Corvette Z06 Forum banner
1 - 5 of 5 Posts

·
Registered
Joined
·
467 Posts
Discussion Starter · #1 ·
For the people tuning with MAFTs, how are you getting your A/F ratios?

Stock O2 sensor, i.e. via autotap or Ease -- Is this safe, stock O2 sensors aren't very accurate at WOT?

Dyno tuning with wideband 02 -- Great for when you're on the dyno, but what about varing street driving conditions like really hot or cold days... and what about at track events?

On-board wideband 02 -- Great for real-time monitoring, especially at track event, but they are big bucks! Here's a nice one for $1000 (list) http://www.motec.com/plm.htm

Some other way?
 

·
Registered
Joined
·
803 Posts
You're right, the wide band sensors are expensive. I have been told that the power supply to maintain the proper operating temperature is what makes them so costly.

I have used stand alone GM OEM sensors on drag race cars with a data logger. I recorded the raw milivolt signal. I found the data accurate and useable but you do need to do a little RMS smoothing and interpreting.

Some pro teams use a Briggs & Stratton motor for O2 sensor calibration and understanding.
 

·
Z06 Power Adder Authority
Joined
·
3,265 Posts
Roger Ramjet said:


I have used stand alone GM OEM sensors on drag race cars with a data logger. I recorded the raw milivolt signal. I found the data accurate and useable but you do need to do a little RMS smoothing and interpreting.

Wow, the GM OEM sensors must be the best narrow-band sensor ever created.

Every single OEM O2 sensor I've encountered is designed to work best right around stoich (14.7:1). They are used for emissions purposes only and typically ignored at WOT b/c they are not accurate very far above and below stoich.

Unless you can figure out that at .xx volts you have a XX.XX:1 A/F ratio, I think you roll the dice in a big way. And add to this that once you replace the sensors, you will need to redo this little excercise.

Even then, I believe that at .85v, for instance, you could be at 13.0:1 or 10.0:1.

Depending on how radical you get, a $1k wide-band sensor isn't that expensive. I bought one a few years ago before these things got extremely popular at dyno facilities. Worth every dime...but then again, I have some serious $$ (for me) in my motor, too. ;)

If you do not want to spend that (and I completely understand...I will not put one in my Z), then you may very well want to test your car on the dyno under duress (read: high-end of normal scale as far as engine temps and ambient temps). Even then, if you tune the car conservatively on the dyno with a wide-band you should be fine. Having a wide-band on-board won't help compensate for a lame tank of gas. If you want to get more aggressive with the tune at the track, then run some 100+ octane unleaded and don't worry about it. :D

Good luck,
 

·
Registered
Joined
·
803 Posts
I reviewed the data from an OEM O2 sensor installation. Using EGT readings and plug readings, the best power O2 reading was 895 mV for that sensor. I didn't care what the A/F ratio was - just what produced the best power.
 

·
Registered
Joined
·
803 Posts
Going back to your original question, I would tune the MAFT on the dyno for max power then richen it a click for safety. If you change anything, including fuel, repeat the dyno process. The MAF should compensate for air density changes.
 
1 - 5 of 5 Posts
Top