First Start Woes

[ctennis]

Similar issue with my prop. Multiple starts, RPM tests, times, could not get it to cycle. I was certain I removed the plug correctly, though that was what everyone questioned. I removed prop governor and checked gasket, etc. All good.

Finally read on here someone had similar issue and they had crud in their oil supply line from governor to prop. I removed both ends of the line and blew it out with shop air, and got out a lot of the preservative oil that was still in the line. After that, it cycled wonderfully.

[Chris Engler]

Thanks guys...really appreciate the advice on this. To clarify, this is a fuel injected motor (completely stock IO-400). Sounds like either the fuel pressure is actually too low or I have a gauge out of calibration.

Regarding operation of the pitch lever, we've run the motor above 2000 rpm with the pitch lever advanced for a couple of minutes, cycled the prop, etc. with no joy.

I spoke with WW this morning and they are sending a governor that they bench tested and verified to be working correctly. I'll install this week and hope for an easy answer that the MT governor is somehow non-functional.

Carr - very interesting situation with the nose bearing.... we'll keep that in mind if all the other trouble shooting options don't pan out.

[Chris Engler]

Ctennis - excellent idea.....we'll pull the oil line and confirm.

Carr - follow up question....was you engine a Superior as well?

[n82rb]

As to fuel pressure, check the part number on the pump. It would not be the first time an engine was shipped with a low pressure pump on a injected engine or vice versa.

Bob burns
Rv-4 n82rb

[Carr]

Chris

Sorry I didn't back to you sooner. (out of town)

My engine was a Lycoming 0-360 A1A.

Did you solve your problem?

Carr

[Chris Engler]

No worries Carr ? I know how that business travel has a way of getting in the way of airplane fun!

Yes, happy to report that the prop mystery is solved though a bit embarrassed by the simple solution. The XP 400 has a small ?set screw? type plug in the back of the hollow section of the crank and sure enough it wasn?t there (it is now and hence the prop is working flawlessly).

This was one of those self-induced problems. The engine shipped set up for a CS prop and early in the build was going to use the ground adjustable Sensenich prop so had the A&P remove the set screw and install the forward seal in the crank. As the build progressed, decided to go CS and when we re-converted, pulled the front seal and forgot the rear plug.

During the trouble shooting process, I was working with Whirlwind on possible solutions. I want to acknowledge their outstanding customer service throughout the process. I was on the phone with them a couple of times a day and they even shipped out another governor for me to try to eliminate that as one of the variables (all at no cost). Fortunately I didn?t need to do the swap governors since we found the missing plug first. These days it's hard to find customer service that includes an actual person answering the phone when you call and knowledgeable staff personally committed to helping work through issues and going the extra mile?BIG thank you to WW!

Now that the prop is working, I?m focusing on the second issue ? engine cough at high RPM:

The engine starts quickly and things are smooth until 2450 RPM then it sputters and coughs hard with mixture full rich. I can lean to about 2/3 rich mixture and advance the throttle fully and it smooths out but the RPM never gets above 2500. This is all with the prop at low pitch.

At this point I don?t think it?s fuel related as the fuel delivery system has been thoroughly checked as follows:

1. Fuel flow test to the inlet of the fuel servo ? just under 60 gph delivered with the electric pump running.

2. Pulled screen to the inlet of the fuel servo ? no sign of debris.

3. Spoke to the folks at Precision Aeromotive (the servo is a EX-5VA1) and they suggested the following to confirm fuel delivery system: Just before coughing starts (2450 RPM) with mixture full rich, lean to peak and just past. Should be a 150 rise in EGTs to peak which it is. Per Precision, that suggests that mixture is neither to rich or too lean prior to coughing. At that RPM setting, EGT spread is 60 degrees or so hottest to coldest across all 4 cylinders so it doesn?t appear to be a fuel servo/injector issue.

The only ?modification? to the fuel system since delivery from Superior is that I rotated the fuel servo 180 degrees to get the orientation of throttle and mixture levers were I needed them for the cables. I?ve confirmed with Superior and Precision that this is fine/not a factor.

Based on the above, my main focus is the ignition system. I?m running slick mags modified for the G3i ignition system. So far love the system as hot and cold starts are super easy and the engine runs very smoothly below 2400 rpm. At 1000 rpm, turning the system on and off results in a 20 rpm increase/decrease (system on +20) and can feel the engine run smoother as compared to the ?straight mag? mode. My theory is there is an ignition issue at the high RPM setting and that when I lean, I?m matching the fuel delivery to the max RPM the ignition system will allow which is why it smooths out but RPM doesn't increase. Just a theory and I have very limited knowledge regarding the slick mags.

I?ve had the A&P check timing (and rechecked again yesterday) and it?s spot on. I?ve seen a reference to an ?internal timing? and not sure if this is the same thing the A&P is checking or something else. I also read that a bad condenser in the mag can be attributed to these symptoms. The cough is present regardless of the G3i being switched on or off. In the ?off? mode, operation should be ?mag only?.

Any thoughts/advise would be much appreciated.

Thanks!

[birddog486]

If you get a chance, try this simple test. Run the engine for a couple minutes to let it warm up. Do a full power run up at FULL RICH until the engine starts coughing. Bring the engine back to idle and then shut it down. Pull the top plugs after it cools and let us know if you see any difference in them.

I've seen this symptom once personally with an engine swinging a FP prop but I'm not sure if it would act the same with a constant speed. It's hard for me to believe you'd have the same issue but since this is a new engine it's possible.

If all the plugs look the same disregard this post.

[lr172]

Originally Posted by Chris Engler

The engine starts quickly and things are smooth until 2450 RPM then it sputters and coughs hard with mixture full rich. I can lean to about 2/3 rich mixture and advance the throttle fully and it smooths out but the RPM never gets above 2500. This is all with the prop at low pitch.

I am an FP guy, but it was my understanding that max RPM is set via an adjustment on the prop (limits how fine of a pitch is allowed). Have you performed the adjustment? Overly limiting the fine pitch would create the symptoms your seeing. I would assume that the factory would ship with a conservative setting to help people from inadvertently over-speeding prior to adjustment. I don't believe that ignition issues would limit your RPM to 2500 without showing other symptoms as well. I can produce well over 2500 RPM on only one mag. That said, bad coils demonstrate that behaviour at times. However, you can usually feel the strange nature and in your case should see diverging EGT readings across your cylinder pairs.

Larry

[Chris Engler]

It's funny I'm at the airport now and just finished up a call with Thomas at g3i. We had exactly the same thought that the governor setting on the fine pitch is to course to allow the engine to spin up to 2700 RPM. I did confirm the fuel flow continues to increase even as the engine is coughing indicating the injection servo is doing its job and feeding more fuel as the throttle advances. If the governor is holding the prop back to less than 2,700 we would see the flooding symptoms that we have including coughing and black smoke. Hopefully this is the cure!