Managing throttle tip-in with ITBs

[Craig Richmond]

Hello! I am about to start tuning a new engine running on a G4+ Storm. This is my first time with Link, and I have some questions around dealing with throttle tip-in with ITBs. The standalone systems I've used in the past supported some blended MAP and  Alpha-N maps to help optimize tuning with multiple throttles, and I curious to see how PC Link handles this.  ITBs are notoriously difficult to get decent part throttle and tip-in performance working properly, so I thought I'd check in here first to see if anyone had any advice to share. Thanks for your time! 

Engine specs: 

2.0L 16V 4 cylinder, naturally aspirated. 

276 cams

11.5:1 compression

42MM throttle bodies

Sequential injection & coil-on-plug

MAP sensor fed from a vacuum manifold off of each throttle

[Adamw]

I have done quite a few NA/ITB race engines and always use TPS only for the load.  I cant see even a well 'dampened' vacuum manifold giving you a useful signal for a MAP or blended load.  The blended MAP/TPS strategies are useful for boosted engines with ITB's but not needed in your case.

I connect the MAP sensor to the airbox only to compensate for any aerodynamic pressurisation. 

I have never had any issues with transient response with this type of setup.  One thing I will mention is that with TPS based load you must setup your load axis with fine increments/resolution at low TP.  So I normally my load axis would be something like:

0%, 2% 5% 7% 10% 15% 25% 40% 60% 80% 100%

Then after initial tuning if there were any big changes in two adjacent rows then I might insert another load row.  

[Craig Richmond]

Adam, thanks so much for responding!  The load axis you propose certainly makes very good sense with ITBs as they are so often effectively wide open by 40%.