42# injectors on stock computer?

Don 95Vert said:

Here's a MAJOR problem with running any larger injectors with a Pro-M calibrated for them without a chip. Pro-M calibrates a MAF by altering the circuit so the MAF sends the EEC less voltage, i.e, it fools the EEC. So, if stock you have 19# injectors and you switch to 42# injectors, the voltage at WOT that the EEC sees is about 45% of where it used to be. So for the same amopunt of air passing into the engine, it fires the injectors 45% less as opposed to stock. This same MAF data is also used by the EEC to calcuate load - and load is used by the engine (from '94 on up) to determine spark - it's also used to determine target A/F in the base fuel tables, even on earlier processors. When you look at the spark and fuel tables and see what the 45% load values are at 5000+ RPMs you'll see that rather than the timing being 25*, it is between 32 and 38* and in the fuel table the commanded A/F is about 14.1 rather than 12.2 (this is for a W4H0 EEC) - you can see, especially on a blown car, why this can be very bad.

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