I have been messing with my Tunercat and reading a lot of stuff on programming the PCM, I read that some tuners use the injector size to fiddle with the AFR. I have always run a little rich so I increased the size of the injector (as far as the computer thought) which should have the computer throw more air into the equation, makes sense. :!: So now it reads that my injectors are 26.35lb/hr, and I’ve run a LOT test runs under the same conditions today, :? Where'd the knock go? I was consistently having 4+ deg of timing pulled above 4000rpms, now none, and as far as my O2's are concerned everything is cool.

Does this make sense to anyone, I pretty much leaned it out more and knock disappeared :? I thought that knock was normally made worse but leaning it out, or was I just so rich that it knocked that way also?

 

does anyone know how this worked? or have any explanations. also wondering if this will fix the problem with others who complain about knock above 4000rpms?

 

I doubt you changed anything as far as A/F ratio. Increasing the injector constant artificially means your PCM is adding too little fuel for the air measured by the MAF sensor. In closed loop, the O2 sensors pick up the shortage of fuel and increase the pulsewidths back to where they were originally, building the long term fuel corrections above 128. When you go into enrichment mode at WOT, the PCM is going to use the same "add fuel" long terms it was using in closed loop..... net difference = zero.

You alter A/F ratio with the PE tables, not by faking the injector constants. Your P&P MAF is possbily contribuiting to the knock problem because you've altered the calibration. Have you attempted to recalibrate using the table?

Can't explain why what you did eliminated knock, but if it worked, leave it alone. You may just have two errors canceling each other out at this point.

 

Thanks for the info, I just found that the PE tables in tunercat are the ones about;
%change to Fuel/Air Ratio vs coolant temp @ WOT
%change to Fuel/Air Ratio vs RPM @ WOT

As far as ajusting the calibration of the MAF, I don't know where to start
So I will look into those, again thanks for the help