Jeff Rose/Electroair EI Mechrep

osxuser · #1 04-09-2010, 12:00 AM

Ok, so I'm gonna just go ahead and call it a Mechrep (like a Pirep, but I'm not the pilot of this particular bird).

One of my customers with an O-360-A1A powered 6a has been fighting high CHT's for the last year or so. It seemed to start after we replaced the carb with an overhauled one, so we did the research, changed the jet, and otherwise made sure the induction system was in good shape.

I went up on a test flight with him after that work was done, only to find some ALARMINGLY high RATE of CHT increase at takeoff power settings. I say this because I fly with the same engine in the Cardinal, and while we have the same high CHT problem, the RATE of increase is a lot more even and slow. At the same time, there had always in the back of my mind been a little warning about what the ignition system was doing, it was acting different than I thought it should on runup, but the owner thought it was fine.

Having eliminated fueling as being the issue, I checked the mag timing, which was of course fine (I say of course, because I've worked on this plane for the last 3 years... timing doesn't just go out that fast typically, and I check it every condition inspection). That left the EI.

The Symptom: On runup, in the past, when the mag was switched off, the RPM would drop dramatically (200ish RPM), than come back up as the EI advanced the timing. What was happening this time, was the EI would lose the 200 RPM, the EGT's would shoot up, and then it would keep slowly loosing RPM until the engine started to bog... Switch back to both and it would come back. My determination was that the computer was for some reason dramatically RETARDING the timing (which was causing the fuel to still be burning when it came out of the valves, thus the sharp rise in EGT).

Once convinced of that, and with no other ideas as to what could be causing the problems, we sent the computer off to Electroair to be checked... just got word today that it was in fact BAD, so we are getting replacements and should have that all back in about a week to retrofit and reinstall. This unit is around 12-15 years old, and has over a thousand hours on it. Not too shabby.

I'll report back when we get the new system installed and wrung out to see if this solves more of our problems, or just the runup issues.

rocketbob · #2 04-09-2010, 06:16 AM

Did you try disconnecting the vacuum advance box? The timing should stay fixed if its disconnected. As RPM comes up it does in fact retard the timing...at idle it should be running 40 degrees advance.

David-aviator · #3 04-09-2010, 06:46 AM

The report is a good reason to have the little meter that tells you where the timing is at at all times. I had the Jeff Rose system on an earlier engine and that little gage told the story - about 32 on taxi, 24 on take off and began to advance in climb as manifold pressure decreased.

I would not fly with EI without an indication of where the timing was.

rvmills · #4 04-09-2010, 10:23 PM

Nice report Stephen...thanks for the detailed info.

I have a fairly new Electroair, and am not surprised that Mike and Co are taking good care of you...nice folks!

Couple questions, for the sake of troubleshooting, should I ever see a similar indication.

Did Electroair describe the failure mode (ie, what it was or was not doing)?

Was the unit actually turning off when the switch was turned off? I ask this, because I'm trying to figure out how the unit would continue to retard the timing after it was turned off. The initial RPM drop is when the EI stops advancing the timing and providing a spark, thus only the mag is sending a spark at its fixed 25 deg, right? Scratching my head on why the RPM would continue to decay and the EGTs would rocket up, if the EI was just turned off. I know the timing is adjusted contnuously, through the start and then while running, based on MAP, but just trying to figure this one out...odd one for sure!

My EI computer has a green power light, but not sure if the older units did. Your description gives plenty to look for, and perhaps the green light not going off when the switch is off may be another indication to troubleshoot with, should issues arise.

Been very trouble-free so far, and good to have this info for the hip pocket. Thanks much!

Cheers,
Bob

See ya at the races again this year?

osxuser · #5 04-12-2010, 09:20 PM

The one installed on this RV isn't the same system that is currently offered from what I understand. This one is an all in one unit, without the option for displaying timing advance, and has no indication on the panel at all. When it's switched off by the mag switch, it's not doing anything from what i can tell.

If you didn't know it was installed, it acts just like another mag.

Rockyjs · #6 08-16-2010, 09:40 PM

Stephen,
I stumbled on this link researching high CHTs. I'm troubleshooting a very similar high CHT problem on a friends RV8 with an IO-360 and an ElectroAir installed on the right . For the most part the engine runs smoothly but doesn't seem to develop full power. After a very short taxi of 4 minutes I see high temps approaching 400 on all cylinders shortly after takeoff. We are getting 16 GPH fuel flow at takeoff and I've flow checked the fuel injection system. The engine has good compression, so the last thing is the ignition. There is no indicator light or gauge for the ignition. Did the new ignition help with your customers CHTs? I have a spare Slick at my hangar that I'm planning on swapping with the Electorair unit and see if that helps.

Rocky

zilik · #7 08-17-2010, 07:02 AM

You might try checking the timing of the EI using an automotive strobe timing light. With #1 cylinder at 25 degrees BTDC place a mark on the rear of the flywheel inline with the case halves. You'll need to disable the map sensor if installed so the ignition will default to 25 BTDC. Start the engine and check the timing with the strobe light.

I'm also a fan of aviation plugs. REM37BY's work well with the EI as they're designed for the engine.

Rockyjs · #8 08-18-2010, 06:59 AM

It's coming back next week so I will check the timing. It has aviation plugs, not sure which ones from memory. Thanks for the advice.

Schmeddz · #9 08-27-2010, 04:10 AM

The Electroair ignition is actually an Electromotive ignition set up for airplanes. For the full tech data you don't get from Electroair, go to this link. http://www.electromotive-inc.com/manuals.html
The new ignition design is an XDI from Electromotive. Depends on what you have. The post from OXUSER says there is no place to check the advance. The older Jeff Rose ignition is an Electromotive HPV-1. It does have a provision for the advance timing that you can read on a voltmeter. On the "ADV" tab on the HPV-1 you can see the voltage of your actual advance in millivolts. If you can hook a meter to the ADV tab and put the meter in your cockpit you can read the amount of advance while flying. (Don't forget a solid ground.) See page 17 of the HPV-1 manual. I have an LCD meter element I found on Ebay installed in my cockpit. The meter was all of ten bucks with free shipping. Nice big blue backlit digits that are easier to read as I'm getting older. I use shielded wire to the ignition ADV since millivolt readings are easier to mess up with all the engine electric noise. The LCD works off of aircraft power bus.
I talked to Jeff Rose years ago about my installation and he was a great guy and very helpfull. I bought an XDI for my next engine. (Saved 300 dollars) I'm still running an HPV-1 for almost ten years now on the flying plane. You don't get all the extra data in the manuals from Electroair that you will get from Electromotive. I have found these systems to be pretty bomb proof barring any wiring issues. (90 percent of problems are usually wiring related, so it goes.)