How we can advance the timming?

[jorge]

How we can advance or decrease grades on the timming of my lanos?

[MMamdouh]

i don't think you can... it is controlled by the ECU so unless you got an engine managment that have such function, you won't be able to do it

MMamdouh

[BosnianLanos]

Why do you need to change timing?

If you're going with nitrous. A 50 shot requires a set of plugs with one heat range cooler without any need to mess with timing. Anything more than 50 would need a timing adjustment, but then you're asking for trouble because the engine can't cope.

Otherwise, aftermarket management, cam gears, or a custom ignition circuit would be the things to use.

[PrecisionBoost]

How about that Octane selection plug.... if it was changed to a lower octane then the car would automaticly retard timing slightly and inject more fuel.

Can't remember where the plug was, there was some talk about it sometime ago... I think MMamdouh might know what I'm talking about.

[Pir0]

I know what you\re talking about. Always wondered what that did, car felt faster when it was on the higher octane setting. All you do is unplug it, turn it round, and plug it back in lol.


Usually have numbers wrote on either side, or an A and a B. eg. 93, or 95, or 95 and 97 i think on a lotta vauxhalls here.

[jorge]

PrecisionBoost: You say the knock sensor but my car is had a hybrid engine with 1.6 engine block and 1.5 soch head and that sensor be eliminated because I have 1.5 ecu and this ecu not control that sensor anymore. But I want to control the timming to gain some hp. Maybe I need to purchase a adjustable cam gear but where I can buy it? I am from P.R. And what other trick I can do to do this like the map sensor? moving the sensors?

[PrecisionBoost]

Knock sensor?

I don't think the Octane selection plug has anything to do with the knock sensor.


I said Octane selection plug.... which is found on the 1.6L and 1.5L wiring harness

If I remember right it was located somewhere on the passenger side... perhaps under the passenger side seat.... cant remember


From what I gather about the operation the ECU wil........

With a "high octane" the ECU changes the injector map and timing map to make use of the higher octane ( advances timing and sprays slightly less fuel )

With a "low octane" the ECU changes the injector map and timing map to make use of the lower octane ( retards timing and sprays slightly more fuel )


The ignition timing will not be changed by an adjustable cam gear..... only valve timing events. ( assuming it doesn't have a distributor )

On an engine that used a DIS ( distributorless ignition system ) the timing for the ignition event comes off the notches on the crankshaft pulley which can not be moved or rotated.


The only way to retard timing is to add an aftermarket ignition system where it will allow you to pull timing based upon a number of factors such as boost or a "nitrous button"

[MMamdouh]

How about that Octane selection plug.... if it was changed to a lower octane then the car would automaticly retard timing slightly and inject more fuel.

Can't remember where the plug was, there was some talk about it sometime ago... I think MMamdouh might know what I'm talking about.

the octane selection plug is found right next to the ECU... i was wondering what did it affect and i was suspecting spark timing as well

http://www.daewootech.com/forum/viewtopic.php?t=6267

i am confused about the ECU's reaction... if you tell the ecu you are using very low octane (83 for example) then this fuel got high tendancy to ignight under pressure so i guess the spark should be advanced to burn the mixture bfore it burns on its own due to the pressure

on the other hand if i use octane 95 that have lower tendancy to burn due to pressure... then what good will it be to burn such fuel too early when it can be compressed more to give us more power when it is burned??

this might be a stupid question but i am having hard time trying to figure that out

MMamdouh

[PrecisionBoost]

I think your confused about the terms advance and retard with respect to ignition.


At idle your car will fire the spark plug at roughly 8 degrees before top deac center ( so before the piston reaches the cylinder head )

During normal driving your car will fire the spark plug at roughly 20 degrees before top dead center ( since the pistons are moving faster )

The idea is to start the combustion so that it really starts to build pressure just after the piston goes past the cylinder head.

Advancing the timing would mean that your igniting it earlier... so 5 degrees of advance means your firing the spark plug 25 degrees before TDC instead of 20 degrees TDC

Retarding the timing would mean that your igniting it later.... so 5 degrees of retard means your firing the spark plug 15 degrees before TDC instead of 20 degrees TDC.

Spark Knock is when the flame pressure builds up before the piston hits top dead center ( pushing downwards on the piston )

Detonation is when the Air/Fuel ignites before the spark plug goes off ( usually due to very hot spots on the piston or very poor gasoline )


So.... you were right about the fuel..... 91 Octane burns really quick.... where as 95 Octane burns slow.

So to get more power out of the 95 Octane you must advance the timing so that the spark starts off earlier ( say 25 degrees Before TDC )

With the lower octane that advanced timing might cause the flame front to build up too early and smack the piston as it comes up to TDC ( spark knock )


With a turbo or nitrous the fuel will burn quicker..... so you want to retard the timing slightly (spark later ) to avoid knock.

In really high power engines they will do their absolute best to get the ignition perfect so that the pressure wave hits the piston just a degree or two after the piston has passed TDC.


It's kind of like pushing someone on a swing..... if you get them at just the right time you can put lot of pressure on them and push them high.

However if they pass by you and your running to catch up then odds are your not going to add much energy to their swing.


So in short.... by selecting a lower octane setting on your ECU the ignition map will be slightly retarded by a couple of degrees.... which is perfect for turbo or nitrous.

And since a lower octane fuel also makes the Air/Fuel leaner..... the ECU will adjust to add more fuel by increasing the duty cycle of the injectors slightly.


Hopefully that explains the ignition events and why the selection of octane level can be to your advantage.

Chris

[MMamdouh]

dear Chris... that was very helpful indeed

thanks

MMamdouh

[exist3nce]

Yes excellent information post!