1UZ with no sub O2 sensors question

[Mat Grant]

Hi all,

Got a question about O2 sensors - I'm fitting a 1uz soarer engine into an old lotus. I have the soarer manifolds with the O2 sensors but not the sub O2 sensors post the CATs. My car will not have any CATs.

I intend to use the primary O2 sensors in the manifold, and not use the sub O2 sensors. Can anyone tell me:

- Can the function of the sub O2 sensor be simulated with a resistor from the sensor wire / ECU pin to ground?

- If so what value of resistor do i need to install in place of the sub O2 sensors to make the ECU think the exhaust gas is how it should be post a CAT?

- Assuming working primary O2 sensors, and a standard working ECU, will the engine run ok like this?

Any help or comments appreicated. Thanks, Mat.

 

[Beezer]

A Soarer v8 engine doesn't have a 2nd set of o2 sensors. It only has primarys & cat overheat sensors. I think you can safely delete the overheat sensors.

 

[Mat Grant]

Hi Beezer,

Great stuff - thanks for the reply. One less thing to worry about! I'm going to try to fit universal O2 sensors with the heater connection, i've been told it works more reliably when heated, and gives better running.

Cheers, Mat.

 

[Mat Grant]

By the way - the ECU wiring diagram I have got has sub O2 sensors on it - it is a PDF from this site, it's labelled as "1992 SC400" a PDF in two parts. But this diagram also shows the O2 sensors (all 4) as 4 wire, whereas the ones on my car are 1 wire.

The HTv leads on my enigne say 1991, so guessing that's when it was made. Have you got a wiring diagram for the 1991 soarer?

Cheers, Mat.

 

[zen]

only use the diagrms on here as a guide..they are not for uk models though are accurate to a point,ie the ones i use for my 95 ls400 engine in my old range rover are good except the colours on some wires are wrong...

if using heated o2's make sure same output voltage etc...otherwise ecu wont like it..

sub o2s the ecu can do without (if originally fitted)resistor dont work as an emulator, but worst case you just get fault codes in ecu for sub's which dont effect running..

what lotus??

 

[Beezer]

By the way - the ECU wiring diagram I have got has sub O2 sensors on it - it is a PDF from this site, it's labelled as "1992 SC400" a PDF in two parts. But this diagram also shows the O2 sensors (all 4) as 4 wire, whereas the ones on my car are 1 wire.

USA spec SC400 had 4 o2 sensors as far as I know. Your Japanese Soarer engine only had 2.

 

[Mat Grant]

Thanks guys - yes the soarer my engine came out of is a jap import (no official soarer imports as far as i know) so i'm guessing the diag on here is for the USA spec one(?)

Anyway thanks for the info.

I got the idea fro the heated sensors from reading a thread where someone in the UK had swapped out the stock 1 wire O2 sensors for 'universal' 3 wire heated ones, and the car ran a lot better.

Plus my O2 sensors got wet and i presume they are knackered....

Cheers, Mat.