controling air/fuel mix for better milage

[Calgaryturbo]

Here is my thought. I do alot of flying in small planes and they all have mixture control for the engine. Can you buy a mixture controle device to manualy lean out the mixture when you are crusing down the highway or not driving the car hard? I realize I would have to also get an a/f guage so there is no risk of running too lean. Maks sense to me. I think my TWG is running too rich all the time and therefore burning too much fuel.

On a plane when you are setting up for the most eficient fuel burn you just lean out the mixture until you have a small RPM drop and then reichen it slightly.

Part 2
I recently changed my oxegen sensor from a generic 3 wire to an NGK
sensor (f*#*ing expensive) and am getting worse milage. I did get alot of pinging at higher boost levels with the old sensor and I am wondering if this was caused by a lean mixture which resulted in better MPG.

[sammydafish]

I recently changed my oxegen sensor from a generic 3 wire to an NGK
sensor (f*#*ing expensive) and am getting worse milage.

what NGK sensor did you use? Isn't the factory one a Bosch sensor? Dirrect fit ones are only like $85.



This would be possable with the configurable output of a wideband controler. I've givin it some thought and will try it on my car with my R-500. PLX is supposed to be adding an update so you can configure it through software instead of throug the device, since it will take a lot of tinkering to get right I've been waiting for that to try it.




I also might build a device specificaly for this purpose. The general idea would actualy be to allow the use of ethanol blended fuel without a fuel economy penalty. Ethanol burns stoichiometric at a lower AFR than gasoline. This is why cars take around a 30% fuel economy hit when running ethanol blended fuel if the car wasn't flex-fuel designed. An O2 sensor circuit that could be coupled with a fuel quality sensor would alow regular cars to be switched to ethanol easily. The modified O2 would report to the ECU a signal that looked like gasoline lambda when its reading lambda for ethanol. Some tests have shown economy losses only 5-10% with reprogramed ECUs. This is due primarily to the fact that ethanol has less energy than gasoline.

[Calgaryturbo]

I would be very interested in hearing your results if you build somthing to control mixture. I'm sure the computer sets the A/F to the best overall perfomance and if it could be manually controlled maybe it could be leaned out for highway cruising and be more efficient?

Q: Where does an A/F guage get its reading from? Is it easy to instal?

Not sure what model of NGK O2 sensor it is but I will check. It was like $250.00 can My parts guy looked it up in the NGK book and the legacy was listed there. I assumed it would be better than boche because the NGK plugs and wires are so much better. Maybe I should have done a little more research here bofore buying it.

The car is running great now though, much better than with the generic sensor (I think it was for a ford escort). I have no pinging at high boost and very smooth acceleration. My MPG might be related more to my right foot!! The car pulls very hard at 15PSI now!

[Subtle]

Calgary

Check out www.sdsefi.com

There is such a feature is on their ecu, which is also used on Subaru powered light air planes.

Got one on my twgn --it almost flies

Ps they are in Calgary--your namesake.

[Calgaryturbo]

Hey Subtle
What did you pay for your set-up and why is this ecu better? I am in Calgary often so maybe I should stop in and chat with the guys there.
I would love to have more control over the engine.

Greg

[Subtle]

SDS the name is Simple Digital Systems.

One of the fastest GT-3 cars in SCCA is going to FI this season(that's from Mikuni carbs) and it's being set up with the SDS.

Not too expensive, straight forward to tune even at the track.

[sammydafish]

I don't know if you want to go into the world of independent engine management. The SDS unit is a good one, but it's an entire replacement for your factory system, which means lots of custom wiring and endless hours of tuning and working out bugs. The end result could be more power and economy because you can control the engine much more precisely, but the investment to get there (time and money) may not be worth it. Generally people don't go this way until they have some serious amounts of mods and hacks on the factory system don't work well anymore.

[Project_Legacy]

couldnt you just get an S-AFC to use if you are running too rich? and if you do that, you would have to get an A/F gauge too so u can monitor it right?

[Calgaryturbo]

That sounds more simple. What the heck is an S-AFC.
Somthing air fuel control? How does it work?

BTW found out my oxegen sensor is fine. It has the same perameters as the bosch one.

[Project_Legacy]

its something air flow convertor. at least thats what was on the box. the shops i went to said it was around 300 dollars though. pretty pricey. maybe u can find a used one? maybe i can find a used one?? LoL. o yea the brand i saw was made by apexi. maybe u should check those out.

