Re-balancing GAMI injectors?

[AA5Bman]

Hi everyone, I’m a big fan of LOP operations on my IO-470S and I’m hoping you will assist me in not making this a LOP/ROP argument (and help me with balancing the injectors!).

I have GAMI injectors and typically run 7,000-11,000’ MSL, 21” MP or as much as I can get, 2300 RPM, and 11ish gallons per hour, which usually results in about 40 degrees LOP.

I can’t tell if I’m just being paranoid or noticing more, but lately I feel like I can’t get quite as deeply LOP before the engine startles to run just a tiny little bit rough, and maybe my #6 cylinder is peaking later (ie running slightly richer) than it has in the past. Again, it’s hard to say if this is “real” or I’m just being paranoid.

I’m going in for annual this month, is it possible for GAMI injectors to “slip” over time, for lack of a better word, and need “re-balancing”? How hard is this to do? I’m wondering if this is something we should look into at annual, or if it is going to deserve it’s own visit to a shop - and potentially to a shop that is familiar with GAMI injectors and LOP operations.

Thanks in advance

 

[flyingron]

Has anybody been near the engine? I had a mechanic scramble my injectors. They went from all peaking within an 1/8 of the turn of the mixture control to being all over the place. We put them back in the right cylinders and all was better.

 

[brcase]

I am a total amateur at LOP operations, but from the reading I have done on it, my 1st thought was you might have a spark plug going bad. I understand good working spark plugs are a lot more critical in LOP operations than they are in ROP operation.

Although after re-reading your post. I would expect the offending cylinder to peak a bit sooner than the others. But what do I know.

Might do some reading on doing LOP run ups. It might help you identify the issue better. Or not.

Brian

 

[AA5Bman]

Has anybody been near the engine? I had a mechanic scramble my injectors. They went from all peaking within an 1/8 of the turn of the mixture control to being all over the place. We put them back in the right cylinders and all was better.

No, I don’t think that’s it. Haven’t had any engine work done other than oil changes for a while.

I am a total amateur at LOP operations, but from the reading I have done on it, my 1st thought was you might have a spark plug going bad. I understand good working spark plugs are a lot more critical in LOP operations than they are in ROP operation.

Although after re-reading your post. I would expect the offending cylinder to peak a bit sooner than the others. But what do I know.

Might do some reading on doing LOP run ups. It might help you identify the issue better. Or not.

Brian

Good ideas. I could see this being a spark plug issue - they haven’t been cleaned, gapped, or replaced for a while.

 

[GRG55]

When was the last time the injectors were removed and cleaned? If you are about to go into annual I would assume at least a year ago and XXX hours? Maybe a lot longer than that? Mine get done every annual.

There is no "re-balancing" with GAMIjectors. Each injector has a number and that is matched to a specific cylinder on your engine type. As @flyingron noted in post #2, they have to go back on the same cylinders they came off - they cannot be mixed up.

 

[Let'sgoflying!]

Do the Lean Test and see how close the peaks are.

 

[Tom-D]

Annual????
Be certain all injectors are in the correct hole.