MAF FAQ (long)

[Robin-535im]

I'm curious to learn more about DME and MAF's.

Here's my understanding: DME uses O2 and MAF readings to determine a/f ratio and air flow rate, then uses this to look up on the chip timing and fuel tables what the timing advance and fuel duration should be.

Adding a MAF tricks the DME into thinking the air flow rate is different, so it looks at a different place on the chip and chooses a different timing and fuel pulse duration, right?

Then why can't you just reprogram the chip maps to mimic the effect the MAF adjustment has?

Also - won't the O2 sensor see that the ratio is not as expected and continue to correct the mixture? I would think you'd want to tweak the MAF readings and the O2 readings too, so that the DME happily thought it was running a/f 14.0 when it was really 13.5, etc.

Also again, BillR told us once (where is he BTW?) that the reason the car has more power when cold is that the DME is not in closed-loop mode with the O2 sensor, instead it's running open loop and you're not operating at the programmed a/f ratio. Is that the same basic effect you get from a MAF, you can run the car at different a/f ratios and get some of that lovely cold-engine-power back all the time?

- Robin