Hi Fordy,
I've been told by a few not to Tee off the MAP hose, whats the consensus?
@DaveL485 @Clarkey @Fordy @Brigsy
I use dedicated lines for everything. I think the only thing I tee off from is the feed from above the throttle for wastegate & plenum boost (the manifold boost gauge is separate). The FPR, MAP, Dump Valve, Crankcase breather, and manifold boost all have independent feeds from the main body of the manifold before the runners.
IMO the MAP sensor needs a clean reading, and it needs to react as quickly as possible which makes setting up transient throttle a lot easier and it gives a better response when you don't trip into the realms of transient throttle too. A boost gauge plumbed into the MAP line increases the reaction time. (
Following is plagiarised from Andy Wyatt 
) The ECU already has to do filtering on the MAP sensor signal to get a smooth enough signal to use for tuning purposes and filtering slows down the response of the sensor. So when you snap open the throttle, the MAP reading that the ECU sees doesn’t change straight away. However the air demand of the engine does change straight away, because the pressure wave travelling through the throttle to the intake ports moves at the speed of sound, so the engine had better get that extra fuel straight away.
To pick some numbers out of the air, an engine might idle at around 33 kPa. When you snap open the throttle from idle, the manifold pressure will go pretty much to 100 kPa in a matter of milliseconds, but the MAP sensor reading will slowly go up to 100 kPa over a period of a few hundreds of milliseconds. If you were trying to get the correct amount of fuel into the engine by providing an enrichment, then you’d need to enrich by about 200% to get the correct fuel for 100 kPa in when the ECU is still seeing 33 kPa from the sensor. We don’t like to do this because it’s a kludge; it doesn’t really represent what’s happening on the engine and working out that percentage for different throttle openings and RPM would be a big task.
So the way we do it instead is with a technique we call “MAP prediction”. It’s really simple. When the ECU sees a quick throttle movement, the ECU looks at the predicted MAP table instead of the MAP sensor, for a fixed duration. Once that duration is up, it goes back to looking at the value from the MAP sensor. During this time, the ECU actually picks whichever is greater out of the two (the MAP sensor and the predicted MAP value) so that if you’re on boost and nail the throttle the last few percent, the ECU won’t reduce the amount of fuel.
The little 5 is testing my patience. I can't get my head around what is happening despite my best (inexperienced) efforts.
