Paul K

Paul K

Well Known Member
I did my first engine run today and all is well except my MAP readings.

I have a dual GRT HX system with the EIS. I am using the remote MAP sensor.

Before I start the engine, I am showing about 13 inches. After start I am showing about 3 to 4 inches. I would expect the MAP to mirror the baro before start but it seams to be subtracting inches instead of adding inches!

I've checked all the plumbing and the wires are all solid. The question is, can it be as simple as wired backwards? My GRT manuals are at the airport so I can't look anything up. GRT is closed and there isn't anything that I can put my finger on in the WEB files.

Any ideas?
 
Engine off it should read actual barometric pressure, e.g., about 29.92" minus an inch per thousand feet you are above sea level.
After engine start, at idle, about 15" as the engine is sucking a vacuum in the intake manifold.

Sounds broken.
 
Bob,

I think I'll pick up the installation manuals with all my notes and sketches from the hangar tomorrow so I can remember how I installed it. It's been a few years!

I don't recall being able to change any settings or numbers in the MAP section. I hope that's all it is!

Finally, if all else fails, a call to GRT Monday......
 
I'd bet on the scale factor ...

IIRC, the GRT MP transducer has an info sheet that specifies the correct scale factor for the device. Make sure you have that input correctly. I set up my GRT using that info and it's spot-on.
 
It would appear that I missed the bold faced, hi-lighted, boxed note on setting the scale factor! :eek:

Makes me wonder what else I missed! I think this calls for a stand down, to evaluate and check the entire system.

Thanks Bob and Rupester,
 
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