Quote:
Originally Posted by
Randy@ddmworks
Most engines are destroyed during WOT runs, this is when the stresses are at their max. The ECMs will not throw a lean code during WOT. They are only monitoring Closed loop operations. For a lean code to trip, the LT & ST trims must max out past 20% error for a continuous period of time. In our ECMs Fuel trim monitoring and correction are disabled during WOT or whenever PE(power enrichment) mode is active. Also, stock Narrowband O2 sensors are not sensitive enough of the correct operating range.. They on read Rich or lean...no in between. The only two ways to monitor the safety of an engine at WOT are, EGT (exhaust Gas Temps) or Wideband O2 sensors. This applies wether it's a NA, Turbo, Supercharged, or Nitrous'd engine.
I've seen the terms used and have an idea what they mean, but could someone provide definitions and an explanation of how they all work?
LT trim
ST trim
Narrowband
Wideband
When does it transition to PE mode, wide open throttle only? Is PE mode control a function of how the ECM is programmed (open loop)?
I've heard the ECM's "learn" and adjust to actual operating conditions - octane, small mods, etc. What is the limitation of how much the ECM can compensate???
Thanks!
P.S. If this is too much to answer, a reference to an article would be great. Just trying to understand how it all works. We have 3 sensors - air flow on the intake, and two O2 on the exhaust. What else provides inputs to the ECM - Throttle body position, RPM, Air Temp,....