podair Posted July 30, 2011 Report Posted July 30, 2011 Looks like a JPI EDM probe might be going funny on one of my cylinders (IO360 A1A M20F) Quite sure now it is a probe issue but if anyone has another opinion: WOT 65 to 75% power at 8-10k feet on two separate flightsleaned to peakcyl 2 egt starts going haywire after 1h of flyinginitially 10-20egt spikes then frequent 100 F spikesengine humming smoothly chts rock steady and all 3 other egts tooLOP mag test smooth as well so ignition looks okeven full rich egt 2 does not steadyflying 100-200 rop seem to calm things down for 10-15min spikes soon resumesame thing switching out of normalise mode calms things down then spikes again, up to 200-300f50h check tuesday will swap probes and look and plugs too but at this point I m pretty sure its a duff probe now, i ve had huge spikes in egt without the engine missing a beat and everything else rock steadyalso why does this stuff always happen when I m either over a mountain range or miles offshore? Quote
Shadrach Posted July 30, 2011 Report Posted July 30, 2011 It's a probe...maybe a loose connection. Unless you have an STC'd blast furnace under the cowl, there's no way your CHTs are "spiking" 200-300df; if by "spiking" you mean 2 to 5 seconds. If you mean 2 to 5 minutes, well.... Quote
fantom Posted July 30, 2011 Report Posted July 30, 2011 Been there, done that. It's a loose or bad probe. Quote
M016576 Posted July 30, 2011 Report Posted July 30, 2011 Loose, bad probe, or it's grounding out somewhere. When I first bought my M20J, on my flight back to my home base, I had a loose grounding wire on the ship's instruments. The net result was that the fuel quantity indicators were "windshield wiping" back and forth, the oil temp probe was slowly rising all the way up to the pegged position while the oil pressure gauge was falling all the way toward zero. I pressed hard on the panel where the ships gauges are and the needles would all snap back to normal indications. When it first happened, my heart initially dropped into my stomach.... then I pushed on the panel and realized it was just a loose wire. Easy fix.... thankfully! Quote
jetdriven Posted July 30, 2011 Report Posted July 30, 2011 might possibly be a bad valve. it rotates and leak s on a measured interval of like 2 minutes Quote
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