MBE ECU and battery voltage compensation map

[knowley]

 

Hello,

 

Could anybody having a MBE 967 Ecu and the connection loom to Easymap tell me what is the battery tension reading (in Easymap) compared to the actual battery terminals reading (measured with a voltmeter)?

 

Thanks

 

[dannylt]

Surely the idea is that it's accurate, and any difference will be down to the individual sensor, i.e. different on each car.

 

[rj]

My Stack dash indicates quite similar to the readout in Easymap.

 

There is no external sensor neither for the ECU nor for the dash.

 

I reckon the only thing the voltage is used for in the ECU is to slightly alter the injection time as the injector will open faster when the voltage is higher. I have never seen problems on my own car with this, but the voltage is fairly constant. It made difference though when I changed from a Rover alternator to a Brise, and at that point the voltage did change with 0.2V. I monitor the Lambda quite frequently.

 

/r

[dannylt]

What do you mean "external sensor"? They're both wired to the battery, and therefore the sensor is internal. The voltage drops quite a lot when cranking especially, but also if charging or not.

[rj]

I've never run my car whilst not charging - or at least not been hooning it as there has been a warning light on!

 

Of course there's a significant difference in the voltage whilst cranking, but this already is a different map, so nobody would be able to tell if the difference in fueling came from the cranking map or from the supply voltage correction.

 

I just wanted to point out that the voltage sensors - and regulators - are internal in the units, and that it therefore couldn't be a dodgy sensor, hence the comment about internal sensors-