MSefi.com read only forum (Jan.15,2018)

Okay, I seem to recall way back when that one might need to restrict the tubing for the MAP if they started to experience a problem.
I don't recall the details around that.

What is happening with me, is at higher RPMs, my MAP reading is pulsing quite heavily.
I lowered my MAP sample rate and I set my acceleration to be 100% TPS (MAP was causing constant accel decel).

MSII 2.886 on a 2.5L 4 cyl with single TB and MultiPort injection. MAP tube attached midway down one of the runners on the intake manifold.
(Maybe I need to simply move this to the TB?)

Should I just keep lowering the sample rate? Was there something to the restriction of the MAP tube?

Thanks!!!
-Nick

Nick, I think you have it right. Move the MAP sense point to a central point that is larger in volume and common to each cylinder, if you have that option. I'd avoid anywhere near the throttle body if I could.

Oops, wrong tubes (Vac gauge and MAP have the same hoses). Maybe that is the problem. My MAP connects just below the TB. I have about 6 ports just below the TB and only 1 midway down the runner. I'll try swapping the vac gauge and the MAP. Thanks!

P.S. Anyone recall adding a restriction to the MAP tube? Or is my memory failing me? I might have some old instructions that I had printed out when I built my MSII, but I was under the impression that at one time they might have suggested adding a restriction (possibly to prevent the problem I was having)...

MB_Custom wrote:P.S. Anyone recall adding a restriction to the MAP tube? Or is my memory failing me? I might have some old instructions that I had printed out when I built my MSII, but I was under the impression that at one time they might have suggested adding a restriction (possibly to prevent the problem I was having)...

MegaScott wrote:You have your map hose from the throttle bodies, then in the end of the hose you put an 0.030 or smaller MIG tip, then a Briggs&Stratton fuel filter to your MAP sensor. The MiG tip slows down the signal through the filter which acts like a reservoir to smooth out the Map pulses some.

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