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Help with KR

H

Howling Mad

New member
Now I know what you're thinking "not another one of these" but hear me out. My current setup is:
Gen V
Ported blower
Ported LIM
Ported heads
Custom cam (somewhat of a hybrid kind of sits between a vs and an zzp xp)
Headers
N* throttle body
60 injectors
DW 300 pump
Hotwire kit
Built transmissions
E85
Poly mounts
For the past year I've been running a 2.8 pulley and it's been awesome then a few days ago I started noticing some random kr. It has really been all over the place sometimes on tip in, sometimes at wot, sometimes part throttle, traction control on, traction control off, 30mph roll, dig, whatever. But its completely random. I can do 10 pulls and have 0.1 blips at tip in and nothing more, I can do 10 pulls and have 1-9 degrees of knock on all of them. I've went to bigger pulleys, no change (currently on a 3.8 and it's still doing it). I've searched for anything that could be touching together and cant find anything, I've changed fuel filter, wires and plugs (plugs showed no signs of detonation) still nothing. There are no misfires, afr has stayed consistent, no bottom end noise, nothing. So I'm wondering what are some other things I could check. Possibly a bad sensor (I've never had one go bad but who knows), noise from transmission maybe, supercharger coupler going bad (it doesn't sound any different from normal and the coupler was replaced less than 10,000 miles ago)? I'm really open to all suggestions at this point
 


scan your 02 sensor, it should be reading 930 MV ish give or take and lock in there wot. if it drops the fueling goes off and you get knock. lots of it.

had the same issue, was all set then it started getting kr for no reason, even dropped timing and it still knocked. finally noticed the o2 was dropping off to 0.79 wot.
 
He clearly said the air fuel ratio is not changing so why would the o2 sensor mean anything here?

C'mon brah, don't skim read.

I wish these computer were more advanced and we could more with changes to timing, knock settings and the like but we can't. It's plausible even with brand new AC delco knock sensors that the issue could still show up. With how tight everything is packed in there, if one thing is causing a vibration it could be getting pick up by the sensors but yet be almost impossible to figure out.
 
We should also point out that 930 mv and 790 mv could actually be the same afr.

I've had axles cause false kr before. The road where I was testing had some bumps that caused the suspension to flex, and this always happened at the same rpm and same gear. It took me awhile to figure that one out.
 
Fivefingerdeathpunch said:
He clearly said the air fuel ratio is not changing so why would the o2 sensor mean anything here?

C'mon brah, don't skim read.

I wish these computer were more advanced and we could more with changes to timing, knock settings and the like but we can't. It's plausible even with brand new AC delco knock sensors that the issue could still show up. With how tight everything is packed in there, if one thing is causing a vibration it could be getting pick up by the sensors but yet be almost impossible to figure out.
Click to expand...

my wb also never leaned out........why i say scan that o2 sensor.
 


it changed fueling enough to cause kr. new o2 fixed my issue. a o2 reading 0.79 is bad. it would spike to 930's then drop during the pass. and lock in there very low.

scanning the o2 is free. its worth checking out.
 
Scottydoggs said:
scan your 02 sensor, it should be reading 930 MV ish give or take and lock in there wot. if it drops the fueling goes off and you get knock. lots of it.

had the same issue, was all set then it started getting kr for no reason, even dropped timing and it still knocked. finally noticed the o2 was dropping off to 0.79 wot.
Click to expand...

Did your plugs show any signs of detonation when this was occurring?
 
Does sound like a fueling issue. Check for vac or exhaust leaks? Leak around 02 sensor? MAF maybe needs cleaned or replaced? Are you tuning this or just scanning with an aero gauge or torque?
 
bandook said:
Does sound like a fueling issue. Check for vac or exhaust leaks? Leak around 02 sensor? MAF maybe needs cleaned or replaced? Are you tuning this or just scanning with an aero gauge or torque?
Click to expand...

Checked for vacuum and exhaust leaks but couldn't find anything. I did clean the MAF sensor but I didn't see any thing odd in the scans with hp tuners. I only got kr on a few scans but nothing looked odd on it, no lean spikes or anything. Its weird lol
 


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