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MK. II RACING
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Discussion Starter #1
I just had a friend give me his black box FCD that he had on his 93T. He got the ATS ECU/ct27 deal for his MR2. So, he no longer needed the BILLWOT FCD. I currently have a zenier diode placed with my TwosRus MBC set at 14.5psi. I would still like to have Fuel Cut for safety which is why I accepted the FCD from my friend. The question I have is this (seeing how my friend can't remember)...

When turning the screw on the 15-turn cermet to adjust the fuel cut, which direction of the turn does what?? If I turn the screw on the cermet clock-wise (turning it in all the way) does this lower the FC to its lowest setting, OR, does it increase the FC to its highest setting (around 18psi IIRC)??

This info would be quite helpful before I start "adjusting" it to around 16psi. Thanks in advance.

Daniel
 

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Turning the screw on the POT changes the ammount of voltage that is dumped to ground.

If you want fuel cut to initiate at 16 psi, then you need to apply 16psi to the pressure sensor, and adjust the POT until it reads output voltage of 4.4v @ 16psi.

(I think clockwise will raise the fuel cut level.)
 

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I don't remember which way to turn it, but you cand determine it very simply with an ohmeter.

With the FCD disconnected any other circuitry, turn the pot and monitor resistance between T1 and T2. Increasing the resistance between these terminals will increase the FC setpoint.

Or you can just set it with an ohmeter using the values here in the instructions.

http://toymr2.tripod.com/fcd.html

bill
 

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MK. II RACING
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Discussion Starter #4 (Edited)
From looking at how the FCD works, my thinking was along the lines of what MISTER2 said. I already had the instructions downloaded. Was hoping not to have to get out the ohmeter (being lazy!!). But, thats okay, I don't mind. Thanks for your replys MISTER2 and Bill!!!!

Daniel
 

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mr2boost said:
From looking at how the FCD works, my thinking was along the lines of what MISTER2 said. Was hoping not to have to get out the ohmeter. But, thats okay, I don't mind. Thanks for your replys MISTER and Bill!!!!

Daniel
Your ohm meter and volt meter are not the same instrument? :confused:
 

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mr2boost said:
From looking at how the FCD works, my thinking was along the lines of what MISTER2 said. I already had the instructions downloaded. Was hoping not to have to get out the ohmeter (being lazy!!). But, thats okay, I don't mind. Thanks for your replys MISTER2 and Bill!!!!

Daniel
There are 2 different ways to set it, but bith require a meter.

bill
 

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MK. II RACING
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Discussion Starter #8
Yeah I see that
2340 ohm's = 16psi and..
4.7v = 16psi

One thing I do understand is thses values. THANKS again fella's :thumbup

Daniel
 

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mr2boost said:
Yeah I see that
2340 ohm's = 16psi and..
4.4v = 16psi

One thing I do understand is thses values. THANKS again fella's :thumbup

Daniel
Close. 4.4v = Fuel Cut ...the PSI figure that coresponds to that depends on how you set the POT.
 

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MK. II RACING
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Discussion Starter #10
Okay, MISTER2 I understand that. That makes a little more sense to me now. I thought that looked like FC value. THANKS!

Daniel
 

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billwot said:
I don't remember which way to turn it, but you cand determine it very simply with an ohmeter.

With the FCD disconnected any other circuitry, turn the pot and monitor resistance between T1 and T2. Increasing the resistance between these terminals will increase the FC setpoint.

Or you can just set it with an ohmeter using the values here in the instructions.

http://toymr2.tripod.com/fcd.html

bill
For some reason Bill when I adjusted mine to the 17 PSI Ohm value I was hitting Fuel Cut (talk about SCARE me the first time...) before 12PSI. I had to adjust it substantially.
Maybe the resistance varies a lot from car to car or maybe mines weird.
I did double check all the parts and all was hooked up and the correct values.

I tied my boost gauge into the line just under the boost sensor.
I then unplugged the line from the little filter thingy and put a small portable aircompressor over the line, it happened to be the same size as the valve stem thingy on the compressor.
quickly I switched the compressor on and off (its a small portable air compressor and pumps up tired kinda slow) till I reached about 19 PSI on my gauge on my dash.
It would slowly bleed off so I waited a few minutes until it was about 17.5 PSI and I hooked up my meter and adjusted it to 4.4 volts.
So now I KNOW FC is around 17-17.5 PSI.

Going by pressure and measuring voltage is best as mine was weird and was way off when I tried to do it by OHMs only...
 

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MK. II RACING
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Discussion Starter #14
Man, I'm brain farting too. Oh well, was posting all this from work (firestation) and we kept getting toned out and then disregarded. Bill is right 4.4 volts is FC. I like the way you described setting it kurdain, I think I will try that first.

Thanks all! :thumbup

Daniel
 
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