How to Tune for Fuel Economy

[greymarooneightytwo]

Still, I don't know why I hadn't considered putting in a relay for the wires for the distributor and the stepper motor... seems do-able.

[ammachine390]

Still, I don't know why I hadn't considered putting in a relay for the wires for the distributor and the stepper motor... seems do-able.

You could do that for the electronic portion of going between bypassed and unbypassed. But you would still have to switch the distributor vacuum hose, and reset the ignition timing every time you switched back and forth.

[donnyeagle]

Here's the link. Maybe this guy doesn't know what his talking about. If he does; then one of the main things that switched the computer on and off is the coolant temp switch and the air temp switch. So unplug the air temp switch (open) and run a switch to the unplugged coolant temp sensor connector. That would switch it off and on. Hmmmm

[greymarooneightytwo]

Doh! I was thinking the needles would self correct and come out of full rich, but I spaced the vacuum line... but that could still be switchable, with enough work.

I wonder how hard it would be to retrofit an electronic distributor?

(something like this: http://www.hot-spark.com/)

It would sort of make the ECM Test a bit silly, cramming extra electronics in afterward... but on the other hand it would be interesting to see...

Difficult, and more work than the alternative in all honesty, but interesting to ponder none the less.

You could have a relay control the path to the distributor/ecm test bypass, and it could easily control an electronic vacuum switch for the carb, but I can't think of how you could automate the position of the stepper motor or the use of an electronic ignition controller to retard the timing...

Maybe such a thing exists, a standalone "two position/ two stage electronic ignition controller/ICU" that would allow you to switch between calibrated timings on the fly... if it doesn't it stands to reason that someone could make some money on such a thing... (though likely not in this crowd, at least, I don't think I'd want one.)

The real question is how easy would it be to tune the EI system to work with the existing ECM and COULD we find a way to easily have two stored timings that could easily be activated by the relay, and would it be possible to automate the position of the stepper motor? (seeing as it's a stepper motor it seems reasonable... but how would you sense the position to properly correct it?)


Ahhh, I think my mind might be telling me to sleep because I'm dreaming already.

(Besides my "Gronk kit" is scheduled to arrive in the mail tomorrow, so the sooner I sleep, the sooner it's here)

[donnyeagle]

Wow, I was thinking of a MUCH easier solution. I want to just turn the computer off or on not really control what it does. But thanks for the interesting post.

[eaglefreek]

Doh! I was thinking the needles would self correct and come out of full rich, but I spaced the vacuum line... but that could still be switchable, with enough work.

I wonder how hard it would be to retrofit an electronic distributor?

(something like this: http://www.hot-spark.com/)

It would sort of make the ECM Test a bit silly, cramming extra electronics in afterward... but on the other hand it would be interesting to see...

Difficult, and more work than the alternative in all honesty, but interesting to ponder none the less.

You could have a relay control the path to the distributor/ecm test bypass, and it could easily control an electronic vacuum switch for the carb, but I can't think of how you could automate the position of the stepper motor or the use of an electronic ignition controller to retard the timing...

Maybe such a thing exists, a standalone "two position/ two stage electronic ignition controller/ICU" that would allow you to switch between calibrated timings on the fly... if it doesn't it stands to reason that someone could make some money on such a thing... (though likely not in this crowd, at least, I don't think I'd want one.)

The real question is how easy would it be to tune the EI system to work with the existing ECM and COULD we find a way to easily have two stored timings that could easily be activated by the relay, and would it be possible to automate the position of the stepper motor? (seeing as it's a stepper motor it seems reasonable... but how would you sense the position to properly correct it?)


Ahhh, I think my mind might be telling me to sleep because I'm dreaming already.

(Besides my "Gronk kit" is scheduled to arrive in the mail tomorrow, so the sooner I sleep, the sooner it's here)

I really don't want to sidetrack this thread further, but honestly, you are WAY over thinking this. The Eagle already has an electronic distributor and a mighty fine one at that. You can send your distributor out to a competent distributor shop and have it recurved for your needs and run an MSD box for maximum spark. If you really wanted to ditch the computer but keep a carb and have modern ECU type control of your ignition, I would look into a Megajolt Lite Jr. I was going to go this route a few years ago but then decided to go with EFI, which I still haven't done. It does away with the distributor for spark but you will have to keep it to run your oil pump. http://www.autosportlabs.net/MegaJolt_Lite_Jr.

[greymarooneightytwo]

Either way what Donny is wishing he could do is pretty much impossible; although the ECM Test is easily reversed, without lots of extra junk and plenty of initial setup you would still have to pop the hood, there's no ECM Test on the fly...

Although, yes, you're right! The megajolt has dual, on-the-fly switchable ignition configurations... one step closer to futility!

I still can't think of a way to sense the position of the stepper motor though, so I'm ruling it impossible at present.

[BenM]

I still can't think of a way to sense the position of the stepper motor though, so I'm ruling it impossible at present.

I'm probably showing some age here... The Apple II 5-1/4 floppy drive used a stepper motor. When the computer booted the drive always made a rattling noise; that was the stepper motor banging the drive head against the end of its travel.

Once the stepper had reached the end of its travel then the controller just needed to keep track of movements, it didn't need to sense anything.

So, I'm guessing the ECM does exactly the same thing. They weren't designed too many years apart.