[sammydafish]

couldnt you just get an S-AFC to use if you are running too rich? and if you do that, you would have to get an A/F gauge too so u can monitor it right?

no, an AFC or similar fuel comupter only works during open loop. so for performance it works since it modifies the fuel curves at WOT. when you're at part load closed loop operation, the stock ECU is making adjustments via O2 feedback, so if there is a change from an AFC, the computer will attempt to correct for it. That's why my idea of the O2 sensor modifier would work.


BTW, you can do this with a PP SMT6. You can tune the O2 output using it. If you do though, you can't use it for WOT tunning, so you'd need two if you wanted to do both.

[Subtle]

dafish

SDS ecu comes with wiring specifially for the ej22t or whatever

[Project_Legacy]

dafish

SDS ecu comes with wiring specifially for the ej22t or whatever

ooo it does? very nice indeed.

so an S-AFC still wouldnt be good to use? i actually am not running an O2 sensor at this moment though. the computer cant correct that if its not connected right??

[sammydafish]

then your MIL is lit and it's either in limp mode or it's reading the lack of O2 signal as 0 and trying to correct for a full lean condition making it as rich as it can.

Pre-OBDII systems often don't have the curcuits to accuratly check the condition of the sensors they are hooked up to. They more often just trust that the sensor is good. One reason why somethinkg like a bad or missing O2 might not always throw a code.



With the SDS, even if they have a harness for the EJ22, you still need program it. It's still a LOT of work.

[Calgaryturbo]

sounds like the SDS ecu is what I am looking for. Their page says it is around $1000. I will have to save up for that.

[sammydafish]

if you go that way, don't forget you'll need a DIS2 or something like it to get spark

[Subtle]

On the ignition side, I think all you need is a post-1998 coil pack.

It comes with a contol pad that is used to dial in the appropriate advance and A/F for varying loads. Don't need a lap top.

There is also a pot to slightly change the mixture.

[hackish]

In my opinion the SDS is junk. It lacks many features necessary for good driveabillity. It is very simple and that's why it's inexpensive. I find even megasquirt is better and that's not saying too much.

Your idea of leaning things out will rely on cylinder balancing. Similar to the GAMI (sp?) injectors available for aircraft. SDS does not support cylinder balance. It doesn't even support sequential injection.

Many of the new cars are using lean running modes. Unfortunately it causes slugish performance and that's why they use drive by wire. The enleanment procedure in the aircraft consists of leaning things out, throttling up to regain cruising speed then repeating the procedure. On a car it would require you to step on the gas more. Fortunately the drive by wire can be programmed to do this without you knowing. As soon as you step on the gas it pops out of the lean running mode and let's you accelerate under power.

SDS definitely does not support electronic throttle control. I am not aware of any universal stanalone that does...

-Michael

[dzx]

Actually my safc II controlled fuel all the time. Otherwise I wouldnt have been able to run with my 550 cc injectors, even at idle. It stands for Super air/fuel controller.

[NICO]

what about a greddy e-manage, its a simple piggy back. you could lean it out no problem and there cheap now.

[free5ty1e]

I thought the S in S-AFC stood for Simple. Because that's what it is...

I say just let the ECU handle things unless you really want to get into engine management... yeah it runs pretty rich but it's also pretty safe. IMO it's not worth it to modify for fuel economy only... the benefits probably wouldn't add up to the cost and effort needed.

[hackish]

Here is a solution... Get a wideband that has a narrowband output with a remapping function. Then remap the narrowband output so it switches over around 15.1:1 instead of 14.7. This should allow the factory ECU to trim out on the lean side during cruise. I generally tune turbo hondas to be a tad leaner under cruise conditions and have lots of reports that the car got better mileage than when new. I think the newer Techedge widebands support this feature.

-Michael

[sammydafish]

Actually my safc II controlled fuel all the time. Otherwise I wouldnt have been able to run with my 550 cc injectors, even at idle. It stands for Super air/fuel controller.

it does modify the AFM signal all the time, but in closed loop the ECU is adjusting indector pulse width in order to achieve the target AFR. In your case, you added more fuel that the ECU didn;t know about, so you had to modify the AFM signal to make the ECU think there was less air so that it would put in less fuel and return to the stock configuration under part load closed loop conditions. The ECU was still targeting a 14.7 (usualy) AFR

Here is a solution... Get a wideband that has a narrowband output with a remapping function.

that's what I said in the 2nd post of this thread. Without reprograming the ECU or going to a stand-alone, it's the only way to do it.

[Project_Legacy]

man i was looking for something simple too. the only reason why i wanna lean out a lil bit more is that when i race, sometimes it jus pops and doesnt go anywhere. i think it happens when i jus slam on the accelerator instead of easing it on. i dunno i jus wanted to see what my options were.

[dzx]

An safc II would be your best bet for simple and affordable. They actually work good.