what are symptoms of dirty injectors?

[alaskan9974]

I noticed at cruising altitude above 8k feet or so on my io520 it would randomly shudder for a split second, like a jug was dropping out, or it ate a slug of water. It has a surefly mag so I thought it sounded like the symptoms they described when it resets.

Happened again while running just on the stock bendix mag, noticed it was aggravated when lop. Was very intermittent and never at TO power, and nothing apparent on ground runs with everything checking out fine. Finally got my mechanic in the plane, and it happened, he thought it might be the fuel servo needing adjustment. We pulled the injectors and soaked them for a bit, and then tried it out. Seems to have cleared up and I can run a bit leaner on the mixture again.

Does that sound like something dirty injectors or screens could cause? It is very annoying how intermittent it was, and was hard to describe. Was unnerving when it did happen, even though we have found nothing to point to it seems to have gone away, knock on wood.

 

[Bill Watson]

My first thought is, “I don’t know but I’m going to clean my injectors”.

Seriously, when running LOP, or more specifically when doing test runs while injector tuning for LOP, that sounds like what happens when one injector is way too small.

Doesn’t happen on TO or anytime your running ROP. But instead it happens when you get near being too LOP. Instead of a bit of roughness as the power drops off, the cylinder with the way too small orfice starts to miss fire while all the other cylinders are firing away.

So I’m thinking yes, that could be from a dirty injector. But I’m just an amateur that went through the tuning process with my RV10/IO540.


Sent from my iPad using Tapatalk Pro

 

[Jeff767]

I would not attempt to run LOP on just one mag unless you meant the Surefly was replaced with the Bendix. As mentioned in Bill’s post roughness while leaning is generally your leanest cylinder reaching the point it won’t ignite. A partially clogged injector will cause that to happen sooner. If you have full engine monitoring however you will see the higher than normal EGT on a cylinder with a clogged injector in almost all flight modes until you lean past peak.

 

[donjohnston]

When I've had dirty/clogged injectors, I found them after start up. Engine would run rough. Sometimes really rough. Not an bad at higher RPM. I don't think I've ever had the issue in cruise.