Found usefull info. when leanning out mixture will result at timing advance at wot.

"One of the main side effects of changing the airflow with a SAFC, is the profound effect it has on timing. The timing map in the ECU is set up as such: the ECU looks at the engine speed and the airflow (actually the airflow per rev, but we wont go there right now), and then finds the point on the timing map. The timing map is just set up like a spreadsheet, with the columns representing either engine speed or airflow, and the rows representing the other. The tendency of the timing map is that lower airflow (less load on the motor) gets more timing advance. This is for a couple reasons, but generally lower load means less heat and less cylinder pressure, which means you can use more timing advance to get the mixture to combust at the correct point. The effect this has is that if you reduce the amount of airflow that the ECU sees, it will move down on the timing map, and you will get more advance."








Here is what judge gto said on timing.


Once you learn how to identify the factory timing marks, and to which way the engine advances timing then you move on. The leading spark plug is the engines main spark plug. Timing needs to always be adjusted using the leading 1 spark plug. Trailing 1 gets adjusted later.
Depending if you have an electronic distributor, 86 to 91 crank angle sensor, or adjustable timing EMS like haltech, micro tech, Motec, Autronic, etc,etc, engine needs to be revved to about 4,500 rpms to view total timing advance with a timing light.(total timing advance is when the ignition timing will not advance any more, when the engine is revved) At this point make your adjustments to the leading spark plug.

 

Reving engine to 4500 rpm does not put full load on afm, doesnt that mean you wont see total timing advance that way?

 

Set the timing to stock using the factory procedure and do not use an SAFC to lean out bigger injectors, only richen if it is lean (at least on a turbo car). Of course then you may have too little advance.

People have gotten away with reducing the airflow signal (a negative correction in the SAFC), but there is no point in doing this these days when you have Rtek's and other systems available now. You can datalog timing advance on an Rtek 2.1 and it will be accurate provided your pulley marks are correct. Why trick your engine computer when you can reprogram it? I wouldn't recommend an SAFC to anyone with a turbo car these days, not with the affordable options out there. Also, reading a timing light with the car parked is pointless beyond setting base timing.

This side effect is known in some circles. A lot of Vr-4 guys say "bigger injectors advance timing" but what they really mean is, their use of piggybacks to lean out bigger injectors results in greater timing advance.

 

my wot on my n/a is high 13s and lowering it maybe give me more power. i got myself a safc2.

also got an egt, should give my some idea of timing retard since temps will go up with timing retard.

So, low load rev 4500 rpm wont show full advance on timing light?

 

EGT may not react quickly enough to see any changes.

 

my egt reacts within 1-2 sec of wideband. becides 3rd and 4th gear pulls are slow.


1st 2nd gear arent good for reading both.

 

Judge gto stated 4500 rpm will show full advance when using a timing gun. true or not true?