Replacement for Quadrajet ECM
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Thank you for the comprehensive reply.
Taking a baby step at this project, let's say we want to install an electronic Quadrajet in place of a conventional unit. We want no more or less functionality than the traditional unit provided, which is namely:
Comments requested.
Michael
Taking a baby step at this project, let's say we want to install an electronic Quadrajet in place of a conventional unit. We want no more or less functionality than the traditional unit provided, which is namely:
- The primary metering rods responding to manifold vacuum.
- A manifold absolute pressure (MAP) sensor controlling the pulse width of the 10Hz signal, period. If this worked well enough, then more complexity could be layered on, in both hardware and software, modifying the pulse width with sensor readings from the TPS, ECT, O2S, etc.
Comments requested.
Michael
while (1) {
if (o2SensorIsReady) {
if (TPS < thresholdPartThrottle)
doIdleCircuit()
else if (TPS < thresholdWOT)
doPartThrottle()
}
doWOT();
}
if (o2SensorIsReady) {
if (TPS < thresholdPartThrottle)
doIdleCircuit()
else if (TPS < thresholdWOT)
doPartThrottle()
}
doWOT();
}
Once you go WOT, you’d want to hold the solenoid open.
I’m not sure how drivable this would be and whether or not the stock ECM is truly this simple. I’d expect there to be tuned-in-hysteresis in all the transitions to blend fueling and smooth things out.
Only time and experimentation would tell.
I’m also not sure what the behavior should be like for a cold O2 sensor. Observation of a stock ECM and MCS at below-threshold ECTs could give you a clue.
