Timing advance?

[JoeB]

I'm reading and learning, not a mechanic. I have a 99 Toyota Solara with a 3.0L V6 1MZ-FE. The ECU Toyota used is not rewritable. I use a Split Second FTC1 piggy back to control fuel/timing. I've been told there is no way to advance the timing, I can only retard timing. I've read here that one of the things I should do is to advance the timing with water injection. Any ideas? Thanks -JoeB

[dsmtuned]

Originally Posted by JoeB

I'm reading and learning, not a mechanic. I have a 99 Toyota Solara with a 3.0L V6 1MZ-FE. The ECU Toyota used is not rewritable. I use a Split Second FTC1 piggy back to control fuel/timing. I've been told there is no way to advance the timing, I can only retard timing. I've read here that one of the things I should do is to advance the timing with water injection. Any ideas? Thanks -JoeB

I don't know how your car works, so I am assuming here based on the way other cars do it.

You ECU should advance timing at lower RPMs and when you have a leaner mixture on the piggy-back control. Piggy-backs usually modify the signal from the intake air counting sensor to the ECU. To make a richer condition, you need to add fuel. When "adding" fuel, you are essentially tricking the ECU into thinking that there is more air coming in the intake and it thus increase tuel to match the air.

Most ECUs take have a control "map" (spreadsheet) that has lower timing values for increased air flow. That means when you are adding a bunch of fuel to combat knock, you are decreasing the timing advance that the ECUwill dish out.

Water injection allows you to run a leaner mixture without knock. So your ECU "sees" less air coming in the intake sensor, and will advance timing. So, yes, if tuned correctly, water injection will help to increase you timing.

Whew!! I'm out of breath now.

[mosk]

Think of it this way, Joe: Toyota tuned your Solara as a normally aspirated motor, and spent a considerable amount of time polishing the stock fuel and timing maps so that the car would run well in almost all situations (sea level, moderate altitude, hot, cold, bad gas, etc.). They gave the stock ingition curve as much timing as they could, within the safety margins for the worst condition they could reasonable expect. Then, on top of that, they equipped your motor with a knock sensor, so in the event of bad gas, heavy loads, hills, hot weather, etc., your ECU could remove/retard excess timing so the motor wouldn't ping.

Then, you added a supercharger. The supercharger dramatically increases engine's load and in-cylinder pressures. It increases the engine's load because it takes power to operate -- the parasitic nature of the beast, to the tune of ~35 hp at the crank for an Eaton MP62. It also increases the engine's need for fuel, because it is pumping more air into the motor. The flipside of these two behavior changes is that the increases in load in-cylinder pressure typically requires a decrease in ignition advance and/or an increase in knock resistance (higher octane fuel, more fuel as a coolant, cooler air charge, or, in our case, water injection). However, even with water injection, it is unlikely you will want to dial in more igniton advance than you had when the vehicle was normally aspirated, at least at peak load.

The inability to increase ignition advance beyond the stock value is the one real drawback to the FTC1. However, you can zero out the retard that the FTC1 "adds" and then use an OBDII diagnostic reader to see how much timing the stock ECU is removing via the knock sensor; unless you are running very little boost, I would expect to see that the engine still knocks in certain spots with the stock ignition map values, even with water injection. Because the knock sensor circuit is reactive, it isn't perfect, but it will give you a sense if you are leaving much on the table.

Personally, while there may be some areas of the stock map that will benefit from some ignition advance, most of these will be under very light load or even vacuum. The areas of the map that you enter during acceleration and WOT are (in all probability) NOT going to require more advance, although they should require a lot less retard than before the water injection.

Bottom line: you don't need to dial in more advance per se, although you will benefit from modifying the programming in the FTC1 so that you use less fuel (for cooling purposes) and less retard when the WI is active.

Hope this helps,

Jeff