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L36 kr

N

Nchristopherson

New member
I've done some searching, but can't really find anything that gives in-depth information about KR on the L36. I have a couple of questions based on my own observations from driving my car.

1) What is "normal" KR for the N/A 3800? I know some say up to 7* is normal for the S/C version, but I am getting up to 11* at times. That seems awfully high.

2) What are the main causes for KR in a stock engine that normally runs KR free? So like, lean conditions, plugged cat, etc.

3) Is catastrophic engine damage plausible for a stock engine that is running high in KR? I know KR is evil and should be reduced at all costs, but I would expect GM would have some sort of protection to prevent your engine form detonating without you changing anything.
 


Oh, I should also mention that I tried running premium in my car, but that didn't seem to help. Iirc, it still shot up to around 9*. As the car gets warmer, the KR seems to go up. So a WOT pull right after getting it up to temps where KR is scanning, I see maybe 2-4*. On the on ramp it will get up to 7*. Cruising on the highway and getting into it causes the huge spikes in KR. Could a transmission cause that much noise at the same harmonic frequency to fool the pcm?
 
All L36s have lots of KR from the factory. Mine had 6+ almost the entire time I was over 50% throttle when it was stock. KR doesn't hurt the NA motors, it's just inefficient.
 
I'm N/A too and see 6-12* of KR I blame my motor mounts mainly because at the top of 2nd I have basically no KR at the shift. I also see some false knock from the car going into 3rd and 3rd lockup i believe it is. Spikes up to like 5* or so.

Running 91+ killed a lot of part throttle knock when cruising around at like 55 but WOT it would spike back up to 9-12 then gradually go down towards the top of 2nd. But like nos4blood said it won't hurt anything.
 


When you change fueling and timing for the turbo set up, the knock will go away. I promise that you don't have to worry about the L36's factory knock. Mine all went away with just a tune.
 
Just deleting the U-bend, doing a FULL tune up, and getting a solid PCM tune in the car will probably take care of all of it...if the tune-up with new mounts and such wouldn't already.

My '98 GT had 7~* of KR at the shift at the top of second. I did an L26 UIM, ported GTP TB, GTP injectors, ported manifolds/exhaust work, L76 springs and a custom in car tune with mine. No knock and was running assloads of timing and if I remember right it was pretty lean. Ran door to door with a stock GTP.

As for the answer to your questions...7* on a blower car is MUCH worse than 11* on an N/A car. To test it, try throwing some high octane gas in it on the next fill up. If the KR drops, then you need to just open her up a little...new converter/high flow (or getting rid of the cat all together) and deleting the U-Bend will do plenty flow wise. If the higher octane doesn't fix the KR or lower it at all...then I'd look elsewhere. Failing mounts, vac leaks, LIM gaskets, warped plastic intake manifold...needs a tune-up like I stated, etc.

Start there.
 
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