Fuel Pressure Regulator
Here it is April 2004 and the car is still away in winter storage. Much of my spare time has been spent preparing and planning for it’s happy return. One of my goals is to get the fuel injection REALLY sorted out. Don’t get me wrong, the car is running stronger and better than ever but when sent to storage last fall there were changes to it’s computer profile yet untried. I have made a concentrated effort to better understand the minutia of multiport fuel injection optimization.
Electromotive’s TEC3 system has a built in tuning wizard designed to make the initial set up quick and easy. The wizard will get it running but there are many parameters to be fine tuned afterward. I was disappointed with the wizard’s recommendation and only yesterday did I realize why. The wizard suggested pulse width times, (called by TEC3 the “UAP” or User Adjustable Pulse width), that was much too short for my car making the mixture too lean. The car was not driveable at wizard settings at all.
I have been studying the TEC3 manual and taking the time to understand the math behind the scenes. The wizard suggested a UAP of only 75% of what experimentation made the engine run well. It finally dawned on me that the fuel pressure regulator, salvaged from a Datsun 280Z multiport system, was designed to deliver fuel pressure of 33lbs. The TEC3 bases it wizard on 44lbs of pressure! I was only running 75% pressure so it needed much longer pulse widths to deliver the same amount of fuel! I have just ordered an adjustable OBX universal regulator with a gauge and can’t wait to install it. Wonder if the increased pressure will give a better spray pattern and better atomization? My UAP times will need to be adjusted down accordingly.
Sitting around this winter has also given me time to review datalogs from the end of last season. One of the graphs is ignition timing and it can be reviewed in detail against engine temp, rpm, map sensor, throttle position sensor, and more. It became evident that at higher rpms the timing could stand another 5 degrees of advance. Under high loads the advance table peaked at 26 degrees but under light loads it was as high as 34 degrees. I have created a couple more profiles with the timing advanced to 31 degrees. Again I can’t wait to test it out. Right now the knock sensor is disabled but I need to think about enabling it again especially if the timing is to be peaked. When first setting up the engine the knock sensor was overly sensitive and would scale back the timing whenever accelerating, causing it to cough and sputter. Wonder if the TR6 engine is naturally so noisy that the sensor’s lower limit needs to be raised? Just something else to tweak.
I’m hoping to get it back from storage on April 10, 2004. And then there’s that supercharger. . . . .