DFCO and Injector Indicator Light on 2004 Honda Civic EX 5spd

[BlueSTARS]

Hello all. I drive a 2004 Honda Civic EX 5-speed. I've just become seriously interested in hypermiling, since this is my first standard shift car.

I've been reading about the advantages of DFCO vs. engine-on neutral coasting (gliding?). From what I've read, DFCO is most useful when engine breaking is desired. If breaking is NOT desired, it's better to shift out. True?

Anyway, in my reading, I stumbled across this site:
http://techno-fandom.org/~hobbit/cars/squirt/

That site details the assembly and installation of a injector-firing indicator to a Prius in order to determine when the vehicle was consuming fuel. The idea intrigued me, but I'm a total novice to car modifications.

Does anyone know where I might find a good resource for installing such a light? I understand basic electronics: I can read the circuit diagram and solder and the like, and I have all the components on hand. I just don't know where I might find that panel ("the ECU plugs"??). Is it in the cabin or under the hood? Does such a thing even exist (in an accessible state, anyway) in my car?

Thanks in advance, and happy holidays.
-Eric

[warthog1984]

Far easier & cheaper to get a SGii and just check the IGN timing and/or iFCD.

[BlueSTARS]

SGii doesn't seem cheap to me. This project should cost less than five dollars if I do it correctly. Plus, it's a lot cooler.

[Right Lane Cruiser]

While true, the ability to plug and play in any vehicle with a few setup changes as well as the ability to read and clear CEL codes can pay for it in short order. Additionally, if you are dedicated your fuel savings (earned by modification of driving style using the gauge as a guide) can pay for the device in a remarkably short period of time. I was able to save enough in just about 3mo of usage.

[BlueSTARS]

Yeah, I plan on getting one eventually if I find hypermiling to my tastes. Until then, I'd rather not shell out $150+ for it.

I am still interested in the location of the ECU hookups for my car. I heard it is under the passenger seat, but couldn't find anything. Any ideas?

[KJSatz]

I don't think you need to make an indicator light. Do a little test. Find an empty street, get going about 25mph in 3rd, and take your foot off the gas. A little under 1000rpm you'll feel it stop engine braking and "free up," almost like you're in neutral. That's when DFCO ends. Before that (maybe around 1400rpm) it'll start to feel like there's less braking, but that's just because the engine's turning slower so there's less drag. Well I have driven a 6th gen Civic EX MT and an 8th gen Civic LX MT not a 7th gen like yours though.

In general it is better to get into neutral earlier instead of using DFCO and brakes, but if you need to brake, you might as well be in gear! I've found you don't need to shift as much like 4-3-2...if you are in 5th, let it drag its feet to about 1200rpm, then downshift to 3rd until 1200rpm and then go neutral. I've found that works will. If you weren't in 5th go straight to 3rd.

Take advantage of how low our 5th gear is (well it is like this in the 6th and 8th so I'm assuming), like 2000rpm at 45mph. If you're going faster than about 36 not accelerating and flat I'd recommend being in 5th or neutral.

Good luck!

[abcdpeterson]

Originally Posted by BlueSTARS

From what I've read, DFCO is most useful when engine breaking is desired. If breaking is NOT desired, it's better to shift out. True?

Yep DFCO Only if you need engine breaking.

but hooking up a gauge...

How about we look at it this way….
(That link makes it look doable but…. )
How much of a benefit would the DFCO indicator light be?

I understand your reluctance to spend $150. (it IS worth the price)

If you hook up a DFCO indicator light what will you do with that info?

There is no trick to getting the engine into DFCO.
Maybe look at it this simplified way. Assuming your car can do DFCO.
With a warm engine take your foot off the gas, that’s it your in DFCO.


I am not trying to push you into a Scangauge. But having one… I can tell you that my car won’t do DFCO until the engine temp is over 130f and RPM’s are over 900. but there is not much I can do about it. If I need to break I use engine breaking before hitting the breaks. If the engine is warm I get DFCO, if not I don’t. Knowing that doesn’t change my driving much.


good to see your looking into getting more info on how your car is working!
the more you know the easyer improving FE will be.

[BlueSTARS]

Yeah, at this point, it's more about the fun factor than anything else. I've found that the ECU hookup I'm looking for is behind a panel next to the door on the passenger side. I still can't figure out the clip that holds it on. I keep feeling like I'm just gonna break the plastic in half.

After I figure this out, I'd also like to put in a shift light, at some point. That would be useful, in case I was just flat out too tired to remember where I wanted to shift. Also, with the stereo cranking at night, I sometimes have to reach down to remember what gear I'm in. A glowing green light would let me know.

Thanks for the info about DFCO, though. I have felt it kick in before. It's actually a really cool idea. I read some other site (obviously not very high quality) that said never to engine break if it could be avoided to increase FE. I feel much better being able to take advantage of one of the chief features of a manual without feeling guilty.

[abcdpeterson]

Originally Posted by BlueSTARS

Yeah, at this point, it's more about the fun factor than anything else. I've found that the ECU hookup I'm looking for is behind a panel next to the door on the passenger side. I still can't figure out the clip that holds it on. I keep feeling like I'm just gonna break the plastic in half.

After I figure this out, I'd also like to put in a shift light, at some point. That would be useful, in case I was just flat out too tired to remember where I wanted to shift. Also, with the stereo cranking at night, I sometimes have to reach down to remember what gear I'm in. A glowing green light would let me know.

Ok well, cool. If your have the time, yep it can be fun.

Interesting idea on the gear indicator.
Driving home Tuesday I was having a hard time keeping the speed up and still getting good FE. Then I noticed… oops I should be in 5th not 4th.

Another project you may find fun…. Radiator fan indicator.

[hobbit]

Well, the location of where you'll want to tap is going to be different
between my Prius and your car, so you'll have your own version of "ECU
plugs" area. You probably want to have your own wiring diagram at
hand, so you know which wire to read the signal from.
.
I would suggest that an injector light is useful while learning your
own car's quirks, because data read from the diagnostic port with an
SG or similar often lies in certain conditions. For instance, various
engine-run figures "freeze" at some nonzero values in the Prius when it
goes into shutdown mode, and the only way I can be sure is watching
the little blinkie. Just build your circuit so it doesn't load down
the injector output excessively, and keep in mind you're going to be
seeing pulses over +100 volts as they close. You DON'T want to diode-
suppress those between the injector and the ECU, either, because it
slows down close time and may trigger errors from the ECU about bad
injectors.
.
I really like the gear-indicator idea for auto trannies, and would
probably have such a beast implemented if I was forced to drive one.
.
_H*