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Al, been there, doing that with the RC thing - .04"/1mm and a cheap

generic plastic fuel filter work very well at all RPM and load ranges. I

can send you some datalogs if you wish. If the orifice is too small, the

ECU has to wait a few tenths of a second for an accurate MAP signal.

This causes a short period of enleanment and a momentary stumble. It's

actually the flow in and out of the capacitance that you're restricting,

not the extremely miniscule flow that the sensor diaphragm generates, if

any. I think most MAP sensors are strain gauges. You want

Manifold->R->C->MAP sensor as your sequence of parts. I've spent many

hours getting this right by trial and error and have extremely smooth

sensor response even at .01 second data logging intervals at 800 rpm idle.

 

-Mike

 

Can’t argue with success.  Yes, you would not want a very small restrictor upstream from the accumulator.  My logic was telling me that the most effective pulse dampening with the least effect on response time would be a smaller restrictor on the controller side.  But logic doesn’t always match reality, and I suppose that option was one of your trials.

 

What application and ECU are you using?  Do you suppose it is independent of those things?

 

Al