Vacuum Rail Project

 

My engine is not an easy one for the ECU. 292 intake cam, individual 50mm throttle bodies with functional ICV is a very difficult setup combined with 14.7 target AFR at idle.  Load detection is TPS/MAP, Patented by Richard Aubert (Autronic creator). See the patent here: http://www.freepatentsonline.com/6405715.html

Due to large cams and separate intake runners, MAP signal becomes problematic as seen in the picture below. In this picture, MAP is taken from intake using typical setup with lines from each runner going straight to the MAP sensor.  Large variation can be seen in the signal.


To fix this issue, I made a vacuum rail as shown in the picture below. It uses the OEM vacuum tuning ports, each port is connected to the rail and has one output to ECU. Here’s a new trace with the rail, vacuum is much more stable.
Also, note the Intake Air Temperature sensor on the Cyl1 intake runner.



Here's how the vacuum signal looks now:

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