3W70 engine problem
 

I have 3W70 that starts and runs fine, but after 5 or 6 minutes of flying it starts to miss and losses power I have tried running it rich and there's no difference, and the engine is not hot.
changed props down to a 22X8 to be sure it not over propped and same thing, made sure there is ample air flow for cooling, sent ignition module into Cactus and it came back as tested good reinstalled and flew again still the same 5 minutes and losses power.
Can the pickup sensor cause a probelm like this?
I had a problem with a Brison 2.4 that would run for 8 ot 10 minutes and then it would die like it was shut off, turned out to be the hall effect sensor, big difference is the 3W70 does not die it will keep running like crap.
Shut it off and restart it 5 minutes later and the same thing for a few minutes it will run fine and then it starts missing again.
I have email cactus so far no reply.
Has anyone heard of this happening before?

Wyldman

RE: 3W70 engine problem
 

It could be the ignition heating up or giving out. Make sure the module has plenty of cool air flow and is not flush mounted.

RE: 3W70 engine problem
 

the ignition is mounted on rubber gromets and has 1/2 inch of clearence underneather and is mounted on the side of the engine box out in the open.
It has plenty of cooling air but if it's going bad then it will get hot inside and start acting up.
I was hoping someone else has already had this happen and new the solution so I don't have to buy and ignition system if I don't need to.
thanks
Wyldman

RE: 3W70 engine problem
 

It still might be getting too warm if it is on the motor box and cowled up.

RE: 3W70 engine problem
 

If you have an in line fuel filter, it might be causing an air leak. Try removing it and see if that helps. If you have a choke on a servo, check to see if it's not going closed in flight.

RE: 3W70 engine problem
 

Have you tried a different battery. I had a similiar problem and it proved to be the battery. Run it for a few minutes and it lost it's omph. Let it rest and it started the cycle all over again.

RE: 3W70 engine problem
 

Sounds like may be battery to me.

RE: 3W70 engine problem
 

Hi,

Do you have the new style 3w ignition (2 magnets and small sensor) or the old style ignition (1 magnet and large sensor)? If you have the new style ignition, these symptoms are consistant with a low voltage from the battery to the ignition.

Elson

RE: 3W70 engine problem
 

I had a 3W 106 do this and I sent the Ignition to AI and they replaced the two diodes and plug caps. This fixed the problem. It would run fine for a few minutes and then start missing real bad.
Carroll

RE: 3W70 engine problem
 

I have the old style ignition I have check the batteries a dozen or so times, Li-ion with 6V regulator and have tried a different regulator with no change but I will try the battery next.
And the choke is manual no servo and no fuel filter I have replaced the entire fuel system 3 times and even stripped the one out of another plane that was working and still have the same problem, have gone though the carb replaced gaskets, tried different fuels.
the ignition is the only thing that not been replaced.

Carroll-RCU described the exact problem. Now if you can tell me who AI is?

Wyldman

RE: 3W70 engine problem
 

AI is Aircraft International. www.aircraftinternational.com

RE: 3W70 engine problem
 

Thanks Dan I'll give them a call.
Wyldman.