2000StreetRod
Moderator Emeritus
- Joined
- May 26, 2009
- Messages
- 10,597
- Reaction score
- 334
- City, State
- Greenville, SC
- Year, Model & Trim Level
- 00 Sport FI, 03 Ltd V8
While performing my WOT runs for my custom tune by James Henson it was discovered that my knock sensor was frequently retarding the spark advance up to 8 degrees. I assumed that the knock sensor was detecting my timing chain rattle as detonation and the PCM was performing as designed to prevent engine damage. Since I had a wideband air/fuel ratio gauge to monitor during WOT testing, I was able to determine if the fuel mixture was actually dangerously lean. Since it never was, James provided me with a tune that greatly minimized the knock sensor intervention. Upon completion of the custom tune James provided me two versions (with and without knock sensor intervention).
Just prior to beginning my timing chain repair saga I programmed the PCM with the knock sensor intervention enabled custom tune. I made sure that the engine started and idled normally (with chain rattle) and then pulled and repaired the engine. This morning I performed my first brief WOT run after eliminating my timing chain rattle. I had a fresh tank of 87 octane gas with up to 10% of ethanol. Upon reviewing the data log I was disappointed to observe as much as 8 degrees of knock sensor retard.
My next fuel tank fillup will be with premium fuel. Then I'll perform another data log. If there is no significant change in the knock sensor intervention and my A/F ratio is not lean then I'll assume there is no detonation problem. There may be another noise source that the sensor is detecting as knock or the sensor could be defective. I won't have any dyno testing done until I get the ignition advance right.
Just prior to beginning my timing chain repair saga I programmed the PCM with the knock sensor intervention enabled custom tune. I made sure that the engine started and idled normally (with chain rattle) and then pulled and repaired the engine. This morning I performed my first brief WOT run after eliminating my timing chain rattle. I had a fresh tank of 87 octane gas with up to 10% of ethanol. Upon reviewing the data log I was disappointed to observe as much as 8 degrees of knock sensor retard.
My next fuel tank fillup will be with premium fuel. Then I'll perform another data log. If there is no significant change in the knock sensor intervention and my A/F ratio is not lean then I'll assume there is no detonation problem. There may be another noise source that the sensor is detecting as knock or the sensor could be defective. I won't have any dyno testing done until I get the ignition advance right.
