Tranlator settings

[VIN7]

Hey Turbobob,

I had set the +3200rpm fuel to -4%, and I noticed while driving the car in cold <38* weather I was getting some part throttle (interstate driving so +3200 rpm) and wot throttle knock. Now this is the same settings (pump gas and alky) where I had it tuned for 0 knock in >50* weather.

The question is, is -4% fuel the same as inj duty cycle 85% - 4% = 81%? Or is it not quite that exteme? I have put the car in storage for the winter, but I need some tuning points to ponder over the winter months ;)

Thanks,

Mike

[mgmshar]

The Translator Plus does not add or subtract directly from the %DC on the injectors. Also remember that the ECM also does not calculate %DC for the injectors. Whenever something is showing you %DC for the injectors (DirectScan, Scanmaster, whatever), it is calculated by that device, not the ECM.

Here is how that works: the Translator Plus receives an air flow signal from the MAF and a spark signal from the ECM (in layman's terms). The T+ can "tell" what the engine RPM is from the spark signal. Normally, the T+ just "translates" (thus the name) the signal from the 3" MAF sensor (or whatever you are running) to a comparable signal that would be generated by a stock MAF. It then sends that translated signal down the wires to the ECM. The ECM then multiples that MAF signal by the engine RPM, some conversion constants, and a bunch of correction factors that are stored in tables in the PROM chip to obtain the injector pulse width in milliseconds. The ECM then turns on each injector sequentially for that amount of time as the crankshaft moves through it's firing order. The ECM never calculates %DC - if the calculated injector pulse width is longer than the time between intake strokes, then the injector just stays on all the time.

If you set the T+ knob to 4% lean over 3,200rpm, then the T+ "fools" the ECM. When the T+ senses that engine rpm is over 3,200 (via the spark signal), then it "adjusts" the air flow reading that it delivers to the ECM by 4%. In other words, it lowers the MAF reading that it delivers to the ECM by 4% below the true value. The ECM then calculates the fuel injector pulse width based on the 4% lower MAF value. So, the delivered fuel injector pulse width (in milli-seconds) will be 4% lower.

I know that's probably more than you wanted to know, but hopefully this will help.