JPI EDM units and Manifold Pressure

gbarrier · Post by **gbarrier** » Mon Sep 05, 2016 6:05 am

Think I have a crow to pick with JPI when the holiday is over. I know some of you have installed their units and wondered if you had the same challenge.

I just finished an install on the EDM 900 unit. Setup was a lot like the FuelScan 450 and pretty straight forward. They ask for a copy of the pages of the aircraft manual showing instrument limitations before they configure your unit. Ours came with the proper limits for all the primary gauges (oil temp., oil pressure, CHT, RPM) but I'm not happy with MP markings. The unit has a red radial line at 29" and when you exceed that on takeoff the red warning light comes on and the MP on the unit turns red. I understand the requirements for limit markings, etc. but this makes no sense. I reviewed the manual and it shows normal MP limits from 14.5 to 29. It does not however show red markings at 29, or 15 for that matter (and it has none at 14.5) like the manual does for oil pressure, temp, etc on the gauge. This kind of defeats the purpose of the warning when it flashes every time on takeoff. I don't want to be conditioned to ignore the warning.

Anyone else experienced this

aero101 · Post by **aero101** » Mon Sep 05, 2016 11:32 am

When are you seeing redline at 29" MP? I should think the only time under normal circumstances you might see redline is prior to engine start depending on baro pressure? I should think that at full power that shouldn't be a problem and you'll never see 29" unless you're super / turbo charged due to restrictions in air ducting such as air filter, throttle butterfly, etc, etc even at sea level... If this is not the case, please let me know that my assumptions are in error as I am quite curious?

Mog · Post by **Mog** » Mon Sep 05, 2016 4:07 pm

So the MP issue aside, would you recommend the JPI 900? I am essentially going to be forced to move to something other than the stock gauges due to inaccuracies and failures.

gbarrier · Post by **gbarrier** » Mon Sep 05, 2016 6:46 pm

Jim, I'm surprised too. Baro was 30.25. We're about 500 MSL so static should have been about 29.75 and that is exactly what it was. On takeoff it went just over 29 at about 29.4. I would have thought that it would have been lower. Obviously by 500 ft of climb all was well. I drug out my old MP gauge and sitting static on the shelf it showed just over 28". Not much help but guess that's what 12,000 hour does.

Mog, only you can decide that. My old EGT gauge was getting lazy because of some pretty old probes and I really wanted a newer CHT / EGT unit with lean find. When I compared pricing for just that combined with the fact that I didn't trust my old oil temp and a few other gauges prices weren't that different. I'm kind of an old school analog guy so I can take or leave the digital presentation but it is good. I also removed a JPI Fuel Scan and EI volt/amp meter both of which has much larger numbers that I get on the EDM. It's all a compromise. And it's not cheap. I paid about $3,100 for the unit and another $200 for wiring, hoses and ends. We did the install ourselves as well as the paperwork. I can see some people having $5,000 or $6,000 invested till they are done.

MS Pirate · Post by **MS Pirate** » Mon Sep 05, 2016 7:13 pm

Referencing the JPI 900 manual, it lists a 4 step process to correct the MAP reading based on altimeter. It states this process should only have to be accomplished one time.
Have you completed this procedure? It might solve your situation.
The manual also lists the procedure to adjust ("pilot program") other limits.

You can find this material online, if you don't have a hard copy.

gbarrier · Post by **gbarrier** » Mon Sep 05, 2016 9:23 pm

Yep, got the manual. You can adjust the MP reading a couple of inches. Setup seems really quite simple. According to the instructions though the 29.7 static looked right based on altitude and baro.

As best I can tell limits for "primary instruments" cannot be adjusted.

Are you using the 900? If so, how does yours behave.

MS Pirate · Post by **MS Pirate** » Tue Sep 06, 2016 6:32 pm

I have a JPI 830 and contemplating adding MAP to display.
I'd be interested to hear what you find from JPI on this issue.

On the 830, it appears that all "alarm limits" can be set by the user, where the 900 can only be "pilot programmed" on a limited amount of readings, from what you have experienced.

Curtis · Post by **Curtis** » Tue Sep 06, 2016 8:33 pm

I have the JPI 830 with the MAP and RPM. It is simple to set up using the instructions. Also, you can set all the perimeters by going into the program settings. There are actually two program settings.

gbarrier · Post by **gbarrier** » Wed Sep 07, 2016 11:30 am

Redlines on primary gauges are factory set and are not user programmable like so many other things are. That's the only way they got approval to replace the original primary gauges.

But not to worry. An email to support@jpinstruments.com last evening with scanned page from POH brought a return email this morning including a file to upload to the unit and the redline was gone instantly. Gotta admit that I am pretty impressed with customer service. Go JPI.

JPI EDM units and Manifold Pressure

JPI EDM units and Manifold Pressure

JPI 830

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