This is going to be a long story.
I recently did some data logging on my expedition using an SCT X4 and was getting the following readings for the Knock Retard Index
As you can see, it is quite erratic. Being relatively new to analyzing data from the vehicle I wasn't sure what to think of this. I did some research and from what I've found I know that the higher the number the worse the situation basically. However, from what I read on other forums it seemed that readings should not be this erratic when experiencing knock. In addition, true knock seemed to correlate with engine load, rpms, etc... The readings I was getting seemed to correlate with nothing. As you can see though, there is a pattern and the pattern does change somewhat with RPM, load, etc....but it is still very erratic. The particular sample you see in the screenshot is when I was cruising at about 45 mph (I was using cruise control).
A little background now. I did an engine rebuild over the summer for fun and to learn a little more about the car. In the process I decided to swap out the PI pistons with NPI to increase the compression. You may be thinking "What an idiot" but hey, I like to experiment. I have not yet gotten a custom tune though. I know it is highly recommended with modifications of this type but I just haven't been able to dedicate the time I would like to to it. So, during this particular data logging session I'm running the canned SCT 91 octane tune.
More background info. Since the rebuild, I have put nearly 3000 miles on the truck. In that time, two spark plugs have gone bad on me (Cyl. 2 then Cyl. 1 about 700 mi later) and caused misfires. Here are two pictures of the most recent one I had to replace:
From what I have seen, that is normal wear for a spark plug. The first one I had to replace looked the same. Please let me know if there is anything abnormal about it.
I idled the car for a bit recently and tried listening for any indication of knock. I heard nothing on the driver side and a very slight tap on the passenger. Nothing that would indicate the engine is about to blow up like the data would have me thinking. Plus, I know I have an exhaust leak somewhere near the headers so possibly it is linked to that. I haven't had the time to fix it lately.
Anyways, if you have read this far, thank you. I appreciate it. I tried to include as much info. as I could but I know I'm probably leaving something out. If there is any more information you would like I would be glad to get it for you as soon as I possibly can. Hopefully someone is able to provide a little insight.
I recently did some data logging on my expedition using an SCT X4 and was getting the following readings for the Knock Retard Index
As you can see, it is quite erratic. Being relatively new to analyzing data from the vehicle I wasn't sure what to think of this. I did some research and from what I've found I know that the higher the number the worse the situation basically. However, from what I read on other forums it seemed that readings should not be this erratic when experiencing knock. In addition, true knock seemed to correlate with engine load, rpms, etc... The readings I was getting seemed to correlate with nothing. As you can see though, there is a pattern and the pattern does change somewhat with RPM, load, etc....but it is still very erratic. The particular sample you see in the screenshot is when I was cruising at about 45 mph (I was using cruise control).
A little background now. I did an engine rebuild over the summer for fun and to learn a little more about the car. In the process I decided to swap out the PI pistons with NPI to increase the compression. You may be thinking "What an idiot" but hey, I like to experiment. I have not yet gotten a custom tune though. I know it is highly recommended with modifications of this type but I just haven't been able to dedicate the time I would like to to it. So, during this particular data logging session I'm running the canned SCT 91 octane tune.
More background info. Since the rebuild, I have put nearly 3000 miles on the truck. In that time, two spark plugs have gone bad on me (Cyl. 2 then Cyl. 1 about 700 mi later) and caused misfires. Here are two pictures of the most recent one I had to replace:
From what I have seen, that is normal wear for a spark plug. The first one I had to replace looked the same. Please let me know if there is anything abnormal about it.
I idled the car for a bit recently and tried listening for any indication of knock. I heard nothing on the driver side and a very slight tap on the passenger. Nothing that would indicate the engine is about to blow up like the data would have me thinking. Plus, I know I have an exhaust leak somewhere near the headers so possibly it is linked to that. I haven't had the time to fix it lately.
Anyways, if you have read this far, thank you. I appreciate it. I tried to include as much info. as I could but I know I'm probably leaving something out. If there is any more information you would like I would be glad to get it for you as soon as I possibly can. Hopefully someone is able to provide a little insight.