3.6 Transplant issue with the o2 sensors.

[Kroggers]

Because the signal from the pre-cat o2 sensors is used by the dme to adjust the air / fuel mixture. At the moment my car is running in open loop, which is not giving the best ratios at best, and will make the car run lean at worst.

[blue62]

Originally Posted by Kroggers

Because the signal from the pre-cat o2 sensors is used by the dme to adjust the air / fuel mixture. At the moment my car is running in open loop, which is not giving the best ratios at best, and will make the car run lean at worst.

Yes the DME uses the signal from the O2 sensor to adjust air/fuel mixture.
But it does that to regulate the temperature of the catalytic converters.
O2 sensors and fuel trims are about catalytic converter performance.
Not engine performance or power.
If this is a race car I assume you removed the Catalytic converters.
If you did remove the catalytic converters then your O2 sensors are serving no purpose.
Open loop fuel maps will work just as well or possibly better for power.

14.7-1 is the best ratio for lower emissions.
Not the best ratio for power.

Narrow band O2 sensors as used in these car are not very accurate at anything but 14.7-1
Also they don't even measure outside of about 1% away from 14.7-1

[Kroggers]

Originally Posted by blue62

Yes the DME uses the signal from the O2 sensor to adjust air/fuel mixture.
But it does that to regulate the temperature of the catalytic converters.
O2 sensors and fuel trims are about catalytic converter performance.
Not engine performance or power.
If this is a race car I assume you removed the Catalytic converters.
If you did remove the catalytic converters then your O2 sensors are serving no purpose.
Open loop fuel maps will work just as well or possibly better for power.

14.7-1 is the best ratio for lower emissions.
Not the best ratio for power.

Interesting, and good to know.

i do still have racing cat converters, as they are stipulated in the regulations. But I am focused on performance of the engine and not the converters. So you are saying that I do not need to worry about the adaptation of the fuel mixture by the dme?

I thought the pre-cat o2 sensors were to manage fuel mixture and the post-cat o2 sensors were for emissions?

[blue62]

Originally Posted by Kroggers

Interesting, and good to know.

i do still have racing cat converters, as they are stipulated in the regulations. But I am focused on performance of the engine and not the converters. So you are saying that I do not need to worry about the adaptation of the fuel mixture by the dme?

I thought the pre-cat o2 sensors were to manage fuel mixture and the post-cat o2 sensors were for emissions?

If you have to have Cat converters then you do need adaptation of fuel mixture so that the Cat converters function correctly.
The air /fuel ratio that allows Cat converters to work is not the same air/fuel ratio that makes power.
You can't have both at the same time.

Pre-cat O2 sensors are to manage fuel mixture "for Cat Converter function" Post cat O2 sensors monitor Cat converter function to make sure pre cat O2 sensor are doing there job.
They are both for emissions.

Google: Catalytic Converters find the Wikipedia article on Cat Converters.
Read the whole article. Pay particular attention to the segment on "Three way Cat. Converters".