PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

KR going off under load. is this normal?

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Old Jan 17, 2012 | 08:03 AM
  #1  
VerdeZ28's Avatar
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From: Pembroke pines FL
Default KR going off under load. is this normal?

KR-which i assume means knock retard, is going off under load. i saw this several times while running VCM scanner. I would like to know why is this happening. in my car it went up as much as 10* several times. on my bros mostly stock 02 Z28 it went off only once about 4*.

if i had to guess it could be since i basically have full bolt ons and never really tuned for it, could it be somewhat leaning out?
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Old Jan 17, 2012 | 10:30 AM
  #2  
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It's not unreasonable, long timing or short fuel (or a
false knock). Don't focus on how much, but rather
"why?". KR will overshoot for safety with stock settings.
Which makes debug a little more difficult (if you are
wanting to tune it up to the edge).

Look for an O2 voltage dip immediately preceding KR
as an indicator of short fueling; if it's fat but pinging
then timing wants pulled back; if it's always at a
certain RPM then consider motor noises (rocker minus
needles, bad / weak spring, etc.) as a possibility for
false KR. Or if you can hear anything banging.
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Old Jan 17, 2012 | 06:05 PM
  #3  
VerdeZ28's Avatar
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KR peaked at 11.6* and just before this happened O2 sensors were at about 130-140mV. is this what you are talking about

im also noticing that KR goes up to around 3.5-4 at around 4500 rpm consistantly so that may be due to engine noise but the 11.6 KR happened at 2300rpm
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Old Jan 17, 2012 | 06:06 PM
  #4  
VerdeZ28's Avatar
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could it be that the hypertech tune is calling for too much timing advance in this range?
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Old Jan 18, 2012 | 06:18 PM
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Default

Most HyperTech tunes I've seen add some timing @wot and right at it, nothing excessive the rest of the table is stock along with PE.
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