I honestly dont think that going to a colder plug will help your situation as far as fixing your a/f. And dont even think about running N20 until you get your engine running good a/f's first....try going to another dyno just for $hit and giggles and see what kind of numbers and a/f reading's it pulls.

 

My recommendation is to get a piggy-back or standalone module and pay for a couple hours and get it tuned to what you want.

 

Has anyone thought what the greatest single individual loss item is in using a chassis dyno: clutch, tranny in direct gear, drive shaft, diff, half shaft, wheel bearings, wheels, tires, alignment under acceleration [rear thrust angle]? Hint the rear diff doesn't exceed 3.4% above 25 mph.

 

How can a A/F ratio meter be accurate when stuffed in a tail pipe [with a series of cats reacting the excess fuel in front........always shows significant lean errors unless ACCURATE Wide Band is bunged in to headers before first cat!

For about 75 years engines generally have produced the highest peak torque with 12.5AF [+-0.25] and peak HP with 12.2AF [+- 0.25] as measured close to exhaust port.

Nissan typically uses a REAL WOT AF of 10-11.5 A/F at high rpms.

 

if you ever log a wideband pre cat vs the sniffer in the tailpipe, you would be amazed at how close they can be if they are both in good operating condition.

 

Very true. This is my car using a precat sensor:



Its hard to read but there is a faint yellow diagonal line across the chart which shows the RPMs. The A/F ranged from 13.5 to 12.5 approaching 6000 RPM.

This is my car using a tailpipe sniffer done the very next day on another dyno:



Almost the same, with some variance around 6000RPM but I am guessing that around the time the foot was let off the gas.

If the machines are calibrated and operating properly, they should be reasonably accurate.