Using the MAP sensor

[John Appel]

I am using the Link G4 Storm on my parallel twin cylinder motorcycle engine. Engine is 1200cc with 360 degree crankshaft to give evenly spaced firing intervals. I have one throttle body per cylinder. I am currently using only revs and throttle position for inputs. I would think that at small throttle openings just off idle there would be a big change in air flow for a small increase in throttle angle so that throttle angle alone would not give a very accurate measure of airflow. Can I use input from a MAP sensor as well as TPS so that MAP would be the main measure of airflow at small throttle openings and TPS would be the main measure at high throttle openings. Can I simply plug in the vacuum hose coming from the Link to one inlet port. This would give a very pulsating vacuum signal. Should I cross connect the hose to both ports, this would even out the signal somewhat. Or should I use some form of electrical sensor. What is the usual arrangement on a 4 cylinder engine with separate throttle bodies on each cylinder.

 Regards, John Appel

[Adamw]

Hi John,

Although you can connect a MAP sensor and the ECU can use it in multiple ways, you wouldnt normally gain much by connecting a MAP sensor to an ITB engine.  If you wanted to try a MAP sensor then your thinking is correct - you would have to take a vacuum line from each intake runner into a small "manifold" and you would probably want some sort of mechanical dampening (orifice) to smooth the signal into something that is usable.

Having said that, you can usually get a reasonable tune over all operating conditions just using TP.  When using TP as your main load axis you need to set up the breakpoints on the table axis to have very small increments at small openings, gradually going to bigger steps at larger throttle openings.  Something like 0%, 2%, 4, 6, 8, 10, 15, 20, 25, 35, 45, 60, 80, 100% is what I normally do.  Is your table set up this way?