I am wondering about the accuracy of our narrow-band o2 sensor and knock sensor. I monitor both. For AFR i get numbers like people have referred to here - 11 AFR for wide open throttle. But I was reading a persons post about narrow band and they said all you can tell is rich, stoich, lean. When I monitor it, it moves in small increments, which indicates to me it is measureing fine differences and hopefully accurately.

I have never seen my ignition retarded due to knock. Since it is winter and octane requirements are lower, I have even run regular. To see if it knocks I will floor it at 3,500 rpm and even run it up to redline and not hear nor measure knock. I know I can't trust my ears; can I trust the sensor?

 

Supposedly the knock sensor in this car is more of a "oh ****, you already have problems" sensor. It's not to be trusted to protect the engine.

 

You can run reg in the winter as long as your car is not HOT. I can watch the water temp gage and know that once it goes over 190F not to ask for WOT. The rotary will give a pre-ignition sound similar to a piston engine at first then if pushed further you get the MIAC sound. It sounds like a large metal can with a metal marble in it shaken hard and fast. If you let this happen you are damaging your engine. One thing we have all learned here is all stock rotaries are not equal. Some can run reg year round some barely get buy on prem gas. If you get a hot carbon spot in your engine you could have pre-ignition problems.

 

The factory front O2 sensor is NOT a narrowband. Only the rear O2 sensor is a narrowband.

 

why cheap on gas ?

 

Not concerned about the difference in price. I understood that too much octane can lead to carbon in general (no background with rotarys). So I thought i would try to cut back. I'll probably go back to prem because I can get non-ethanol prem.

 

A tank of regular costs $39. A tank of low-octane costs $35.
Gas is cheap, motors are expensive.

The OE wideband is accurate from 11:1 to 20:1.
The knock sensor is completely useless.

 

I am glad to hear from two of you that it is wideband and accurate. By spring I hope to have software that can optimize it.

Important to know not to count on the knock sensor. My ears aren't that good anymore that I trust them. Ok, back to prem!

 

In the older days, Mazda actually wrote it in their manuals saying that do NOT use high octane gas cuz its harder to burn and you get more carbon deposit that way.

but Renesis needs it so ...

 

I have read that the compression ratio on the older engines was a lot lower than the renny. If this is correct, it is the likely reason for the lower octane recommendation.