SladeX

I just picked up a C6 stock car. LT3 trim not that it matters. Has around 55k on the clock. Stock wires/plugs (will do tune up later to see if this helps).

I'm data logging the car to guage the health of the engine and found knock retard happening while I'm cruising. I'll be trying to hold 70mph give or take and as I make fine adjustments in throttle ie I see I blip the throttle and it triggers knock retard of -6 but not every time I do, just sometimes...

Any thoughts on this? I'm at work, log to be posted later today...

edit: KR is only at WOT
TLR version:
KR@ cruise/WOT
Did plug change (tested TR5 and TR6)
Did wire change Stock/Granatelli/MSD
Did seafoam 2x (seemed to help a lot after 2nd treatment, cruise is cleaned up)
WOT still has issues
Pinging is audible @ WOT! Decided not to desensitize knock sensors due to me being able to hear it. Burst is disabled and Knock attack is lessened by 50%
Noted stock tune has a very rich PE 11.87 commanded @ 4700 rpm, 12.1 avg everywhere else in the mid-upper, see mostly stock tune posted later in thread)

JetMech442

iTrader: (1)

I only know a little about ls1b ecms so far, but since this is related to throttle adjustments, could it be related to delta air mass values? I know the ecm will pull timing in anticipation of knock when quick throttle changes are made.

SladeX

I've been reading up on the HP Tuners website and I've been seeing this is not an isolated thing. WOT runs show no KR, just cruise. The oddball part is this happens when trying to maintain a constant speed. I personally don't notice it unless I'm staring at the HUD where I see a minor drop in speed despite it being flat then promptly correcting itself if I don't modulate the throttle. It's not me moving it if the throttle is blipping. I notice that in the log when it does do it, there is a spike in MAP sensor reading like it blipped the throttle despite no tb movement in the log... I got distracted yesterday so I will try to get the log up today.

SladeX

Log uploaded of my cruise KR. It's weird. Throttle and speed are constant, but KR happens randomly. I've done a tuneup on it, new plugs and wires so I will log it tomorrow to see how it affects this.

SladeX

Did tune up, new tr5 plugs gapped to 0.040, new granatelli wires. Cruise KR is all but gone, but still have KR at wot, will play with PE delay etc to see if I can get it rich quicker. Will also clean off MAF.

thunderstruck507

iTrader: (18)

Do those newer PCMs have burst knock and if so have you tuned it out?

SladeX

There is burst knock settings. I've been doing more logging and I'm getting knock all over. I've tried a seafoam on it to see if it will help. More loggging to do. This is a stock car. It shouldn't be knocking around like this. I feel like I'm being robbed of my power.

Any c6 ls2 owners log seeing this crap?

ctd

iTrader: (1)

Yes & I fought it to death. On the dyno while battling KR I simply switch to TR6 plugs. I did a thread on CF a long while back detailing the change.

SladeX

thread title? what did you learn about it?

I've managed to calm down the knock on cruise, still getting a bit here and there, but at least I can now drive with 0's across most of the table. WOT still triggers 2-3 degrees of KR so I've been staying out of it. Fake or not, what is real is that it is pulling timing. I've swapped to TR6 plugs now and I've gone 400 miles on the TR6 so I will see if it has signs of detonation on any of the plugs. So far all I've done is seafoam and some driving. It had a fresh oil change prior to me taking ownership so oil wise, its good.

Tune is still stock. Checking plugs this morning to make sure there is no signs of detonation. I will try zeroing bust knock, and if that doesn't work, I will de-sensitize the sensors.

ctd

iTrader: (1)

I picked the tip up from a HPT forum member.

http://www.hptuners.com/forum/showth...plugs-dyno-run

SladeX

Still got KR.

This is a stock 05 LS2 vette.

Running 91 octane.
Tried running octane booster: no effect
Removed burst knock by zeroing out tables: no effect
Tried running lower timing (23 stock, tried 17): no effect
Plugs changed to TR6IX: no effect
Tried Granatelli wires, MSD and stocks: no effect
De-sensitized knock sensors to 11 all around: no effect
Checked fuel pressure: 60 psi idle, shut off, drops to 50 psi but holds. Doesn't seem like a leak. No way for me to check while driving but seems ok...

Checked plugs: TR6IX shows no detonation, is a light tan-gray color, been on car now 600 miles. No dark specs on it, just clean plugs.

Ran seafoam cleaner. Seemed to clear out low end knock retard, but still getting on high gear accel (ie speeding up in 5th/6th) or WOT, pulls as much as 3-4 degrees.

Ideas?

edit: Can a dying alternator cause KR? I noticed as I was picking up the gf from work I had it swing from 11.6 to 13.2v

SladeX

Scratch the alternator bit. The low idle is giving the alternator fits when everything is on a/c, lights etc does 11.9-12.2 v at idle, but it recovers once driving. Will monitor it in traffic. Bumped idle to 750. Seems ok, staying above 13 v

SladeX

Ok so did a 2nd seafoam and cruise timing seems to have stabilized. WOT still shows some KR. I've halved the knock attack and zeroed out the burst knock. Log shows no BK but KR is real and I hear it when going WOT (like little metallic pings of popcorn, just a bit)

Now recall other than the burst knock and knock attack, its basically a stock tune.

I've noticed in the area where knock is happening, the commanded PE is pretty rich, dipping to 11.9 I think where knock is strongest. I think in my early 98 tune days I commanded a 1.3 and got some knock out of it too in much the same manner. I kept backing down on the PE until I got it right at the time (I did not know any better about MAF tuning and used PE to dial WOT only)

Anyone think that the WOT knock is really a too rich condition? I'm tempted to lean it out a bit to see if it cures my KR. If you look at the log and the tune, the worst knock coincides with the richest commanding of PE. I've done a test run with about 5% more on the MAF table in case lean was the issue on the high portion 8k up and it worsened the KR...