SDS mag setting “not clear yet”

[Larry DeCamp]

Please bear with me. I am failing G3x run up test. Ross has advised just put in 97 top sensor and 88 bottom sensor. Still failing. My initial setup was ‘old style’ with timing light Resulting in @ 93 and 84. My question :
What does the pointer and flywheel marks mean. I turned the crank to tdc at case spitand set the pointer.Then set-he map to 10 up to 1200 rpm. The flywheel was marked at 10 btdc.
There is a 9 degree difference between Ross’s numbers and mine done as described above. Still fails run up vibration test. Any guidance greatly appreciated.

 

[Toobuilder]

...Still fails run up vibration test...

For those not in the know, can you describe this test?

 

[Larry DeCamp]

For those not in the know, can you describe this test?

The test is in the g3 software in adhrs config. It directs you to run up the rpm scale for 1 minute and return to idle. It scores you 0-100. 100 + is fail.
This could be due to gsu25 mounting insecure, cylinder misfire or CPI mag position not correct.. Garmin now discorages mounting the adhrs on the 460 efis( was ok “ when I did the panel.The plugs look great and mag check is equal drop so plugs seem ok. So, the timing is wrong, on brand new cato 3 blade is not well balanced. I will use my dynamic balancer as the final judge.

 

[Toobuilder]

So the G3x now evaluates how smooth your engine feels? Does it seem to run right to you? Said another way, if you DID NOT have this feature, would it pass a normal EOR check?

I have a hard time believing the ignition timing is so far out of bed that it's causing a "vibration" at idle. I suspect your problem lies elsewhere

 

[Larry DeCamp]

So the G3x now evaluates how smooth your engine feels? Does it seem to run right to you? Said another way, if you DID NOT have this feature, would it pass a normal EOR check?

I have a hard time believing the ignition timing is so far out of bed that it's causing a "vibration" at idle. I suspect your problem lies elsewhere

So the G3x now evaluates how smooth your engine feels? Does it seem to run right to you? Said another way, if you DID NOT have this feature, would it pass a normal EOR check?

I have a hard time believing the ignition timing is so far out of bed that it's causing a "vibration" at idle. I suspect your problem lies elsewhere

So the G3x now evaluates how smooth your engine feels? Does it seem to run right to you? Said another way, if you DID NOT have this feature, would it pass a normal EOR check?

I have a hard time believing the ignition timing is so far out of bed that it's causing a "vibration" at idle. I suspect your problem lies elsewhere

The problems start to exceed 100 after 1800-2000. However they are erratic

 

[RVbySDI]

The problems start to exceed 100 after 1800-2000. However they are erratic

I personally would start with evaluating the ADHARS mounting for vibration first before contemplating changing engine settings.

 

[Walt]

Measuring engine vibration during prop balance is a good indicator, next step to measuring Eng vibes is doing a spectrum analysis. I would not dive into engine settings based on GSU vib test. You can always just bypass the GSU vib test and come back to it later.
As for the timing, if you installed the magnets correctly and mounted the pickup correctly there’s not much room for error.

 

[Toobuilder]

In my experience the Lycoming is very insensitive to timing at rich mixtures and low RPM. I crank a lot of advance (compared to Ross’ recommendations) into my engines at idle because it sounds less labored and responds better to throttle, but even well outside that range it never is “rough”. Ross’ recommendation of the standardized magnet setting may not be “ideal” when compared to a timing light verification, but the differences are so slight as to be unnoticeable. I’d suggest that if you are getting an ignition misfire that’s causing roughness, it’s a poorly seated, constructed, or routed plug wire…. Not “ignition timing”.

 

[lr172]

Please bear with me. I am failing G3x run up test. Ross has advised just put in 97 top sensor and 88 bottom sensor. Still failing. My initial setup was ‘old style’ with timing light Resulting in @ 93 and 84. My question :
What does the pointer and flywheel marks mean. I turned the crank to tdc at case spitand set the pointer.Then set-he map to 10 up to 1200 rpm. The flywheel was marked at 10 btdc.
There is a 9 degree difference between Ross’s numbers and mine done as described above. Still fails run up vibration test. Any guidance greatly appreciated.

Very tough to get flywheel at tdc via case split due to parallax. Use dot on starter to get flywheel to 25 btdc. Install pointer and make sharpie mark on flwheel at pointer. Set ign map to 25 at 1200. Adjust setting with timing light support.

You need to set the ignition map back to 25 or whatever you prefer before doing the vib test. Running the engine at 1200 and 10* of advance will be rougher. Not much, but may be enough to push the test over the edge. That’s pretty far off the mark.

