Mysterious control box - any ideas

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JohnT
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Mysterious control box - any ideas

Postby JohnT » Fri Nov 10, 2006 8:23 pm

A question for those who have been around a while. We have a black box, with eight wires coming from it, four rotary controls labelled VF, VC, BF and BC. It came with the Green Civic / City project when we bought it from Charles. He commented that we would need it later, but get the car running first. (A good idea!) I have posted a snap shot of it in the Gallery.

Any bright ideas?

Many thanks

John T

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James
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Postby James » Sat Nov 11, 2006 4:13 am

Here's my theory, its a Charles Special by the looks of things.

The V stands for vacuum and the B stands for boost, on for each of the map sensors in a city. As for the F and C, maybe ones addFuel and ones Cutfuel Im not sure on that one. If you take those four screws out and do a photo of inside im more likely to be able to help you.

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Postby JohnT » Sat Nov 11, 2006 8:28 am

Many thanks Bigelboe. Picture of the inside now in the gallery. The wires to the VF and VC controls cluster together, (that is, VF and VC controls are linked) and BF and BC go together. My suspicion is that it goes between the MAP 1 and MAP 2 sensors and the computer, "fooling" the computer about the output of each of the MAP sensors - I understand one mostly signals Vacuum / mild boost settings and the other Boost.

Which would make sense with the V and B groupings on the controls. What do you think?

I must check for colour match on the wires and MAP sensor colours.

John

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James
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Postby James » Sat Nov 11, 2006 8:52 am

It looks liek some way of crudely shaping the map sensor curves, by changing the slope of the map sensor reponse using those variable resistors. I cant quite see the wires properly in that picture if you either want to take a sharper photo or draw a little schematic I might be able to suggest how its ment to be hooked up.

Map sensor B signal is a light blue wire, and I believe map sensor a is a white wire with a blue stripe.

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Postby JohnT » Sat Nov 11, 2006 9:31 am

Bigelboe

I'll both draw a scematic, and also take to it with a multi-meter and see what it is doing in terms of black box function. My suspicion is that it picks up the 5V supply to the MAP and the sensor reading then biases the MAP reading either up or down using the signal ground or the 5V supply.

About to go lay tiles at Chris's place - not my favourite occupation - so will get stuck into the magic box later in the day.

If it can cut the dreaded boost cut brick wall would be good - especially if it can be set to allow normal operation when not feeling playful..... (or is that pay full with the radar cameras we have now..) We're hitting the 15psi cut out at around 3.8 - 4.2 k rpm so would be good if we can.

John

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James
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Postby James » Sat Nov 11, 2006 11:49 am

Sorry I wont be much more help today, last exam this morning and on the turps already.

Getting rid of boost cut would be good, but not possible with a basic variable resistor. If you have enough skills to make a circuit on proto board I can hook you up with a plan for an FCD. Its easy to set up with an on/off switch too.

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JohnT
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Postby JohnT » Sat Nov 11, 2006 2:05 pm

Bigelboe
"if you have enough skills to make a circuit on proto board" - well, once upon a time as a graduate student I used to design and make hardware for PDP DEC 8 & 11 computers in our lab, and make the odd bit of instrumentation up. (Mind you, that was about the time our EB1 was being made...) So yes, would be good to have a circuit I could make up to boost cut defend. Veroboard job or do you need to make up a PCB?

Hope the exam went well, pleased to hear you are on the alcohol - make sure you drink plenty of wine and keep Chris in work at McLaren Vale.

You studying engineering? Elec or mech? My current day time project is a proposed 266 MW gas turbine based power plant ....

John

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James
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Postby James » Sat Nov 11, 2006 2:54 pm

Yehp Its a veroboard jobbie, Im not sure who Mclaren vale is but we are drinking plenty of the local brew. Im 3/4 of the way through a Mechatronics degree so its got a bit of both realms. My cousin is a leading power plant engineer in aussie (I think), his name is Peter Costello (not the minister) wonder if youve heard of him?

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Postby Colza » Sat Nov 11, 2006 3:09 pm

From my experience with attempting to intercept MAP signals and edit them its quite hard. I all I achieved was something that tripped an error code about 30 sec after turning the engine on.

Damn ecu thinks is so smart :roll:

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Postby JohnT » Sat Nov 11, 2006 5:14 pm

Well, I've just posted a diagram in the gallery but forgot to put the values on the potentiometers - they are all 10k ohm, linear. So when they are centred pretty well at 5kohm per control.

Basically a pair of identical layouts, signal - ie white on VF control comes into one end of the 10k pot, far end of the pot goes out to the "centre" variable resistance setting of the next pot (VC), while the variable output of the first pot goes of to a yellow wire, the second pot is fed by a purple wire at one end, a grey one at the other. The other wires, are pink, variable off to red, next pot fed by blue and green an dits variable point fed by teh tail end of the first resistor. No connection between the "V" controls and the "B" controls.

Some match to MAP wiring, MAP 1 on our beast is pink, gree, white; MAP2 is yellow, green, blue and the fuel adjust pot is green, brown, yellow.

So no absolutely obvious match up.

Anyway, any ideas appreciated. I have sent Charles a PM, but don't know how often he is online nowadays.

John


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