You didn't look to hard - they are only two pages of articles in the workshop ;) (I will get this moved to the knowledgebase soon)
http://www.lexusownersclub.co.uk/forum/ind...showtopic=1161&
Do a search on the web for o2 simulator. You should be able to find some.
A better solution would be to get it working correctly still using an O2 sensor. Maybe you need to take it somewhere else?
I think the standard F-CON is designed for turbo engines. The S-AFC compares with the HKS Super AFR. Both modify the airflow sensor input into the ECU to make fuel corrections.
Both would need to be set up on a rolling road. There is not much difference between the two. The Apexi one looks much better and displays more information however the HKS has finer adjustment (11 points/50 rpm steps compared to 8 points/500 rpm steps)
Creating an air leak will increase the amount of air not decrease it. The MAF sensor will not know about the extra air getting in and therefore won't add any extra fuel. If the O2 sensors are working correctly though the ECU will start to add more fuel to compensate.
Yes the O2 sensor should be tested for reaction as they can become slow.
With the sensor oscillating quickly, averaging around .45v a quick squirt of propain will bring the voltage up very quickly and then should go back. Then disconect a vacuum line and the voltage should drop.
If the problem is the engine is running too rich then yes it may help. Keep an eye on engine temp.
There must be reason why the CO2 is high though:
dirty air filter
dirty MAf sensor
Cat failure
cat been removed.
ECU been modified.
Lexus/Toyota use different intervals in different countries. In the UK the cambelt interval was 60,000 (63,000) miles up to the year 2000 now it's 100,000 miles