 

[Larry DeCamp]

Thanks to all for input. My immediate question is if you set the crank to TDC #1, then the pointer is aligned to 0 degrees (TDC) and mark the fly wheel 10 degree.
Then if the timing map calls for 10 degree from 500 to 1200 RPM, the light should flash the pointer at the 10 degree mark?? This has never been clear to me as instructions just say “ set the pointer” then adjusting the mag position value to align the pointer with 10 degrees mark should yield the final setting, right ?
Yes the map is returned to the SDS conservative setting for the run up test series that is failing.

Regarding the gsu25 mounting, my panel is rock solid due to the 90deg bent bottom edge fastened to top longerons and secured over the top by the boot cowl over the 460 EFIS. If this is not good enough, I suspect the cantilevered position of the gdu25 is sensitive condition for vibration. Garmin G3x assist says this is well known cause and Vans sell rubber isolators. Has anyone had success with that ? They also say if it “feels “ ok, flyi it like you dont have a g3x. The true failure will be if the AHRS red x’s from vibration. Next is prop balance check for second opinion on ADHRS failure declaration.

Plugs look good, tan insulators and high quality wiring and boots. Not sure how to dig deeper without putting on a scope, which I have. Since I dont have a ‘distributor’ like my dinosaur V8 used, the sensor would have to move 8 times on a LYC, Ugh ! Any suggestions ?

 

[Dustyone]

Thanks to all for input. My immediate question is if you set the crank to TDC #1, then the pointer is aligned to 0 degrees (TDC) and mark the fly wheel 10 degree.
Then if the timing map calls for 10 degree from 500 to 1200 RPM, the light should flash the pointer at the 10 degree mark?? This has never been clear to me as instructions just say “ set the pointer” then adjusting the mag position value to align the pointer with 10 degrees mark should yield the final setting, right ?
Yes the map is returned to the SDS conservative setting for the run up test series that is failing.

Regarding the gsu25 mounting, my panel is rock solid due to the 90deg bent bottom edge fastened to top longerons and secured over the top by the boot cowl over the 460 EFIS. If this is not good enough, I suspect the cantilevered position of the gdu25 is sensitive condition for vibration. Garmin G3x assist says this is well known cause and Vans sell rubber isolators. Has anyone had success with that ? They also say if it “feels “ ok, flyi it like you dont have a g3x. The true failure will be if the AHRS red x’s from vibration. Next is prop balance check for second opinion on ADHRS failure declaration.

Plugs look good, tan insulators and high quality wiring and boots. Not sure how to dig deeper without putting on a scope, which I have. Since I dont have a ‘distributor’ like my dinosaur V8 used, the sensor would have to move 8 times on a LYC, Ugh ! Any suggestions ?

Hey Larry,
Have a look at this Thread and read from Post #17, I hope the pictures make it clearer.
CPI Install RV-10

 

[Toobuilder]

Thanks to all for input. My immediate question is if you set the crank to TDC #1, then the pointer is aligned to 0 degrees (TDC) and mark the fly wheel 10 degree.
Then if the timing map calls for 10 degree from 500 to 1200 RPM, the light should flash the pointer at the 10 degree mark?

Yes, that works, but the easiest way is to set the engine to 10 degrees (static), then affix a pointer somewhere convenient, then mark the ring gear with high vis tape and a contrasting sharpie mark coincident with the pointer. Run the engine with the brain box limited to 10 degrees and then drive the tape mark into alignment with the pointer via the “magnet position” keys. The method I use allows you to place a mark and pointer in a “safe” location and I don’t have to read any numbers. It’s either on the mark or it is not on the mark.

 

[Toobuilder]

There is a 9 degree difference between Ross’s numbers and mine done as described above. Still fails run up vibration test. Any guidance greatly appreciated.

The difference between 97 and 93 is 4 degrees. Same with 88 and 84. Not sure where you came up with a 9 degree delta.

There is a physical separation of the two sensors and one is 9 degrees “downstream” of the other. That value is consistent between your findings and Ross recommendations, as expected. That value is a function of the machined in placement of each pickup on the single mount.

 

[Larry DeCamp]

The difference between 97 and 93 is 4 degrees. Same with 88 and 84. Not sure where you came up with a 9 degree delta.

There is a physical separation of the two sensors and one is 9 degrees “downstream” of the other. That value is consistent between your findings and Ross recommendations, as expected. That value is a function of the machined in placement of each pickup on the single mount.

 

[Ralph Inkster]

Note- timing lights, use a simple (non dwell adjustable type) timing lights