The distributor is driven by the exhaust cam, and the base timing is adjusted by rotating the distributor body.

When the engine is cranking, the spark is triggered at the base timing, and the ECU is not involved. Once the engine starts, the ECU triggers the spark at an advanced time. The spark time is computed mostly from the air flow and the engine speed, possibly with other trim adjustments. However, vacuum and EGR are not involved in spark timing, except that the timing is likely adjusted when the ECU disables the EGR.

To adjust timing, you put the jumper in the test connector to set the ECU to test mode. This causes the ECU to disengage from timing advance, and allows the timing to go back to base timing. Then you would loosen the mounting bolt for the distributor, and rotate the distributor body until your timing light indicates the correct base timing. Then tighten the bolt, of course.

 

Thanks! I found some youtube videos that does this. And do you know how does the ECU interact with aftermarket ignition systems such us nodiz? For example, the oem ecu might detect missing ingnition coil and/or tps and some other problems around EFI might appear (im probably wrong but shouldnt be needed 2 tps in this case?). Im really new to this so i dont really know how all this really works. Maybe there is some literature about it apart from the bgb?

 

The ECU would not interact with the aftermarket ignition at all. It will probably indicate missing ignition and TPS all the time, and may go into some failsafe mode of operation. Don't know what will happen then, but the video you linked seems to be quite detailed, so I would see what the author did to make it work. I would not consider replacing the ignition unless I was replacing the entire control system. Is the problem that you cannot get parts to get the OE ignition working properly?

 

No there is no problem, i just want to understand as much as i can, to know how it works, what can fail, what can be adjusted and overall what possibilities i have. I will probably never change the control system but knowing that i can do and how to do it is just interesting

 

yes yes i know i want to do the opposite

 

Do not replace anything until you get your car running right. Otherwise, you will create problems faster than you can solve them. Check your ignition timing and set it to spec. Then you can be confident that your engine problems are not due to ignition timing, and you can set about trying to find the actual cause. For example, there could be a faulty sensor that is causing the ECU to compute an incorrect timing. Or, could be any number of other causes. However, trying to cover the effects is just shooting the messenger.

 

What does the air sound like?

 

it sounded like a high-pitched, sucking sound. I will make a post with a video of the sound once i repair some heater pipe and thermostat housing holes... i had to take out the fuel tank and its a pain in the ass.