Knock Counts
Thread Starter
Drifting
Joined: Jul 2014
Posts: 1,426
Likes: 46
From: Lynchburg, VA
Knock Counts
I just got ALDLDroid and a Bluetooth ALDL adapter for my '90 6-speed coupe, so I've been looking at the ECU data.
I noticed to my surprise that I am getting knock counts. I have never heard spark knock in person, but nothing about my engine sounds abnormal to me.
The knock counts start out at 0 and climbs as the engine runs. By the end of a short test drive today it had risen to 8 counts. One data log from the other day shows it getting up to 28.
When the computer detects knock, it is supposed to retard the timing accordingly, correct? The logs show that the knock retard spikes when the knock count rises at all (or sometimes immediately before that happens) but then drops back down to 0.
I filled it with 91 octane just in case (I had been running 89) but it's still an issue. Any ideas?
I noticed to my surprise that I am getting knock counts. I have never heard spark knock in person, but nothing about my engine sounds abnormal to me.
The knock counts start out at 0 and climbs as the engine runs. By the end of a short test drive today it had risen to 8 counts. One data log from the other day shows it getting up to 28.
When the computer detects knock, it is supposed to retard the timing accordingly, correct? The logs show that the knock retard spikes when the knock count rises at all (or sometimes immediately before that happens) but then drops back down to 0.
I filled it with 91 octane just in case (I had been running 89) but it's still an issue. Any ideas?
Thread Starter
Drifting
Joined: Jul 2014
Posts: 1,426
Likes: 46
From: Lynchburg, VA
Any idea why the ECU pulled timing each time the knock count rose? Is that just normal programming?
Here's a picture of the datalog so you can see what I mean. Blue is knock retard and yellow is knock count.
Thread Starter
Drifting
Joined: Jul 2014
Posts: 1,426
Likes: 46
From: Lynchburg, VA
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
The computer is always trying trying to get to its programmed spark timing, (For max performance) if there is no spark retard detected the computer will add in any spark that was pulled before. As far as the engine is concerned the timing is pulled out very fast and added back in slowly.
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