[BenM]

I really don't want to sidetrack this thread further, but honestly, you are WAY over thinking this. The Eagle already has an electronic distributor and a mighty fine one at that. You can send your distributor out to a competent distributor shop and have it recurved for your needs and run an MSD box for maximum spark. If you really wanted to ditch the computer but keep a carb and have modern ECU type control of your ignition, I would look into a Megajolt Lite Jr. I was going to go this route a few years ago but then decided to go with EFI, which I still haven't done. It does away with the distributor for spark but you will have to keep it to run your oil pump. http://www.autosportlabs.net/MegaJolt_Lite_Jr.

I bet it wouldn't take much to program an Arduino to replace the ECM. I don't know that anyone has replicated a computer controlled carb system before. It could be fun.

I think the last of the 4.0 engines used distributorless ignition as well. I think they used a cam sensor on a distributor base, but I've never seen one in person to know.

[greymarooneightytwo]

That same arduino board could replace the relay as well, and control the electronic vacuum switch.

Why didn't I think of that?

Have an egg! 

In all seriousness if someone wanted to go through the effort of designing and making one, I'd help invest.

The only experience I have with stepper motors is a frustrating defeat... I was trying to find a way to make scrapped hard drive motors into micro-rc engines... but was never able to figure out how to effectively pulse them right, they always hit a certain speed and would start to stutter.

I initially thought it was promising, due to the high rpms, but I eventually gave up.

[carnuck]

I really don't want to sidetrack this thread further, but honestly, you are WAY over thinking this. The Eagle already has an electronic distributor and a mighty fine one at that. You can send your distributor out to a competent distributor shop and have it recurved for your needs and run an MSD box for maximum spark. If you really wanted to ditch the computer but keep a carb and have modern ECU type control of your ignition, I would look into a Megajolt Lite Jr. I was going to go this route a few years ago but then decided to go with EFI, which I still haven't done. It does away with the distributor for spark but you will have to keep it to run your oil pump. http://www.autosportlabs.net/MegaJolt_Lite_Jr.

I bet it wouldn't take much to program an Arduino to replace the ECM. I don't know that anyone has replicated a computer controlled carb system before. It could be fun.

I think the last of the 4.0 engines used distributorless ignition as well. I think they used a cam sensor on a distributor base, but I've never seen one in person to know.

CPS on the bell and cam sensor in the hole where the dist lived. The coil packs suck because 1 would burn out and the head had cracking issues too.

[Baskinator]

Back to fuel economy, you may also be filling your gas tank at different rates depending on how fast the pump is flowing on a certain day. At fast pump speed, the Eagle will only take about 15 gallons because the fuel splashes up and triggers the sensor to shut off. This can be very deceiving for gas mileage unfortunately. With slower pump speeds, it will usually shut off around 19 gallons or so. Wagons have a 22 gallon tank, and the 2-door models have a 21 gallon tank. In order to fully fill your tank and get the closest possible estimate of mileage, you need to make an educated guess from the position of your gauge (provided that is also operational) and prior fill-ups. When my gauge shows 3/4 full, I know it should take anywhere from 5-6 gal. Then you have to pump as slow as humanly possible for the last 5 gallons so it won't shut off and hope that your estimate was in the ballpark.

I have a feeling this is where a lot of those "25+mpg" ratings come from (of course some are O/D Manuals). I'd say 20-21 is the best you'll get in 4wd w/auto stock, but heck that's still decent for a carb. Other things like ignition system, fuel delivery mods, weight, aerodynamics, tires, and gearing will have positive or negative effects on mileage. The Eagle has great potential for a 30+mpg 4wd vehicle, but not many have made their mods with this goal in mind.

[carnuck]

Also fuel in areas without alcohol shoved into it get you better fuel economy roughly equal to the amount of alcohol (when they did 20% here I had to shop around for non-laced fuel)

[donnyeagle]

So far I have found that when I get high mpg it is because of the topping off problem mentioned earlier. In a recent 700 mile trip I logged my mpg at each fill-up. I got 18.4, 16.7, 25.1, 15.6. This was all highway about 80% very flat roads. I have never had a car with that much swing in mpg so it seems like the top off problem is where the high mpg posts come from. I also made an adjustment to the stepper motor position half way through the trip. I started out very lean (backed out) then I changed it to full rich (all the way in) with really no change in mpg. So either this car will never get good mpg or I am trying to fix the wrong thing. Another thing I found on this trip was when I switched to 89 octain the engine seemed to run smoother with no hint of ping so thats what I will run from now on. Sadly that cuts into the cost per mile. I just very disappointed in this car as a daily economical driver.

Here's some interesting math. If I can improve my daily average mpg by 2 mpg I would save about $350 per year on gas (driving 250 miles per week). Since that is true if my low mpg problem is related to my Carter BBD I could replace it with a Weber or Motorcraft and pay for the new carburetor with the money I save on gas.

[greymarooneightytwo]

I've run 90 octane is most of my cars, as often as I can afford it.

Lots of people tell me I'm crazy and it's unnecessary (some even claim it's "harmful", but all of the gasoline up here is between 87-90, and if they sell 93 in places in the lower 48 states, then it seems reasonable that 90 isn't going to harm it)

It actually runs better, much smoother.