How likely is KR on lightly modded NA? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 05-05-2008, 04:00 PM   #1
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Default How likely is KR on lightly modded NA?

This has happened twice in the past week. I don't WOT shift much, so it may have been doing it for a while. I'll WOT it through first gear, and it goes to shift into second and it just seems like a power cut, then slowly eased back into power. I was like wtf? I floored it shortly thereafter going sixty and it dropped a gear and hauled ***. With the transmission modulator, it usually shifts pretty firm (I still like a little cushion), and it has chirped the tires shifting into second on tarmac, and these tires are very soft and have amazing grip.

Could this be KR? It feels similar to pulling timing. To me, the transmission feels very strong except for the slight shudder, and I don't know if its in the motor or the trans because it'* been there through out 4 (?) transmissions, but in a different fashion. There have been many threads here on the issue, but none have been able to pinpoint anything.

I'm very lightly modded, I don't think that has anything to do with anything. I don't have a CAI of any type, but I don't think a stock NA would even dream of KR on the stock setup unless something is majorly wrong. I wish I could find someone within 70 mi with a scanner...
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Old 05-05-2008, 04:57 PM   #2
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In my experience, after getting the tuner when I was essentially stock, the stock L36 has significant KR all over the place...especially under heavy load situations like you are talking about.

The factory tunes on these cars are just not that great.

Breathing mods, particularly in the exhaust (DP, PEM or PLOG...I see you already have a hi-flow cat), will reduce that tendency toward heavy load KR.
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Old 05-05-2008, 09:15 PM   #3
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No hi-flow, I figured it wouldn't make a difference.

I have an Intense PCM... wouldn't that have made a difference at all with KR?
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Old 05-05-2008, 09:48 PM   #4
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Whoever moved this thread, sorry, and thanks.
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Old 05-05-2008, 10:15 PM   #5
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I suspect your having false knock. It'* coming from the tranny. Did you install a shift kit? That will help. What hppens is your PCM will pull timing to protect the tranny at the shift points.
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Old 05-05-2008, 11:02 PM   #6
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No shift kit, just modulator. The car is under warranty, and I'm not doing anything noticeable until the warranty is out.
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Old 05-07-2008, 12:12 AM   #7
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just to throw in my experience, i never had any KR on my car stock except for the gutted airbox
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Old 05-07-2008, 12:52 AM   #8
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I haven't seen the bins, but IIRC W-bodies (at least GP'*) come with more WOT spark timing.
So, with a Bonneville it should be harder to get KR.

You should see what kind of max WOT spark advance are you seeing.
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Old 05-07-2008, 01:12 AM   #9
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i think it'* around 17* but i could just be remembering some other random number from the scantool, havent had it out in a while
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Old 05-07-2008, 01:41 AM   #10
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Quote:
Originally Posted by putertopia
No hi-flow, I figured it wouldn't make a difference.

I have an Intense PCM... wouldn't that have made a difference at all with KR?
Sorry, I saw "Magnaflow" in your sig and assumed cat.

If the Intense PCM has advanced timing over stock, that would exacerbate any KR problems you might / would have already had.

Throw a tankful of premium in, run it the same way, and see if the power drop you feel is reduced. This could help determine if there is real KR happening.
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