Differen managment on 1.5 SOHC

[PrecisionBoost]

Ok...... the O2 sensor is completely ignored at wide open throttle because the ECU will switch from "closed loop" operation to "open loop" operation.

Closed loop is one where the ECU looks at the O2 sensor and tries to adjust the fuel

Open loop is one where the ECU completly ignores the O2 sensor and runs the injectors off of maps stored in it's memory.


The fact that one lanos beat the other just means that the stored maps in the systems missing the O2 sensor are better.

Ok.... next.... the key is the word "leaded"

Leaded gas is no longer used here in north america in anything other than race vehicles.

Leaded gas will decrease the engines tendancy towards knocking.

It's the same effect as increasing the Octane of fuel.

Imagine you had two cars with two different ECU's

Car #1 was set up for crappy 87 Octane fuel while Car #2 was set up for 91 Octane fuel

Now imagine that you run both off of the same fuel

The ECU in Car #1 would be conservative to try and avoid knock while Car #2 would give more aggressive ignition timing.

The end result is that Car #2 would beat Car #1 every single time in a race if everything (weight and modificaitons were identical)

The manufacturer allways tries to make sure the timing is "safe"

However...... if you have the car that was designed for leaded gas and you use unleaded gas you are risking knocking/detonation.... just as you would if you had a car that required 93 Octane and you ran it on 87 Octane.

Don't get me wrong..... they may never have a problem..... like I said... the manufacurer will allways try and be "safe" so there is allways room to advance the timing a few degrees and get some extra power out of the engine.

Now.....the exhaust from Leaded gasoline will really screw up an O2 sensor..... so that is why they can't use an O2 sensor on the cars that are suppose to run on leaded gasoline.

As well the exhaust from leaded gasoline will tend to block up your average EGR valve in a matter of a year or two..... so putting an EGR in a car meant for leaded gasoline will make more problems than they solve.

If they are using leaded gasoline that also means that they don't care about emmissions.... and when it comes down to it that is the main purpose of the EGR.


If I were you I would stick with the O2 based system..... it will get better gas mileage because it's able to monitor the Oxygen levels in the exhaust.

For all out performance the other system might give more power.... but your car would be "less safe" when it comes to the possibility of knocking/detonation

[PrecisionBoost]

Oh.... if your going turbo you don't want the "leaded ECU" since you really have to be carefull with the ignition timing on a turbo car.

Turboing the car will make it more prone to knocking/detonation..... so you want to have the ECU that will retard the ignition and run "safe" igntion maps.

If your using an aftermarket management system with the ability to change timing (such as a Greddy Emanage) then you will want to retard the ignition.

Remember that at Wide open throttle (WOT) your ECU goes off maps and ignores the O2 sensor..... so all of your tuning with an aftermarket system will be based upon changes at wide open throttle.

When your at partial throttle the car will be in closed loop and the ECU will actually fight the changes you've made with the aftermarket system.

So...... using a rising rate fuel pressure regulator for "rough" fuel delivery is the best way to start as most aftermarket electronic systems won't give you enough ability to accomidate the turbo by themselves.

Basicly the aftermarket electronics are there to "fine tune" the fuel delivery and ignition (if you get one with that option)

A great example is Tom's GSi turbo.

We had a heck of a time with his regular 1:1 rising rate regulator...... even with the Emanage we couldn't keep the car from going lean.

In the end I added my RRFPR that had an adjustable rise rate

With Tom's regulator (1:1) the fuel pressure would rise 1psi for every 1psi of boost.

My regulator was a natural 10:1 which means the fuel pressure rises 10psi for every 1psi of boost.

Now that is way too much fuel and pressure.... but my regulator has a "bleed valve" that allows you to change that rate.

In the end I would guess that we turned it into a 2.5:1 ratio RRFPR and the A/F was absolutely perfect without adjusting values in the Emanage.

That is to say in this particular case we could have pulled the Emanage out and just used the RRFPR by itself.

That kind of situation is rare..... most of the time you will get a nice A/F ratio in some parts and it will go lean or rich in small RPM gaps.

That is where the Emanage comes in handy..... because you can adjust those small gaps to bring the ratio closer to where it's suppose to be.

[MMamdouh]

thank you very much Tom for the great answer

we don't have any leaded fuel in the country and i have no idea why are they still using those engines on daewoos... funny enough the fact that they use the O2 sensor engines in the version of lanos that got the full options while the A/C and PWS version gets the O2 less version... now my dad got the O2 version (with a 87 octane lable attached to the ECU wiring) and i got the O2 less version

now as far as my dad's car is concerned... will it be better to use the 92 octane "jumper" or whatever the thing is called that tells the ECU the octane number the car is using? we only use 92 octane here.

i haven't check my car to see the tag on that jumper on my car so i am not sure... if i decided to turbo my car so will it be safe to keep it at low boost and use 92 octane or higher to avoid knoking? or maybe use a 87 tagged "jumper to keep it safer??

MMamdouh

[PrecisionBoost]

Ummmm..... it's Chris..... Tom is GsiTurbo

I wasn't aware there was a jumper to switch between various octane levels.

Your dad would be better off with 92 and you would be better off with 87

The 87 will have the ignition maps retarded slightly and it will inject slightly more fuel.... both are "better" if your going with a low boost turbo.

How much boost are you thinking??

The 92 jumper used in conjunction with the 92 Octane fuel will yield better power and fuel economy.

[MMamdouh]

Ummmm..... it's Chris..... Tom is GsiTurbo

... really sorry Chris for this

I wasn't aware there was a jumper to switch between various octane levels.

i found it when i was tampring with my amplifier which is sitting on top of the ECU... posted a pic here and i was told it is octane level indicator
http://www.daewootech.com/forum/viewtopic.php?t=6267

Your dad would be better off with 92 and you would be better off with 87

The 87 will have the ignition maps retarded slightly and it will inject slightly more fuel.... both are "better" if your going with a low boost turbo.

How much boost are you thinking??

nothing serious... just 8 or 8 PSI as i am going to keep the stock internals

The 92 jumper used in conjunction with the 92 Octane fuel will yield better power and fuel economy.

OK... will someone be kind enough and post a pic for his/here 92 octane "jumper" so i can know which pins are crossed?

MMamdouh

[Daniel]

Hi MM,

From service manual there are four octane selections available: 83, 87, 91 and 95.
Your 87 octane plug has terminals 1&2 shorted.
Mine 95 octane plug has terminals 2&3 shorted.
83 octane has 1,2,3 shorted.
91 octane is open.






Daniel

[PrecisionBoost]

That's really cool...... until this post came up I had no idea that the ECU was that flexible.... once my 1.6L/1.5L hybrid is into my Lanos I might fool around with these jumpers just to see how much of a difference it makes.

[MMamdouh]

thank you both for the great feedback

i now know why or lanoses perform better with the plug removed... it simulated octane 91 which is the closest match to our 92 octane that most of us use.

again thanks to you all.

MMamdouh

[REY04]

my racer also has different f/a management. i thought the O2 was removed but when i tried to check other racers its affirmative.

[MMamdouh]

just to wrap things up... here are the four settings for the octane selection plug



MMamdouh

[Daniel]

Nice pics MM! May I use them for other forums?
BTW I don't know how you moved contacts without moving a thumb .

Daniel,

[MMamdouh]

Nice pics MM! May I use them for other forums?

sure thing bro... i have no problems with sharing information for the purpose of helping fellow woo owners

BTW I don't know how you moved contacts without moving a thumb .

this is called PRECISION my friend!

MMamdouh