The Ultimate FA20 ITB thread.

[RedReplicant]

Originally Posted by blsfrs

I'd be curious to know how the ecu monitors intake air volume without a MAF or MAP. If not monitored it's almost like having multiple carburetors.

You don't, you map against TPS rather than MAP and you have correction table for altitude adjustment. An ITB car is complicated to tune, you'll find that OEM manufs with ITB vehicles also have a MAF or do MAP at idle/low rpm and change over to TPS at a certain point. This is how BMW did the S54.

Most aftermarket setups are crippled in some way.

[NoHaveMSG]

Originally Posted by RedReplicant

You don't, you map against TPS rather than MAP and you have correction table for altitude adjustment. An ITB car is complicated to tune, you'll find that OEM manufs with ITB vehicles also have a MAF or do MAP at idle/low rpm and change over to TPS at a certain point. This is how BMW did the S54.

Most aftermarket setups are crippled in some way.

Pretty similar to how early dirtbikes/atv's where when they went to fuel injection. Correlated TPS with RPM and used O2 sensor for correction. Or something like that, it's been something like 15 years since I played with any of that.