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-   -   EFII - the jury is coming in (https://vansairforce.net/community/showthread.php?t=125420)

Dorfie 05-07-2015 05:31 AM

EGT peaks
 
Jesse,
Do you find that the EGT's peak close to each other? I ask this in the understanding that in the standard injection system the fuel injected can be matched to the airflow of EACH individual cylinder. My understanding is that the EFII system injects the SAME amount of fuel to EACH cylinder, ie. not matched.
Thanks.
Johan

Jesse 05-07-2015 05:37 AM

2 cylinders peak early. Rob says that the injectors can be replaced with other injectors somehow to tune this out. I haven't looking into that yet.

BillL 05-07-2015 06:21 AM

Software or hardware limitation on injector trimming?
 
Quote:

Originally Posted by Jesse (Post 981020)
2 cylinders peak early. Rob says that the injectors can be replaced with other injectors somehow to tune this out. I haven't looking into that yet.

If you do dig into this, can you determine if there are individual injector drivers in the ECM? I think it was said they all fire together, but is that a function of making the maps easy, or a hardware limitation of the ECM. On diesels, there is a current driver board with one per injector. They can be "trimmed" to match to a certain extent in production, but in the field they are not changeable.

I would think that they might be paired, but not all injectors on one driver since they typically have a trigger amperage that drops to a hold amperage for operation.

Maybe too deep, and EFII should answer.

DanH 05-07-2015 06:50 AM

Quote:

Originally Posted by Jesse (Post 981020)
2 cylinders peak early. Rob says that the injectors can be replaced with other injectors somehow to tune this out. I haven't looking into that yet.

Interesting point. How early? Did you obtain a GAMI spread?

Hmm. Should be able to bench check a given injector, then bench check a selection until one with more or less flow (as desired) is found. A quick spin with Google says there is a whole cottage industry out there flow matching injectors, so the services are available.

rmartingt 05-07-2015 07:14 AM

Quote:

Originally Posted by Jesse (Post 980900)
The programmer shows RPM, MAP and a lot of other bits of info. However, it only shows rpm in the nearest even 250rpm increment. I don't think there is any interpolation involved.

Is there any confirmation on this? That is, if my RPM fuel value is 165 at 2250 and 170 at 2500, what is the value for 2375? Is it, 165, 170 or 167.5?

Quote:

Originally Posted by rv6ejguy (Post 980898)
The RPM Fuel Values compensate for VE changes only. Since VE only changes about 5% on a Lycoming every 250 rpm, in the effective powerband, this makes little difference in AFR. The number of injection events are proportional to rpm.

Basic fueling is the result of RPM Fuel X MAP plus a correction for IAT.

So let's say I want to run LOP at 24"/2400 and below, best power above that, running mogas, C/S prop, and I have an AFR meter. How would I do that? I guess detailed tuning would have to happen in flight to make sure temperatures don't hit limits. I guess the timing map helps alleviate some of the concerns?

I've been puzzling over this for a couple days now, and reading all kinds of articles on engine operation. I'm just not really familiar with the details of piston engine operation and theory beyond the absolute basics. Props were only briefly mentioned in school, and when they were they were always turbine-powered; the only engines I ever messed with were .40-class and .049 2-cycle RC ones.

BillL 05-07-2015 08:18 AM

Typically, a linear interpolation is done between map points.

Bluelabel 05-07-2015 08:18 AM

Jesse,
Thanks very much for the detailed write up.
From what I know, the set up is not really as involved as you mentioned. I've seen the spreadsheet for the data points and I recall it only being 2-3 pages.

Yes, it was my engine on the dyno at Barrett, and we certainly didn't get a chance to tweak anything or dial it in. It was still a good learning experience and I got to dive into the programmer.
Either way, we are all headed into uncharted territory and there's bound to be a learning curve.
I had previously spoken to Robert about setting up a database that we can all share our data and settings with one another and post our results. I know there's one other guy a few weeks out from being where you are and I'm right behind him. So by this summer, we should have enough data to start seeing some averages.
I'll pm you directly with a bunch of specific questions.
Nice work though.... Gotta love how smooth it runs.

lammers4699 05-07-2015 08:21 AM

Is that my project?
 
Hey Jessie, is that my project you talk about the one with EFII, as I had that already with my RV-10. Hope that it is all positive.

redbaron 05-07-2015 08:31 AM

RV=12 Viking enging system
 
I,m installing a VikingAircraft engine (Honda) in my RV-12. Dual batteries (EarthX36) plus standby, battery for the Dual G3X touch, Dual fuel pumps, Dual EII, Dual controls and switches. Thanks for your report.

bill@fusion4.net 05-07-2015 09:59 AM

Quote:

Originally Posted by lammers4699 (Post 981070)
Hey Jessie, is that my project you talk about the one with EFII, as I had that already with my RV-10. Hope that it is all positive.

It is/was yours... and it's a plane now.:)


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