't do the original installation. I went to the Microtech website and they offer wiring diagrams for all models except the LT10. Is it available? Will that diagram, if I can get it, show the correct terminations which nned to be made.

A.C. never worked before I got it, so I don't know that it is incorrect.

By the way, can you give me a little more info on the Powerfc?

Thanks,

Jeff
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Old 07-18-08, 06:11 AM
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They have the general LT10 wiring diagram here:
http://microtechefi.com/microtech-wiring.php#3
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Old 07-18-08, 08:06 AM
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LT 10 Wiring Diagram

Thanks Broken09 for the wiring diagram.

So it looks to me, and I admit I don't know much about this, is the only input back into the controller which may sense a different A/F ratio due to the increased load from an air conditioner compressor would come from the oxygen sensor. Is that correct? So if the oxygen sensor is working properly then the Microtech will respond to the load?
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Old 07-19-08, 11:57 AM
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microtech is not a closed loop ecu. does not respond to afr reading.

if you want your microtech to recognise the ac. you must wire an input(blue/red)wire and that will tell the microtech the a/c is on via 12v signal and add more fuel to compensate.
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Old 07-19-08, 01:38 PM
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Aux Input #1?

Thank you for the response. So the only blue/red I see which might be a possibility is Aux Input #1. Perhaps tie into the compressor clutch power? I imagine that whenever the A.C. system engages the compressor clutch it does that with 12v power. Is that the point that supplies the input to the LT10?

It just seems to me that the demands on the air fuel ratio are going to be different at idle and at 75 m.p.h. In other words, if I program more fuel so it runs well at idle, then it will supply more fuel than it needs at cruising speed. Or am I missing something?

It doesn't seem as if the Microtech is very "intelligent" but maybe this is the way all of them operate. Are there any closed loop ECUs?

How did Mazda take care of this with the stock ECU?

Thanks again for the information.

Jeff
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Old 07-20-08, 05:42 PM
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thats correct.

The microtech isnt very intelligent.
It is a computer for a race car that lots of people fit to street cars and just deal with the disadvantages.
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Old 07-20-08, 11:03 PM
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So Who is the Smartest ECU on the Block?

For the application I want (maybe want is not the best way to say it). For the application I will probably end up with -

non sequential stock turbos
3" through and through exhaust
and a mildly ported engine
boost limited to a relatively low 10 to 12 - hopefully will be able to limit the creep

and would like decent drivability,
would like to get the A.C. working,
and wouldn't mind decent gas mileage,

is the powerfc still the best choice as previously suggested?
is there a better choice?

Thanks,
Jeff
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Old 07-21-08, 03:32 AM
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power fc still easily the best choice. has more tuning points, can run leaner afrs with better injector resolution. and if you ever change your mind can run the turbos in sequential.
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Old 07-21-08, 07:32 AM
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Last Question - Hopefully

Would it be difficult to change from a Microtech to a Powerpc? I assume the Microtech harness was spliced into the existing Mazda harness. And the Powerpc just plugs into the existing Mazda harness, so I would need to unsplice the Microtech plug and restore the Mazda harness? Is the Mazda plug available anywhere?

Thanks for all the help,
Jeff
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Old 07-21-08, 05:53 PM
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if your mazda harness is still in the car and unbutchered just plug it in.
but if its butchered you will need a new factory oem loom
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Old 07-22-08, 08:46 PM
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Thanks everyone for the information!
jeff
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