Have a 99 qx4 that has the 3.3l engine on it. How does the ECU/ECM retard or advance the timing?
Thanks!
Timing Advance/Retard
Re: Timing Advance/Retard
Before the ECU the engine must be in a physical condition of meeting the needs to be timed. The basic static timing of the engine must be met.
The ECU has many inputs, gas, MAF, static timing, barometric pressure, engine speed and load to name just a few.
The ECU is a dynamic device and through math and other algorithms sensing and switching tries to keep the combustion first off in order and tries to maintain perfect combustion burn rates as per the needs of the engine at all conditions.
The basic firing order is done pre ECU as is the basic timing. Advance and retard of timing is for the mechanical side to catch up to the electrical side of the timing issues. The mechanics of a rotating engine at various speeds can be determined but to have a spark at the exact time takes a lot of engineering, not only the mechanical aspects of fast and slow movement of large masses of pistons, valves and gears but the mating of induction of gases, induction of electron movement and then placing these actions and reactions into one machine to work at the most effective timing to create the bang of the cylinders at the right time.
There are many theories involved within the ECU, as there are within an internally combusted engine.
The ECU has many inputs, gas, MAF, static timing, barometric pressure, engine speed and load to name just a few.
The ECU is a dynamic device and through math and other algorithms sensing and switching tries to keep the combustion first off in order and tries to maintain perfect combustion burn rates as per the needs of the engine at all conditions.
The basic firing order is done pre ECU as is the basic timing. Advance and retard of timing is for the mechanical side to catch up to the electrical side of the timing issues. The mechanics of a rotating engine at various speeds can be determined but to have a spark at the exact time takes a lot of engineering, not only the mechanical aspects of fast and slow movement of large masses of pistons, valves and gears but the mating of induction of gases, induction of electron movement and then placing these actions and reactions into one machine to work at the most effective timing to create the bang of the cylinders at the right time.
There are many theories involved within the ECU, as there are within an internally combusted engine.
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jhong1226
- Posts: 48
- Joined: Wed Jun 30, 2010 6:30 am
- Car: 1999 Infiniti QX4 2011 Nissan Altima 2.5s
- Location: Ingleside, IL USA
Re: Timing Advance/Retard
Manually you can adjust the timing by rotating the distributor, Im wondering how the ecu do this since the rotor is fixed and i dont see any mechanical device inside the distributor, rotor still touches the cap terminals at exactly the same time everytime. My scanner does show a timing change almost every time the gas pedal is pushed or let go. goes from 15 BTDC to even at 40+ btdc depending on engine rpm and loads.
Im just baffled on how my engine is doing this without physically rotating the distributor. I can see this working on a Distributorless set up since the spark can be delayed or advanced right at the ignition coils.
Im just baffled on how my engine is doing this without physically rotating the distributor. I can see this working on a Distributorless set up since the spark can be delayed or advanced right at the ignition coils.