Draker
Well Known Member
Looking for some things to try, technique or otherwise. IO-360-M1B. This has been my cold start process since day one:
For this new engine's first 60 hours, it has always fired right up on the 2-4th spin. Lately (last ~4-5 flights, 5 hours) this process has failed me. Starter spins strong, but engine does not catch. I've started having better luck with setting the throttle and mixture half way in while starting. I've also experimented with throttle full-in while priming with the pump. It still can take maybe 10-20 spins to catch though.
After the engine starts, there's a period of 30-45 seconds or so where the engine is running really rough, and requires half throttle just to keep turning. Hard to describe, kind of a on and off "braaaap... braaaap... braaaap..." instead of smooth running. As it warms up, it gets smoother and I need to slowly back off the throttle to keep RPM around 1000. Finally, after 1.5-2 minutes of warmup, it's running smooth, idles correctly, runs up well, and otherwise works like a champ. This post-start behavior also coincides with the start-up difficulty. The engine has not behaved like this for its first 60 hours.
I've had a look at all the easy things: Ignition wires, plug gaps, connections on all sensors and mags, air flow path through the filter and snorkel. The fact that it runs normal and strong after a brief warmup is puzzling too. I guess I'd expect problems starting = problems flying. Also, maybe it's just the cold weather???
I know I'm asking for an opinion war bringing up startup technique. I've read the 5,000+ threads on fuel injected cold startup technique, and most of them boil down to "this is what I've always done". If there's something obviously and explainably wrong in my procedure, I'm totally fine with changing. Last time I tried changing my startup procedure, I deformed my air filter, so I'm cautious about change.
- Throttle - OPEN to ¼" of travel
- Prop - HIGH RPM
- Mixture - RICH
- Fuel Pump Switch - ON for 5 SECONDS or until fuel pressure levels off
- Fuel Pump Switch - OFF
- Mixture - IDLE CUT-OFF
- START
- Mixture - MOVE slowly to RICH as engine starts
- Throttle - OPEN to max 1,000 RPM
For this new engine's first 60 hours, it has always fired right up on the 2-4th spin. Lately (last ~4-5 flights, 5 hours) this process has failed me. Starter spins strong, but engine does not catch. I've started having better luck with setting the throttle and mixture half way in while starting. I've also experimented with throttle full-in while priming with the pump. It still can take maybe 10-20 spins to catch though.
After the engine starts, there's a period of 30-45 seconds or so where the engine is running really rough, and requires half throttle just to keep turning. Hard to describe, kind of a on and off "braaaap... braaaap... braaaap..." instead of smooth running. As it warms up, it gets smoother and I need to slowly back off the throttle to keep RPM around 1000. Finally, after 1.5-2 minutes of warmup, it's running smooth, idles correctly, runs up well, and otherwise works like a champ. This post-start behavior also coincides with the start-up difficulty. The engine has not behaved like this for its first 60 hours.
I've had a look at all the easy things: Ignition wires, plug gaps, connections on all sensors and mags, air flow path through the filter and snorkel. The fact that it runs normal and strong after a brief warmup is puzzling too. I guess I'd expect problems starting = problems flying. Also, maybe it's just the cold weather???
I know I'm asking for an opinion war bringing up startup technique. I've read the 5,000+ threads on fuel injected cold startup technique, and most of them boil down to "this is what I've always done". If there's something obviously and explainably wrong in my procedure, I'm totally fine with changing. Last time I tried changing my startup procedure, I deformed my air filter, so I'm cautious about change.