air/fuel ratio gauge wiring

D

DodgeT

Guest
got an autometer afr gauge which im gona wire in tonight..

it has 3 wires off the back;

red
black
purple

which im guessing is

red = live (ignition live?)
black = earth
purple = reading off ecu,

if you have wired one in, or know where the purple wire goes in relation to the ecu, could you please tell me?

once sorted, ill do a quick "how to" similar to http://forum.gtiroc.com/phpbb2/viewtopic.php?t=14802

thanks.
 
M

MORRISMINOR GTI-R

Guest
yeh i could also do with knowing this as my new a/f gauge should be here by weekend. :D
 
G

geetee

Active Member
Bear in mind that the standard sender on the R does not produce the correct voltage range for these AFR gauges :(

Cheers
GeeTee 8)
 
M

MORRISMINOR GTI-R

Guest
is there no way around this as ive noticed quite alot of other members have fitted and used them succesfully without adding a wideband sensor :?
 
G

geetee

Active Member
Quote from other thread linked above
****************************
>Standard R sensor is fine i believe for monitoring but not speceifc enough for tuning.

The last green light on the guage = 1.0 volt

1.0 volt = 7 % co approx = 11.89 Air fuel ratio which is nice and rich on full throttle.

On part throttle once the engine is running and warmed up the sensor will flick between rich and lean indicating a AFR of 14.7 i believe.
*******end quote*************

This being the case - can you use an S-AFC (or the like) to lean out your fuel mixture a little so instead of the gauge showing full rich on full throttle - it's on the last green.

Or do we not have enuff confidence in our Lamda sensor accuracy?

Why does the gauge flick from rich to lean and back all the time on part throttle - is this because the R's ECU is a bit ham-fisted at maintaining a set AFR at a steady rpm??

e.g. oooh that's a bit rich... better reduce the fuel...... ooh bugger now it's a bit lean... better increase the fuel.... oooh that's a bit rich better reduce the fuel.... ooh bugger now it's a bit lean ..... better increase the fuel etc etc etc etc

Perhaps it's just 'the way it is' !

One last question - does a wideband sensor give 1.0 volt at 7% co also?

Cheers
GeeTee 8)
 
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