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IO-320 Leaning problem

I’m wondering if someone had similar problem.
Trying to reach PEAK


Flight ROP:


My IO-320-D1B is running generally good when I fly 65-75% ~ 100*F ROP but anytime I try to go for peak (at 65% or less) some of cylinder are peaking higher and higher when two other cylinders quits because lack of fuel.
There is also problem with idling – under 1000rpm is rought – I tried many times with idlex mixture adjustment.

What I did:
- overhauled intake system (cracks, repaint, new gaskets, tubes)
- all spark plugs new and regapped
- magnetos checked and 500hrs performed
- replaced standard injectors to GAMI’s
- compression’s checked – 74-75PSI

Still problem like on movie. Engine run rought as I’m trying to approach even first peak…
It’s no way of course to go LOP. 100F ROP is flying fine.

EDLH, Germany

GAMIjectors are numbered, are they in the proper cylinder, you cannot mix them.

EBKT

Yes it could be GAMIs in the wrong holes. I once had an engine come back from some work and the injectors were put back randomly.

Normally, GAMIs give you concurrent peak in all cylinders on the first attempt. Sometimes you need a second iteration, on 1 cylinder, and IME the guy sends you a replacement injector free of charge.

That said, I see one of the EGTs dropping completely. This is not supposed to happen until you are way into LOP territory. If the plugs are good then I would suspect the ignition harness.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

in the wrong holes. I once had an engine come back from some work and the injectors were put back randomly.

Normally, GAMIs give you concurrent peak in all cylinders on the first attempt. Sometimes you need a second iteration, on 1 cylinder, and IME the guy sends you a replacem

I had same problem on standard injectors, GAMI’s of course I installed in proper cylinders. Regarding iteration of tuning – it shouldn’t be soo bad.
Ignition Harness look’s like new and I tested it before, nothing here..

Last Edited by Przemek at 15 Nov 09:49
EDLH, Germany

At what total fuel flow is the engine going rough?

Administrator
Shoreham EGKA, United Kingdom

I think under 20lph on this movie but I have re-check it. It was tested on low power, around 55%.

EDLH, Germany

You should also check the internal resistance of the spark plugs. If over 5K replace them.

EBKT

All new. Problem was same on old ones.

EDLH, Germany

It happened to me.
Bad sparkplugs ( high resistance) caused damage to the ignition harness (shorting). Replaced leads, same problem after a few hours. Fixed when harness and sparkplugs were changed. Bad sparkplugs tested OK on the tester but failed the resistance test.
When LOP, more spark energy is needed, fuel-air mixture is harder to ignite.

EBKT

I noticed that you lose EGT on nr 2 and nr4 pretty much at the same time while 1 &3 continue to rise. I doubt this issue is fuel or ignition related since you have the entire left bank effected by it. So the only thing that comes to my mind that would cause you lose the entire left cylinder bank at LOP is some induction leak downstream.
Induction leak can cause additional unmetered air to rush into the system, basically running an entire bank of cylinders much leaner than they should be and that when LOP, would basically cause the cylinders to flame out.

Where you at partial throttle or full throttle when you filmed this?

Switzerland
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