Below is an old post from Al G about restricting the MAP pickups.

Al, and others who may done this: Did you put the vacuum restriction closest to intake and then in series the accumulator closest to EC2/3?

The accumulator volume goes between the manifold and the restriction – think of it as a sort of ‘spring’ that can push and pull against the restriction without affecting things on the other side.

Did this require any more fine tuning of your MAP table?

I guess so – I retuned so many times after putting that in as I was having table corruption problems.

Al

Or has MAP restriction/dampening become unnecessary due to latest EC2 SW with low-RPM/high-MAP split in the EC2 table?

Any comments?

Jeff

John;

 That’s essentially what I did, except I used epoxy instead of solder, and used a .050 wire to form the orifice. Then used a fuel filter as an accumulator.  It improved the idle of the engine. 

 I had also found that using the un-damped MAP signal for the pressure-referenced fuel pressure regulator caused rapid pulsations in the fuel pressure.  I don’t know that this affected engine operation in any way, but decided it could an unknown stressing factor on the fuel system.  Using the damped MAP signal eliminated that phenomenon.

 All of this is influenced by the location of the MAP measuring ports.  Mine is picked up relatively close to the ports (about 6”) and would likely have stronger pulse than if picked up in an air box at the far end of long runners.

 Al G.