SLROC Forum

Hi

I am currently rebuilding my 90 with a 3.9 v8 and I read somewhere that you dont need to use the Lambda sensors
as I dont intend using the cats or the original manifolds is this correct or do I have to fit the sensors in my manifolds.

thanks

Sam 

Hi,

Depending on the ECU (PRC8747 does not need tuning resistors, but PRC 7081 does)
the 3.9 efi can work without lambda sensors (called open loop), but you need to change the tuning resistor to the "green" 470 ohms.
the tuning resistor is in the loom somewhere near the ecu connector it is 2 wires and a connector, with 2 wires going into a flat clearish plastic sleeve with a resistor inside.

I think the cat ones (with lambda sensors) are white or some other colour.
I believe there are 4 ranges of resistor
3900 ohms  white,European catlyst
910 ohms yellow, sudi non cat
470 ohms green, uk and eu non cat,
180 ohms red, australia and rest of world


Cheers

Stephen



 

Hi

Thanks for the reply, I will have a go.

regards
Sam

Great info