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yes, you need the female part and wire it according to the Doctronic schematics for wideband ECUs. In Europe at least, Doctronic sells the E, C101 and the lambda connector.
Or cut it off and wire in any other connector you can source. But I prefer to keep the engine loom as OEM as possible.
 

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Discussion Starter · #22 · (Edited)
Am I correct in understanding that the C101 and E terminal plugs should be wired on the 85 relay terminal? Isn't this usually a ground and should not be connected to anything but star earth point?

And shouldn't terminal 30 for the main relay be connected to the constant 12V supply, i.e. the battery? In the diagram it's connected to terminal 87 which I thought was an output, not input.
 

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see page 2 of the Doctronic schematic pdf a few posts up.
The only ground you connect is from battery to the engine block and the engine loom with its ground strap to the cam cover or OEM intake manifold. No other grounds are used that you have have to route.
Then you feed battery 12V to the main relay switch input. The main really then provides "switched 12V" to the C101 once activated by the ECU.
You can skip the brake pedal switch. If you use a Hondata or Doctronic ProK ECU, as you can disable this function.
Ihr ECU sees ignition 12V from your ignition switch to E9. this then triggers the ECU to activate the main relay. This then powers the starter relay and the fuel pump relay.
The starter trigger is an other switch than then triggers the starter relay though C101 Pin 16.

It is really not complicated wit the doctronic schematic page 2.

For RPM, you can hook up any rpm gauge. The frequency output can be adjusted in the Hondata or Doctronic ECU.

30 and 87 are interchangeable on a relay. The Doctronic schematic states no numbers BTW. It just shows the switch portion of the relay. There is no polarity unlike with a solid state relay.
 

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PRA, PRB and PRC are K20 types.
if you are not competent in these type of electrics, I suggest you get a K20a2 or K20a (missing VTP sensor) engine loom such as one from an RSX-S and the ECU with it. Then it all works as in the pdf. Easy as thant and no engineering required.

If you attempt to reinvent the wheel, you need to sort it out itself. I don't have any other schematics than the RSX-S and the cars I put the engine in, i.e. a MK1 Lotus Elise or a S3 Lotus Exige.
I don't understand half the model designations in the USDM either, such as Civic Si etc. as we in Europe get them with a different name or don't have these K24 engined models at all.

I recently helped to drop a K20a2 into a 2004 Lotus Exige originally using a Toyota 2ZZ engine. The MWR conversion harness was next to useless for a european spec PRA ECU and on top of it, was not well thought through even for its original application on US spec PRB looms and US spec cars. It took me about 3 full days to document each an every cable to the ECU, the conversion loom and how the Toyota loom works, coming up with a schematic and rewire everything. And I roughly know what I am doing. If you are not into it, I'd say don't try or take your time.
PS are you sure the knock sensor signal runs though the C101 connector? why should it? These run straight from the sensor to the ECU though the engine loom.
Lotus I attempted to send you a pm about your experience with the MWR harness. I will be doing a K-swap in an Elise also.
May you can PM me?
 

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Discussion Starter · #25 · (Edited)
On the last page there's a legend of the relay:

104436

Is it up to me to wire 87 and 30 for the fuel pump and fan relays? They are not connected to anything on the diagrams.

I'm trying to make this adapt to a test stand that is already pre-wired. However, this is prewired toward carbureted engines and not EFI. I have the schematics of that I could PM you if you would be so kind to look over.

I think I'm getting there. I have the parts on order and will inspect everything to see if I can figure it out.
 

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yes, up to you to wire a fuel pump and fan relay if you recreate a car loom to connect to the engine loo, though C101 and E.
You can send me the schematics.
 
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