ecm management
Melting Slicks
Joined: Feb 2001
Posts: 2,803
Likes: 358
From: Northville, MI
The PCM will adjust over time within certain limitations. Without logging a scan/log and looking at your duty cycle, LTFT, knock sensors, etc. It will take 40 ignition cycles to have your fuel trims to fully readjust. However, without a bi-directional scan/tune software you will never get it to an optimum condition. Every car engine runs slightly different from the factory, example my 2000 vette had LTFT's of -.2 at 1000 miles and my 2001Z has +2.7 around 1000 miles. The LS1 engine was never calibrated to run 87 octane from the factory and will pull so much timing your fuel mileage will drop considerably. If you only have the 87 octane available to get you to the next good station with 91/93 octane You will not notice much but to run 87 octane continuously, you run the problem of engine knock, lack of acceleration, power, etc.
Bottom line do not run 87 octane gas if 91/93 octane gas is available.
Bottom line do not run 87 octane gas if 91/93 octane gas is available.
