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Wiring/MFRU diagram for 1996 K-series 1.4 Supersport


Mankee

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Does anyone have any wiring info for the above car please, as I know there are a few floating around in the club, whether they've been converted with bigger engines or not

I already have the scanned (hand-drawn?) diagram for injected cars and there is a good diagram on the internet for my MFRU, a yellow label YWB10022. Both are useful but I've reached a slight stumbling block during my task of simplifying the existing loom before I build a fresh loom.

After some inspiration from revilla's Low Flying article, I wanted to get rid of the MFRU and replace them with two simple relays, one for the fuel pump and one for the starter solenoid. These two modified circuits work fine, as I have fuel and the starter motor spins. However, unlike later cars, it seems that the main relay in the MFRU actually serves a purpose, as it seems I now have no spark!

I have a few spare large wires from the output side, mainly brown/pink. I assume that one of these is my missing coil feed. The question is which one and whether it needs to be controlled by another relay or if I can use one of the other lives?

If I need another relay, it hardly seems worth the effort to remove the MFRU!

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As you have found out there are some variations in the use of the 4 relays within the MFRU.

If you find an ECU pinout diagram & follow the wiring into the MRFU (& out again) you can check what the various relays do (use a multimeter to confirm continuiity). My car is a 1994, originally with the old 1.4 K series. 4 relays were used controlling lambda sensor heater, fuel pump, starter & injectors (IACV & charcoal cannister).

The lambda sensor, IACV & charcoal cannister were removed a while back, & I installed a separate relay for the starter for obvious reasons.  However when I was getting a misfire, & odd fuelling problems, I got rid of the MFRU in favour of standard relays to just control power to the fuel pump & injectors.

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OK, so the plot thickens some more, as I've spent a little more time with the multimeter to probe the connections between the MFRU and the ECU (Emerald). Using the same numbering convention for the MFRU's output plug (big 8-pin) as per below:

http://www.tom-seven.stillgame.ch/Main/MFU.htm

I needed to work out what my brown/pink wires from pins 1, 3 and 8 actually do. This is what I've discovered:

  • Pin 1 goes to Emerald pin 28: this is the switched supply, so all good
  • Pin 3 goes to Emerald pins 1, 23, 24 and 26, which are injector drivers 4, 2, 1 and 3, respectively: this is the one I'm having trouble with
  • Pin 8 I have no idea where it goes, so need to do some more probing

So pin 3 on the MFRU goes to four injector drivers in the Emerald? But the injector drivers should be switched earth outputs, unless someone has configured them weirdly? I just cannot seem to get my head round this one. *curse*

More probing between the injectors and the ECU I think.

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  • 1 month later...

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