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G3X Engine Monitor Manifold Pressure jumpy

flysrv10

Well Known Member
Just installed GEA24 in my IO540. The manifold pressure gauge jumps around about 1 inch, sometimes a little more at cruise, so you end up chasing the number.

Is this normal with others on the forum? Is it possible that the sender is defective?

Thank you.
 
we have the same issue with varius installations, some of them were fixed with a restrictor in the fitting, but we have one case that we are dealing with the jumpi MP and with restrictor without change.
 
Just installed GEA24 in my IO540. The manifold pressure gauge jumps around about 1 inch, sometimes a little more at cruise, so you end up chasing the number.

Is this normal with others on the forum? Is it possible that the sender is defective?

Thank you.

Yes, it's normal -- the intake valve hammering sets up pulses that the GEA 24 pressure transducer "sees" (feels ?) which results in fluctuating MAP readings.

Install the Omega Engineering PS-8G snubber as described in the installation manual -- Revision AP, Page 24-24.
 
Thank you. I will check this out.

You can get the restrictors in various sizes at Mcmaster carr. .020 to .040 seems to be a good range, though I have .004 on my 10 without a meaninfull lag in response time. I have a home made version on the 6 that works well. Take a -3 Alum line and fill with JB weld, then drill with #60 bit. Then cut line and insert. I use good old vacuum line, but this wont work if you have a braided line.

Larry
 
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You can get the restrictors in various sizes at Mcmaster carr. .020 to .040 seems to be a good range, though I have .004 on my 10 without a meaninfull lag in response time. I have a home made version on the 6 that works well. Take a -3 Alum line and fill with JB weld, then drill with #60 bit. Then cut line and insert. I use good old vacuum line, but this wont work if you have a braided line.

Larry
Thanks Larry, do u by any chance have a part number for Carr?
 
Originally I had a .04 restrictor on my RV-10, it was useless - much too big.

I changed to a .004 and it has worked great. McMaster part is 3820K26.
 
McMaster Carr part number 3820K26. I used the .004 orifice on my -10. Works great and as others mentioned lag is minimal but MP is solid.

One note: Add the removal and cleaning of the orifice to your condition inspection checklist as mine started to clog after 18 or so months and the MP would freeze or move very slowly.
 
One note: Add the removal and cleaning of the orifice to your condition inspection checklist as mine started to clog after 18 or so months and the MP would freeze or move very slowly.

^^ ^^ This ^^ ^^

Always good practice to clean your orifices :)
 
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There are other important variables besides the orifice diameter. The length of the restrictor will greatly affect the damping. Likely even more important is how much air volume there is between the restrictor and the transducer, i.e., tube diameter and length.

Also, it's probably best to not feed an electronic ignition this highly damped pressure source, as a sudden throttle increase will not be detected by the ignitions until after a delay. I have two restrictors on my setup - one for the ignitions (I don't recall if its installation manual discusses this or not) and one for the MAP gauge. As it happens, I'm a bit over-damped on the MAP, but the delay in indication is irrelevant to most operations. I had an oscillation in the MAP indication before adding this restrictor.
 
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