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01-05-2011, 04:32 PM
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Join Date: Jul 2009
Location: Dundas , Ontario , Canada
Posts: 192
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Digital Tach Lag ?
Hi Guys,
I'm in the process of modernizing my RV-4 and have ripped out all vacuum and engine instruments and replaced them all with the new MGL Xtreme EFIS/EMS .
Everything seems to be functioning but I'm curious about my RPM indications .
There seems to be a lag in indications , most noticably on start up and shut down . I don't get any RPM indications for 2-3 s on start up and the RPM's show the idle RPM for a few seconds after shut down . Mag checks are also less responsive .
Is this life with a glass tach or is there something wrong with my setup ?
Any suggestions or comments are appreciated !
Marc
__________________
1993 RV-4 C-GVMT
Formerly N144RS
SN 1444
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01-09-2011, 05:55 PM
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Join Date: Jul 2009
Location: Dundas , Ontario , Canada
Posts: 192
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I'm sure there a bunch of you using EMS's from Dynon , GRT , MGL , etc...
Could I get a pirep on how responsive your RPM indications are ? Is there any perceived lag ? More at low RPM's VS higher . I've never flown behind glass in a piston plane so don't know if what I'm experiencing is normal.
Thanks,
Marc
__________________
1993 RV-4 C-GVMT
Formerly N144RS
SN 1444
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01-09-2011, 06:34 PM
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Join Date: Jan 2005
Location: Charlotte, NC
Posts: 1,523
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What you're describing doesn't sound right.. I've never seen it on any other system (GRT, Dynon, etc..)
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Radomir
RV-7A sold
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01-09-2011, 07:54 PM
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Join Date: Oct 2005
Posts: 75
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MGL Tach
I have a MGL tach in my Ercoupe. I never notice a lag during startup or when I shut the engine done, but then I don't know if I've ever checked. I have noticed a lag in my run-up, doing a mag check. When I put it on one mag , either left or right it takes a few seconds to adjust.
Russel Koch
RV9A
Working on everything.
finishing, panel and controls
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01-09-2011, 10:26 PM
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Join Date: Mar 2007
Location: Grand Island, NE
Posts: 192
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High Frequency/Low Frequency
I have a MGL Infinity Single (small 2 1/4 engine monitor). I had the same issue with the MGL engine monitor. If memory serves me correct there is a low frequency and a high frequency setting for RPM. When I switched it to the right one (don't remember which one) the lag in RPM went away. I would bet your MGL EFIS has the same setting.
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Steve Barger
RV-7A slider
Aerosport Power O-360
My RV was born in Reno, but now lives in Grand Island Nebraska
Phase I completed, enjoying Phase II
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01-11-2011, 08:53 AM
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Join Date: Jul 2009
Location: Dundas , Ontario , Canada
Posts: 192
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Thanks for the input !
Marc
__________________
1993 RV-4 C-GVMT
Formerly N144RS
SN 1444
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01-11-2011, 08:57 AM
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Join Date: Oct 2007
Location: Salmon Arm, BC
Posts: 933
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Dynon and P-Mag
I have the small Dynon EIS connected to a P-Mag. Works perfectly, no lags whatsoever.
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Mark Olson
1987 RV-4 Sold
2003 Super Decathlon - Sold
F1 EVO Rocket, first flight May 31/14
First in line for the Sonex JSX-2T kit
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01-11-2011, 11:09 AM
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Join Date: Jun 2005
Location: Milwaukee, WI area
Posts: 2,967
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I have an Enigma, and I do have a lag. Hadn't heard about the low/high setting...will check on that, but it's normal with the RDAC-X unit from what I know. Not a big deal, and I'm used to it now, so I don't even really notice it...I will check on the low/high tho! 
__________________
Chad Jensen
Astronics AES, Vertical Power
RV-7, 5 yr build, flew it 68 hours, sold it, miss it.
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01-11-2011, 11:47 AM
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Join Date: Oct 2007
Location: Sacramento, CA
Posts: 3,351
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My GRT EIS has a small lag in RPM and even a bigger lag in MP. I have been told that this is due to filtering that is built-in in the EIS as otherwise it will be too eratic. The RPM lag is very little but consistant at all RPM (high or low)
I suspect most digital engine monitor have some sort of filtering.
Hope this helps
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Mehrdad
N825SM RV7A - IO360M1B - SOLD
N825MS RV14A - IO390 - Flying
Dues paid
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01-11-2011, 11:59 AM
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Join Date: Jul 2009
Location: Dundas , Ontario , Canada
Posts: 192
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Hi Guys,
I also posted on the MGL Forum and was told by Rainier that all the processing is done in the RDAC and there will be more lag with my 1 pulse per rev sender than a set up with a higher frequency .
The high/low setting is for the Infinity singles unit that does not use the RDAC interface .
I'm glad to hear from some MGL users that it's normal . Not ideal but normal !
Marc
__________________
1993 RV-4 C-GVMT
Formerly N144RS
SN 1444
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