S/d
S/d
Posting Guru
Joined: Dec 1999
Posts: 1,903
Likes: 2
From: Copley, OH
S/d
Yes. The PCM (powertrain control module) receives inputs from the MAP (manifold absolute pressure), the ECT (engine coolant temperature), IAT (intake airtemperature), EVP (EGR valve position) and TPS (throttle position sensor) sensors. It looks at a multi-dimensional fuel-air-spark map and drives the injectors and the ignition advance per the functions built into the map. The HEGO (heated exhaust gas oxygen) sensor reads the output oxygen and compares it to expected values. It then trims the injector pulse width to maintian the correct fuel air ratio.
The problem that comes with modifications is that they can create too great a difference between expected and measured exhaust O2 values and cause the control system to hunt for a way to correct the F/A ratio. This can cause some severe drivability problems. If the modifications are too severe, they can drive the values right off the map and cause the system to go into limp home mode.
MAF (mass air flow) suffers none of these problems, it bypasses the expected values and just reads air and fuel and adjusts accordingly so it does not tend to crash on modifications but may experience some drivability issues.
The problem that comes with modifications is that they can create too great a difference between expected and measured exhaust O2 values and cause the control system to hunt for a way to correct the F/A ratio. This can cause some severe drivability problems. If the modifications are too severe, they can drive the values right off the map and cause the system to go into limp home mode.
MAF (mass air flow) suffers none of these problems, it bypasses the expected values and just reads air and fuel and adjusts accordingly so it does not tend to crash on modifications but may experience some drivability issues.
