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Hi! I'm really new to all of this, so this may be a stupid question. After finishing the EFI Fundamentals course and with the little knowledge I had before, I'm a bit confused about tuning an ITB setup. From what I've heard and read on the forum(s), it's tricky to tune because it's best to use a mix of MAP and TPS signals for a reliable tune (with good AFR on both idle & cruise and wide open throttle). The MAP is really not great though because it's a N/A engine setup, and TPS is not really accurate while in idle and cruise. Here comes my question: why can't we just use a MAF sensor? I know they can be quite inaccurate sometimes, but could it work with a high quality MAF sensor that is reasonably accurate? Maybe it creates some problems like designing a custom air intake and optimal sensor placement? These could be valid problems but I feel like they also could be sorted out. So, why I don't hear about anyone using a MAF sensor or a combination of a MAF and TPS sensors to control an ITB setup?
I'm currently designing this kind of setup for a 1.3l CG13DE engine with a standalone ECU and a custom wiring loom, upgraded injectors, ported cylinder head, potentially more aggressive/bigger cams and ignition coils instead of the distributor. It would be a shame if it couldn't be tuned effectively and relatively easily because of the problems with measuring the air flow to the engine. Can anyone help me figure this out?
Generally in aftermarket applications people will use a combination of a RPM x TPS and multiplied by a MAP x RPM table to capture both if they aren't happy with one or the other. Introducing a mass flow meter can bring other measurement problems such as controlling airflow distribution in the pipe and controlling intake resonance, just throwing an AFM in line doesn't guarantee you can tune it perfectly to the nominal calibration scale of the AFM without any complications either.
Reality is, naturally aspirated, if the throttles are balanced alpha-N should be fine. You could introduce barometric compensation if you will be changing elevation significantly or go to a full multiplied or blended strategy if you are keen.
Thanks! So just to be clear, it could be easier to use MAP and TPS? And quick question, what's "alpha-N"?
Alpha-N is another term used for throttle angle vs engine speed map.
If you look up a few common aftermarket ecus you should be able to see how they implement the combined load tables.