Arrow II Engine Problems

flyinskwurl

Lyc. IO-360-CIC starts normaly and runs perfectly for about 60 seconds then begins to miss badly. This keeps up for 45 seconds or so and then clears up. the engine runs fine afterwards for as long as you want to run it (on the ground or flight) Problem does not happen again until it has set over night and the first start up of the day is the same thing all over again.
Leaning does not clear it and the miss does not follow either mag. The plane has been grounded since September because of this and it has been in shops several times and no one has been able to fix it yet.
Anyone ever heard of this?
You may reply to me at flyinskwurl@aol.com (flyinskwurl(at)aol.com

flyguydon

This sounds like the fuel servo. Next time, look at the fuel flow indicator and see if it jumps around during this rough running episode. Is this problem reliable... meaning it always does it... or does it only do it sometimes? Does it do it at any power level?

Where are you based? I would be curious to see the problem. Has any other A&P taken a good look into it?

flyinskwurl

Thanks for your reply.
At the start of this problem it happened at every start up. Sometimes now it will start and just have an almost undetectable miss. None the less it is still missing.
At the times when it really misses bad.. advancing the throttle makes the miss worse and the engine backfires.
My A&P has consulted with other mechanics. The last time I talked to him he was leaning towards a fuel problem.
I am located in the Piedmont area of NC.

flyguydon

A non ignition (not a mag or plug) miss that increases with advancing the throttle is sounding a lot like a "lean miss". The fuel servo has a system in it that considers the manifold pressure and altitude and compensates/adjusts the mixture based on that. If it sticks at or near the idle setting for some reason and then later begins working, you may have some varnish or something in that part of the system.

Try this. Go make it happen. Leave it at a power setting that is missing (but not so bad you can't stand it) and just leave it there. If after a minute or so it starts being normal "all at once" like you flipped a switch and now it is all better... I'd bet you it is the fuel servo. If it is doing it and you can go to full power without it seeming like the end of the world... that will likely make it correct itself quicker via the higher manifold pressure.

Does this or has this plane sat for extended periods of time? How long (calendar time and/or operating hours) since the servo was OH?

To OH the fuel servo will cost about $1000 plus whatever whoever installs it will charge you. There are other things you can try. Let me know if you want to discuss them.

flyinskwurl

Thanks again for the reply.
Yes the plane has set for a couple of long periods mostly durring winter time for maybe 2 to 3 months and once a couple of years ago because of a medical issue. However when this problem started the plane was being flown weekly and had been for about 4 or 5 months.
If you have any more suggestions I would like to hear them. I'm open to any help you can offer.
The engine has less than 200 hours SMOH. But that is over 5 years.

JoeB

flyinskwurl wrote:

Lyc. IO-360-CIC starts normaly and runs perfectly for about 60 seconds then begins to miss badly. This keeps up for 45 seconds or so and then clears up. the engine runs fine afterwards for as long as you want to run it (on the ground or flight) Problem does not happen again until it has set over night and the first start up of the day is the same thing all over again.

An engine which runs rough on startup but then clears up can be a sign of a sticking valve. It's called "morning sickness" and is a classic symptom. After the engine starts to warm the valve unsticks and the engine runs normally. Good to catch this before the valve decides to stay stuck. More here:

http://www.sacskyranch.com/eng176.htm

I'm not saying that *is* what you have - but you definitely want your A&P to consider it and rule it in or out.

flyinskwurl

Thanks JoeB
The sticking valve thing was our first consideration. All the clearances are good and a look inside doesn't show any signs of valve trouble.
That was my first thought too before taking it to the Dr.

flyguydon

Yeah on the valves, but they do not usually run fine for a minute and then act up... they usually act up from the start and then may clear up later.

flyinskwurl

I talked with the shop this morning to see how the gremlin hunt was going. He is convinced that there is fuel contamination. Not water hanging out in the tanks or the gascolator that I would see on preflight but within the distribution system..(including the RSA)
Ignition and valve problems being ruled out the fuel system is the likely problem.
The bad missing and backfiring seems to have stopped and is now only a slight but noticable shudder and weak missing at the time the original problem was happening..but only lasting for a much shorter period. (about 10 seconds)((but still not fixed))
Hopefully because the lines, injectors and associated parts have been removed and cleaned and checked the original problem has lessened and we are on the road to finding the problem. I haven't ruled out the RSA as the problem but I would like to make sure it isn't something else before sending the thing off for a $1200 check up.
I'm still open to suggestions.

flyguydon

Certainly not approved, but if you put 2 cans of high quality carb and choke or fuel injection cleaner ( be certain it is not one of the ones that have methanol as that stuff eats every gasket, etc up...) into each of your tanks... and then disconnect the injector lines at the injector. Run hoses from the injector lines into a gas can or something. Run that mix through the system (go full rich and full throttle) on the electric fuel pump a few times.

Perhaps your problem goes away.

flyinskwurl

I'm not hearing from the shop so I can only guess that they aren't finding anything or they are just not working on my plane.
If I decide to use your suggestion of using the carb and choke or injector cleaner..I assume you mean to drain the fuel out of the tanks and run the "snake oil" through a couple of times....Right?
I am to the point of trying anything within reason but I don't want to cause myself more problems in the process. Your suggestion sounds reasonable to me..but the A&I won't do it. I'll have to.
Thanks...E

flyguydon

I dunno. I am an A&P and I'd do it. Get one tank at about 1/2 full. Put 2 cans of good stuff... make certain it has no METHANOL in it... in that tank. Out on top of your cylinders you will see the 1/8" lines going to your injectors. Disconnect them and put a hose on each one and have them go to a gas can.

On battery power run the electric pump. Go full rich and full throttle. It will probably do about a 3rd to a half a gallon per minute back to your gas cans. If you can strain that gas... pour it back in the tank and run it again. Do it like 3 times. Go ahead an put the fuel back into the tank.

Hook it all back up. You really need to be careful about the injector lines as they can crack or twist if you are not careful... and certainly get a wrench on the injector (7/16") base so it does not spin when tightening on the lines...

Switch back to the other tank and try running it. Then... let it sit overnight and try it. May be OK.

Honestly... and there may be some folks here that think this is nuts... but once at altitude I pretty much think you are cool to switch over and run on the fuel with cleaner in it. Won't hurt a thing.

flyinskwurl

Got it.
Thanks again for your help and suggestions. I did pass along the info to my guy. He didn't do the cleaner mix because he claims that since he took the system apart and cleaned the componants the problem has cleared up. 10 or so starts from cold with no problem. I got the plane back this afternoon and will be going by the airport first thing in the morning for a while to crank it and see if it has cleared up.
I will be doing the annual in April and I think I'll try the cleaner if it starts to act up again.
Thanks again for your help and to the folks that replied via e-mail.

flyguydon

If they took the RSA servo apart, you are supposed to flow test them on a bench before using. If they did not take the servo apart, your problem will likely continue. Be careful.