EGR Mod

[ontarian_frog]

Why? get better gas mileage.

How will it get better gas mileage? It will use more EGR when lifting (partly) the throttle (I.E.: on a decline when the throttle is partly lifted) so that engine braking is reduced (manifold pressure increased*). If manifold pressure is increased*, the engine is performing less braking, less braking equals better mileage caused by having no oxygen in the combustion chamber. No with no oxygen, there is no fuel needed to be burnt. Therefore you get better gas mileage.

*Increased manifold pressure is used in the correct way, meaning pressure is closer to atmospheric levels. When the engines idles, when vacuum is at near maximum, at around 5psi. If one atmosphere is 14.7 psi, then there is a vacuum, or less pressure in the manifold. If you increase pressure in the manifold, you get closer to atmospheric pressure of 14.7 psi, where manifold vacuum is nearly non-existent. Enough with the science, if you don't get this, it doesn't matter for the installation and tuning part.

Here is where I got the idea: http://www.autospeed.com/A_110555/hD...s/article.html

The guy got 3 percent better mileage with his Honda Insight, I bet we get better results with the Aveo. The Aveo, believe it or not, uses the same EGR system as the Insight. The system uses a sensor and lift valve.

How it works: If you alter the sensors output to make believe to the ECU that the valve is less open, the ecu will open the valve more, letting more EGR flow.

[ontarian_frog]

Here is what you need: A simple 10K Ohms 10 turn variable pot and a digital multimeter

How to do it:

1. Both wires will be dark green, the one we want is connected somewhere on the ecu. With a multimeter at the Ohm setting, find the green wire that reads 0 O Ohms at the ECU connector and EGR sensor. There are not that many Dark Green wires on the ECU connectors.

2. Cut the signal wire far away enough so you can splice both ends. See picture 2.

3. Connect the pot like on the first picture. You might want to extend the wires to the cab so that you can make adjustments while driving.

4. Turn pot all the way to one end and measure pin 1 and 2 on the pot with a multimeter, using the Ohm setting, to make sure it reads 0. If it reads 10 000, then turn the other way.

5. At 0 Ohms, the signal is unaltered and the EGR system running at factory settings. As you increase the resistance, the ECU thinks the vavle is less open than it really is, and will open it more, letting more EGR flow in.

6. While driving...Slowly increase the resistance. You might find that the car starts to be jerky and not as smooth. back off until all signs of erratic engine running is gone. Might be a good Idea to let someone else drive or increase the resistance. Remember: Safety First.

7. You are done. Congrats. Now measure your increased mpg.

The beauty of this is the way the system works, the ECU has no way to find out the signal is being altered (unless you ground directly the signal, then it would trigger a CEL). Another thing is that at normal highway speeds and Wide open throttle, the ECU uses no EGR whatsoever. It's only part throttle that gets EGR flow. That means this mod should give you better city and combined mpg. Enjoy.

Here is how to wire the pot:


Here is the wires you need:


This is what our EGR valve looks like, although this is from another car:


Now I have not tried this yet, but as soon as I can get my hands on a variable 10K Ohm pot, I will. They are kinda hard to find here. eBay should have tons though.

[aveodude]

You do know that when you lift the throttle at highway speeds and just let the engine slow itself down, your injectors are not injecting anyways.

[mikedudley17]

yeh this was a hot topic on css.net

they were sayin when they were engine braking, if they reset thier mpg calculator on their consoles, it would read 99.9 for their gas mileage because the injectors are injecting just enough fuel to keep the car running, basically, allowing the motor to use the compression and wheels turnin the trans to keep itsself goin-i think. id need to verify it unless someone can say for sure.

[aveodude]

hook a wideband up to your car. You will see it shoot lean off the scale when you do it since there is no injector flow.

[ontarian_frog]

You do know that when you lift the throttle at highway speeds and just let the engine slow itself down, your injectors are not injecting anyways.

If you read correctly I mentionned, partly lifting the throttle, not completely. Partly lifting the throttle when you drive on the highway is the same as when you are going down a slight incline on cruise control. The ecu backs off a bit but not totally. That is where you want EGR and that is where the engine uses it. Make it use more of it and increase MPG. On the highway you won't see a significant increase just because there is very little throttle play, but in the city, you are constantly playing with the throttle, you could see some major gains.

EGR is mostly used in the city anyway. In lean cruise mode at higher speed, at wide open throttle and closed throttle, the engine does not use EGR at all. Remember, this is not a mod that ends all mods. The best way to improve your gas mileage is still to improve the way you drive. But this mod unlocks potential mpg that would otherwise never be gained. If getting 5% better mileage, to me is a step in the right direction.

[mtlswift]

You do know that when you lift the throttle at highway speeds and just let the engine slow itself down, your injectors are not injecting anyways.

Yeah, it's programmed to stop injecting during coasting at >40 mph (~70 km/h). I wish we could reprogram it to work down to, say, 10 mph... that would be more useful in fuel savings.

[ontarian_frog]

You do know that when you lift the throttle at highway speeds and just let the engine slow itself down, your injectors are not injecting anyways.

Yeah, it's programmed to stop injecting during coasting at >40 mph (~70 km/h). I wish we could reprogram it to work down to, say, 10 mph... that would be more useful in fuel savings.

Problem is at that speed, the engine would jerk and probably stall.

[mtlswift]

at 10 mph? No, I've shut down the car to "acc" in gear at 10 and it's coasted fine. then I turned it back to "on" and it fired up again, as a manual's supposed to...
If you're worried, then 20 mph... but 40 is way to high to be useful. I think the Yaris/Corolla cut off is a lot lower than 40 to, which is why they have better fuel economy.

[AVE0SAM]

hmm this could be interesting....interested to see results before i go cutting anything