Fuel to Air ratio - BMW Forum

robbins6103 · 07-09-2004, 01:01 PM

I just bought a Dinan CAI and throttle body for my 328, someone told me that I would have to change out computer or have it reprogrammed to correct for the fuel to air ratio now that there is more air running to the engine. Is this true?? Does my current stock ECU recognize this? I'll keep researching in the mean time.

Bear · 07-09-2004, 01:12 PM

The computer shopuld recognize this and compensate. I have a relfashed ECU and a CAI in my daily driver Neon and I never chaged a thing, runs great and fuel economy super.

Furious · 07-09-2004, 01:23 PM

you can get the ecu flashed to update and compensate, however they only recommend it to get the most out of your new mod. other than that you wont really notice a difference, i think the MAF sensor will compensate the amount of gas to induce

robbins6103 · 07-09-2004, 01:24 PM

ECU flashed? What does this mean and where would I go to do it?

Furious · 07-09-2004, 01:32 PM

flash or sharking is what aftermarket companies do to upgrade the engine. Its the equivalant of when you hear people wanting performance chips. However some companies can compensate for new mods and some dont, i suggest talking to dinan and see what they recommend

robbins6103 · 07-09-2004, 01:35 PM

Cool thanks for all the help, the Dinan specialists are right down the road...I'll run over there.

Autotechnica · 07-09-2004, 03:22 PM

The ECU will only somewhat compensate for the increase in airflow by making the fuel mixture richer. However, if you really want to tune for perfect A/F ratio, you should buy an adjustable fuel pressure regulator and some kind of gauge you can fit into the interior that would measure A/F ratio. Unless you run the car on the dyno, even Dinan won't know what the perfect A/F ratio is for your car. Every car is different right?

I have an FPR by BMP and an Autometer A/F ratio gauge. With moderate modifications tuning for perfect A/F ratio will give you some small gains. It will do wonders for a highly tuned motor. If you decide to get an AFPR, make sure it's a rising-rate one, which means you can tune for more lean or more rich rather than just more rich as most of them do.

Bry