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Topic-icon Lagging Manifold Pressure Gauge

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7 months 6 days ago #2234

Tell it to the guys at the airport. They will either say, "Wow, who thought that up??" or, "Nah, this is the way to do it."

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  • Warren Booth
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7 months 1 week ago #2229

Thanks for the fast response!!! That makes total sense!!! I saw rudimentary similar tactics used for a pitot/static system leak check. I’ll definitely add a long run of surgical tubing to my tool box. My wrenching experience is on big jets where one uses a machine to test another machine, no talent or skill needed....green good, red bad!!! ZERO FUN. I enjoy the brain work and head scratching with the manuals opened up.....the wife gets bored to tears when I excitedly share the “AH HA” moments!!!

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7 months 1 week ago #2228

I would create a field check of the gauge to see if there's something wrong with it. Something as simple as disconnecting the MAP connection at the engine and connecting a rubber tube over the end. Then run the tube in to the cabin so you can watch the gauge as you apply vacuum (suck) on the tube. If it lags then you know it's the gauge and that it needs to be sent back to the repair shop for cleaning or repair.
I hope you weren't expecting a more sophisticated test!

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7 months 1 week ago #2224

I have a standard combination MP/FF gauge. It’s only a year old (rebuilt unit). It worked fine up until now. The manifold pressure seems to lag throttle inputs and takes about 6-7 seconds to settle into and accurate MP reading. Once cruise power is set and leaned back to adequate CHT/EGT I’m at about 17.5 GPH. I then make my power changes based on fuel flow and wait for MP readings to settle in as a “double check” (23”). I’ve disconnected the MP line at the gauge and the engine and blew it out with shop air FROM the gauge end to the engine end. Hooked it back up....no change. Any ideas?

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