Call All Electrical guru's

[leeroy_25]

So guy's, I have a idle control issue with my microtech ECU where it is essentially a bit basic and does not have some quite key functions. So I want to try and plug something in to create a work around for the main issue I currently have. That is poor idle due to voltage drop when any electrical loads are applied such as fans.
The work around I want is this. I want a wire something in off the back of the alternator or any other 12V wire I guess that reads the voltage which under normal running will be around 14.2 volts with a good battery. if the voltage temporarily drops down to say 13.8V when a load is switched on I then want this to flip a switch which will allow a 12v supply to be sent to an input on the ECU. Then when the voltage picks back up the switch will flip back and close off the 12v source to the ECU. I hope that makes sense. I think this should also only happen when at idle so I guess that means wiring a microswitch onto the throttle pedal or throttle body that is on/off when the throttle is closed.
Can anyone advise if there is any off the shelf item that will do this or if I need to make something and if so what components am I looking at?
One other thing is ideally I want to be able to adjust the voltage that the switch flips at in order to fine tune the point at which this needs to happen.

Thanks for any help.

Cheers
Lee

[boosted]

Hi mate. Confussed some what why dont you just raise the idle setpoint so that any idle load like fans cutting in etc the car has stable idle? So turn everything on and set base idle around 850 rpm and go from there.

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[clive]

What Jon says should solve your issues, however have that same issue with the race car and know this is due to the huge current draw of the Bosch 044 fuel pump so if you have one fitted this is the likely cause of what you are seeing.

[leeroy_25]

Hi Guy's thanks for info.. The dip in rpm is quite minimal when the loads are switched on. it is more the drag down on the voltage which effects the injectors I think as the ECU does not have proper voltage compensation. bit of both though for sure. I was going to raise the idle a bit to try and help but I don't think that alone will solve the issue. Also when you put the loads on the rpm normalises after a few seconds so to try and set idle that way would be quite a trick.
Fuel pump wise I have one of those neat new walbro 450lph ones... Well will see if it keeps up when I get it wound up on the dyno!

Cheers
Lee

[clive]

Fuel pump wise I have one of those neat new walbro 450lph ones... Well will see if it keeps up when I get it wound up on the dyno!

That will be whats drawing off your power then. I looked at one of these as I thought it may draw less current than an 044 but there is no difference