02-27-2008, 08:03 PM
Advance Your Timing for Better Power & Efficiency
PSD Injection timing can be changed EOT Mod
The PCM uses the EOT to help determine the injection timing. Cold oil has more advanced timing. Warm oil has less advanced timing. There are several reasons Ford changes the timing as the oil warms-up.
In the past some modifications were tried on the EOT sensor. Most results were not successful. My early experiments resulted in the vehicle stalling at a red light with a woman driver.
But this modification is different. In the past the sensor was replaced with a fixed resistor. There was no feedback from the sensor. The engine could be made to run well at only one oil temperature. The changes in engine oil temperature needed to be sensed by the PCM.
The new method had to wait for the warranty to expire on the test vehicle. The new method requires cutting a wire and splicing in a resistor.
The EOT sensor is connected with two wires. Either wire can be cut and spliced with a resistor. The values that have been tried are: (0.5k 1k 1.5k and 4.1k). The 4.1k ohm has the most effect on advancing injection timing. When this resistor is wired in series with the EOT, the PCM is fooled into thinking that the engine oil temperature is lower than actual. Lower engine oil temperature causes an advance in timing.
The advance in timing seems to be good for efficiency. Power is better above 1500rpm. The turbo seems to have a bit more lag and it is now possible to run more injection oil pressure.
In general, new engines are not adjusted for peak power or efficiency. Part of the specifications requires lowering the peak combustion temperature. This is often accomplished by retarding the injection timing when the engine is at the torque peak (2000rpm). An advance (over stock timing) at this rpm is good for both power and efficiency. The test hill showed a 3mph increase in speed.
The increase in turbo lag seems to be caused by reduced heat in the exhaust manifold. Turbochargers work on waste heat in the exhaust gasses. Less waste heat is good for efficiency and this modification leaves less heat in the exhaust to run the turbo on the test vehicle.
One last comment, when the injection oil pressure is increased, the injectors are harder to open. Harder to open injectors will take longer to open. In the past, this effect has limited the injection oil pressure to about 3000psi on the test vehicle. Some people also reported that their engine towed better at higher rpm without an increase in injection oil pressure (without a 10k resistor). The advanced timing of this modification has allowed the injection oil pressure to be increased on the test vehicle. Haven't had time to gauge the increase but the injectors are working better at high rpm and load.
is this mod any good