How can I tell if I have KR ? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 10-13-2004, 02:04 AM   #1
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Default How can I tell if I have KR ?

First off .. I think KR means Knock reduction . Is this right ?
I also assume it means the PCM is removing timing because of spark knock
causing a reduction in power.
I understand I have to use my scantool to check.
What am I looking for ? Is it just the fact that the timing numbers are low ?
I wasn't that concerned about it until I replaced my pulley on the Sc with
a 2.3 inch. Now I'm wondering if i'm getting the full benefit of the additional boost.

If this has been posted in the past I do apologize. I couldn't find it.

JLathem
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Old 10-13-2004, 03:07 AM   #2
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KR stands for Knock Retard and the scantool should have an entry for Knock Retard or look for KS Counter (Knock Sensor counter) ooor you could try to figure it out from your timing measurement.
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Old 10-13-2004, 11:35 AM   #3
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So should the entry in the scan tool for KR be at 0.0 if I'm getting no retard ?

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Old 10-13-2004, 11:38 AM   #4
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yea i am always wondering what KR stood for and how can u tell if u have it or not??
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Old 10-13-2004, 12:32 PM   #5
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Yeah between the KS Counter and Knock Retard values you can determine a bit about the detonation. The KS Counter will go up one value each time there is a detonation, the KR will then display a number such as 2, or 3 or maybe 5. This means its retarding the timing by that amount. The higher the number the harder the detonation. So between the two you can determine how many times you detonated (KS counter) and if you keep your eye on it, or log it, how severe the detonation is (KR).

The best way to do it is if you can record a log and pick out which values to log simply do the KS and Knock Retard values. Start the log and go beat up on it a little. Then you can go back and scroll through looking for the KS counter to go up then look at the corresponding Knock Retard level to determine how severe it is.

Was that helpful?
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Old 10-13-2004, 01:03 PM   #6
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What is the acceptable [or normal] KR? Like if I were to scan tool my car, would I be looking at 0 KR being good? I believe the ECU display'* the KR, because I have a knock sensor.. and the ECU controls the ignition.. but I don't know for sure, the FSM doesn't say anything about it.


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Old 10-13-2004, 01:05 PM   #7
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Something tells me 87-88ish is when the knock sensor came out...it seems like I read that...Anyway a KR of 0 is always best but in hot weather or with a performance pulley and such 1-2deg is generally acceptable.
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Old 10-13-2004, 01:21 PM   #8
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ok, cool. Yes, 87 was the first year for the knock sensor in our bonnie'*. The 86 and lower EFI cars didn't have them.. a rule of thumb, if it has a distributor, it doesn't have any real emissions controls.


-justin
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Old 10-13-2004, 01:36 PM   #9
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Yes that was helpful. I understand it now. That'* the first step. The log book is a great idea. Unfortunately, on my past projects, my method of Knock detection was by ear ...or blown head gaskets. Now I have a computer to help.
I guess the challenge is not to hit a tree while watching the scan tool.

I'm going to start the log this weekend and play around with it. Now that I know what the numbers mean I can get an idea of whats going on. Thanks !

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Old 10-13-2004, 01:39 PM   #10
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I'm glad it was helpful but I think there was a misunderstanding about the log. I meant a lot of scantools have a record feature (log) where you can record it and once you're parked and in a safe place, review it. It'll save you from hitting trees
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