Adding Lambda probes to Lucas 14CUX on non-cat car

[kistinie]

Hi,

as far as i understood there is a strong benefit to install oxygen sensors to non catalysed car.
It gives better air fuel ratio on each bank and for us in countries using E85, it helps a lot to be easily flex fuel just playing on injection fuel pressure.

I have two cars to convert, both 3.9 EFI, a GINETTA G33, and a classic range rover.

Just to be sure, i started looking at the wiring of the G33 and found no blue wires in the actual harness as the following documents suggest it should be the case.

It means i guess i have to go to the main connector and add the missing cables ?
Same question for the 1990 RRC, nothing is supposed to be found ?

If you already did this upgrade, how did you solved this cabling aspect ? Is it practical to open the connector and add the missing cables ?

https://www.legionlandrover.com/manuale ... ection.pdf

Thank you !

regards
François, from France

[GDCobra]

Hi, François

Although a fully closed loop, lambda equipped system may offer some advantages I'm not sure that will be the case with the 14CUX. The reason for this is that this system only uses narrowband sensors so can only monitor stoichiometric values so has limited capability. Arguably the trim values calculated when in this mode will then be used to calculate the fuelling at other times but the added complexity may outweigh any potential gains.

I was tempted to do this on my car a while ago but got talked out of it.


What are the blue cables you mention? Are these the ones for the tune resistor?
If so then you may find that the resistor is 'hidden' inside the loom, would be a good idea to check if the wires exist in the ECU plug and if so whether there is a resistance on them (indicating a resistor present). If not then it is likely that the program in your ECU is set up not so use an external resistor to switch the tune. Some regions were set this way, I believe this was mandatory in the USA, but this would normally only be if the system WAS using lambdas and CATs. If this is the case then simply adding a resistor won't do anything. However all is not lost!
This setting is controlled by the values stored on the EEPROM chip so it will be possible to alter it by plugging in an EEPROM which does have this feature enabled. Does your ECU have a permanently soldered EEPROM or a plug in type?

[kistinie]

Thank you,

i have a resistor, a green.

As far as i know there is only to change the resistor and plug the probes.
I do not know if the eprom is soldered or not.

My main concern was to know the best option to add the missing wires that are both supposed to be blue

[kistinie]

So now the narrow lambda problem is solved as you have on the market wide band with narrow output :

[GDCobra]

Are you going to proceed with the modification? Presumably you will be fitting 2 of these sensors?
Seems like a significant amount of work and expense, would it not be cheaper/easier to simply fit the OEM sensors for a 14CUX equipped vehicle?

[NZ RRC]

Hi all,

Few years have gone by and I was just wondering if there were any updates on this?

[Ian Anderson]

I ran a 3.9 with 14CUX and lambda sensors and no cars in my GT40.

The engine was extensively worked over by John Eales and it had a JE102 cam which had huge overlap and half inch lift

Tried numerous tune resistors and 3 different ecu’s and it always had a bad dose of kangaroo between 1200 and 2000 rpm at light throttle……I learned not to drive in this rev range and would run it at higher revs in a lower gear.

Never overly worried about consumption….track time around 6mpg and best ever about 30mpg stuck in a long slow traffic jam at about 50mph which was just over 2000 in 5th gear.

If I was to do it over I would but a carb on the top and live with that.all the electronic stuff did my head in.

Ian