Van's Air Force
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High EGT one cylinder
- Thread starter Jake14
- Start date
Mag check on ground at 1800 rpm or in flight at the 2600 rpm? I had similar issue and the bad plug only showed bad on mag check at cruise rpm. See post 16
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Cause for one cylinder to suddenly increase EGT over several flights
I have an IO-360B2B with a Bendix RSA-5AD1 servo with a SDS SDI ignition on the upper plugs and Slick traditional mag firing bottom plugs. I just completed my condition inspection (CI) in December where I had replaced the upper NGK BR8ES solid 3961 plugs, cleaned and re-gapped the lower plugs...
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The CHTs on your graph look good and pretty consistent, not high enough to cause alarm. But since it's a change from the past could mean something. What kind of fuel injection do you have? Have you done a GAMI lean test to see if all cylinders are peaking near the same fuel flow? Since you say this happened on takeoff it could mean that cylinder is a bit lean compared to others: if it's a new issue perhaps the injector on that cylinder needs to be check for a bit of trash etc.
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RV10inOz
Well Known Member
You have a partial blockage in the line or injector to #3. This is classic APS class stuff.
Why?
1. You have a noticeably higher EGT when full rich. If you went LOP it would run rough.
2. You have elevated CHT (assume this is unusual also) so it confirms a less rich mixture along with elevated EGT. Note this is not a lean mixture, just a less rich or not rich enough.
3. If it was a plug that was faulty or fouled, you would have an elevated EGT but nowhere near that much. And the CHT would be much cooler than normal. A fouled or faulty plug/lead usually gives about a 80dF rise. Just like doing a mag check.
Carefully clean the injector and line. There may be a small chance of a bit of junk in the fuel divider, but most likely in the injector.
Why?
1. You have a noticeably higher EGT when full rich. If you went LOP it would run rough.
2. You have elevated CHT (assume this is unusual also) so it confirms a less rich mixture along with elevated EGT. Note this is not a lean mixture, just a less rich or not rich enough.
3. If it was a plug that was faulty or fouled, you would have an elevated EGT but nowhere near that much. And the CHT would be much cooler than normal. A fouled or faulty plug/lead usually gives about a 80dF rise. Just like doing a mag check.
Carefully clean the injector and line. There may be a small chance of a bit of junk in the fuel divider, but most likely in the injector.
My son fought one of these for 2 months. Cleaned injectors and lines, replace intake gaskets and coupling. Wound up being the flow divider.
RV10inOz
Well Known Member
Yeah that can happen. Usually a bit on gunk in there, or was it a faulty unit? Not much to be faulty as they are very simple but never say never.
FabricGATOR
Member
Lean fuel injector or intake leak. (or both)
I seem to remember a procedure I think it was an AD on turbocharger exhaust but it could work here. Use some plastic bag or even rubber innertube *with the valve stem and the idea is to use tywraps, tape, or even jubilee clamps to seal off the intake, the exhaust and also the crankcase vent (s). Then, using shop air and a pressure regulator apply a little air pressure (as little as will be revealing) then search for leaks using soapy water in a spray mist bottle.
I seem to remember a procedure I think it was an AD on turbocharger exhaust but it could work here. Use some plastic bag or even rubber innertube *with the valve stem and the idea is to use tywraps, tape, or even jubilee clamps to seal off the intake, the exhaust and also the crankcase vent (s). Then, using shop air and a pressure regulator apply a little air pressure (as little as will be revealing) then search for leaks using soapy water in a spray mist bottle.
David,
He did not open it up so not sure what was in there.
