ROYMAC
August 16th, 2010, 03:05 PM
:help2:I'm working on my first tune. '96 Tahoe with 383 stroker motor, cam, headers, 9.7:1 compression, 0411 PCM swap, running only 91 octane pump premium. Overall the tune I'm running works pretty well, except at idle, right after I start the engine. It's not as bad once the engine gets to operating tremperature but it still idles like an old tractor - sometimes it will stall seconds after starting it.
I've been doing some logging. Have verified with an old fashioned timing light that the ignition advance showing up on my log matched pretty closely with what the timing light was saying. In my first log I found KR was pulling several degrees out of my timing. This is at idle, sitting in my driveway with the trans in Park. I strongly suspect the sensor is picking up valve train noise due to higher tension springs than stock and higher compression (slightly) than stock. There was no audible knock to be heard.
So I go into my EFI Live and learn that there are 2 types of knock sensors. The LS1 resonant type and the LS2 flat response type. I'm still running the stock sensor that came in the original vortec 5.7 Litre. How do I figure out which I have? It only has one wire attached to it. I am guessing that means it grounds itself through the sensor body to the block?
I don't want to get too far out into left field, but I tweaked B6226 Knock Sensor Frequency from 5.5 khz up to 6.0 khz, B6250 Knock Sensor Multiplier TPS up, as well as B6255 Knock Sensor Multiplier RPM up some. EFI Live says that increasing B6250 & B6255 desensitizes the sensor. I loaded this tune and relogged a short while. Looks like this removed the KR at idle and still no audible knock. However, this update had virtually no change in my poor idle quality.
Does anyone have any advice on how which knock sensor I have, and if my changes make any sense whatsoever? Yes, I'm a newbie at this game! Any and all help is appreciated.
I've spent hours reading through many threads here, all related to knock sensors and settings, etc. but it seems these little devils are a bit of black art - lots of questions, a few answers and many threads that lead nowhere.
I've been doing some logging. Have verified with an old fashioned timing light that the ignition advance showing up on my log matched pretty closely with what the timing light was saying. In my first log I found KR was pulling several degrees out of my timing. This is at idle, sitting in my driveway with the trans in Park. I strongly suspect the sensor is picking up valve train noise due to higher tension springs than stock and higher compression (slightly) than stock. There was no audible knock to be heard.
So I go into my EFI Live and learn that there are 2 types of knock sensors. The LS1 resonant type and the LS2 flat response type. I'm still running the stock sensor that came in the original vortec 5.7 Litre. How do I figure out which I have? It only has one wire attached to it. I am guessing that means it grounds itself through the sensor body to the block?
I don't want to get too far out into left field, but I tweaked B6226 Knock Sensor Frequency from 5.5 khz up to 6.0 khz, B6250 Knock Sensor Multiplier TPS up, as well as B6255 Knock Sensor Multiplier RPM up some. EFI Live says that increasing B6250 & B6255 desensitizes the sensor. I loaded this tune and relogged a short while. Looks like this removed the KR at idle and still no audible knock. However, this update had virtually no change in my poor idle quality.
Does anyone have any advice on how which knock sensor I have, and if my changes make any sense whatsoever? Yes, I'm a newbie at this game! Any and all help is appreciated.
I've spent hours reading through many threads here, all related to knock sensors and settings, etc. but it seems these little devils are a bit of black art - lots of questions, a few answers and many threads that lead nowhere.