Can't get rid of knock

[jsttry]

Gday all, been trying to get rid of one little area of knock for a while now and just can't seem to nail it. At low RPM (1300-1400rpm) at 100% throttle in higher gears I get up to 4deg of knock. Most common way of replicating the problem is driving at 70-80km/hr in 6th and applying 100% throttle. (1400rpm, 100kpa MAP)

I have reduced the high octane table from 15-17deg to 10deg and smoothed the areas around the cell affected and still receiving 4deg. I have logged all forms of spark as shown in the attachment and can't see where the problem may lie. WB AFR's are also included in the screen shot. The screen shot shows that if you feed the power on the knock doesn't occur. Just can't seem the find a cure.

Any help would be really appreciated.

Jay.
-----------------------------------------------------------------
2003 VY SV8 m6, twin spark MAFless, exhaust, CAI, diff.

[GMPX]

It might be worth putting some burst knock in around that area.

Burst knock is designed to take timing out 'before' the engine will possibly knock.
Set burst knock to say 4 - 5 degress between 800 - 2000RPM, then everytime you stab the throttle it will pull timing out briefly, you may not even notice it happening.
You will also need to increase the recovery rate numbers {B6207} so the timing comes back in fast!!.

Cheers,
Ross

[Black02SS]

I am trying to understand a few things.

1) Why is your commanded AFR 14.63 @ a MAP of 101 and TP of 100%
2) How often do you really go 100% TP at 1300rpms?

I am going to go out on a limb and say that if your ve is dialed in for a afr of 12.3 at that point with a commanded afr of 14.63, then the ve is off. I found this out on my car after I got the entire ve dailed in to 13.0 and then changed my Open Loop multiplier back to 14.63.

[jsttry]

It might be worth putting some burst knock in around that area.

Burst knock is designed to take timing out 'before' the engine will possibly knock.
Set burst knock to say 4 - 5 degress between 800 - 2000RPM, then everytime you stab the throttle it will pull timing out briefly, you may not even notice it happening.
You will also need to increase the recovery rate numbers {B6207} so the timing comes back in fast!!.

Cheers,
Ross

What would you define as a fast recovery rate. There is already 5deg burst knock set in table b6212 and a recovery rate of 0.10 for that area.

b6210 has data:
0.137939
0.137939
0.137939
0.137939
0.137939
0.137939
0.153076
0.174072
0.174072
0.174072
0.174072
0.174072
0.174072
0.191895
0.275879
0.344971
0.344971
0.344971
0.344971
0.344971
0.344971

[jsttry]

I am going to go out on a limb and say that if your ve is dialed in for a afr of 12.3 at that point with a commanded afr of 14.63, then the ve is off.

Thanks black02ss. VE table is pretty close with my LTFT within +-4 and all bar one or two cells averaging 0 to -2. Was going to remap using the new autove feature and WB after I got rid of the one little part of knock. Will try to go for a long drive sometime this week though and get the VE table finalised soon.

PS I just remembered why the two AFR's may be out. If its running in PE mode won't the WB show 12.3 but the commanded AFR still be 14.6?

[Black02SS]

If you are running in PE mode, then your commanded AFR should represent what you want at WOT I do belive. The only time your AFR should read anything other then 14.63 is when you are at WOT and your commanded AFR should reflect that as well.

[Tydriver]

Since I am not well versed in the ways of tuning via EFILive (yet...) I will offer another suggestion..

Are you sure that its NOT a hardware issue ?? When I got my '02 Silverado and hooked up EFILive I was bummed to see about 6-8* of KR on it at various throttle settings... Coming from a forced induction background instead of trying to tune it out, I went looking for ignition issues and below is what I found....

This is on a bone stock engine ~53k or so~ each of the 8 plugs was differently gapped as well generally crappy appearing.. I installed 8 new NGKs and the problem went away...

Just something else to consider, in case you havent checked the ignition yet..

Now I just need to move forward and start playing with some tuning on it..

[Draco]

What would you define as a fast recovery rate. There is already 5deg burst knock set in table b6212 and a recovery rate of 0.10 for that area.

b6210 has data:
0.137939
0.137939
0.137939
...


You have some fairly high values in your burst knock delta air mass table. My stock table values approximately 1/3 your listed up to 5200 rpm, at which point my values exceed yours. This means you may never get into burst knock retard (if that is your intention) Here is my stock value list (00 corvette). Maybe since my car runs more timing stock (26-28* total) then an f-body, it is setup to be more sensitive to burst knock retard?

0.040039
0.040039
0.040039
0.041992
0.048096
0.050049
0.050049
0.050049
0.054932
0.060059
0.070068
0.080078
0.100098
0.199951
0.199951
0.199951
0.199951
0.199951
0.199951
0.199951
0.199951

[Delco]

Gday all, been trying to get rid of one little area of knock for a while now and just can't seem to nail it. At low RPM (1300-1400rpm) at 100% throttle in higher gears I get up to 4deg of knock. Most common way of replicating the problem is driving at 70-80km/hr in 6th and applying 100% throttle. (1400rpm, 100kpa MAP)

I have reduced the high octane table from 15-17deg to 10deg and smoothed the areas around the cell affected and still receiving 4deg. I have logged all forms of spark as shown in the attachment and can't see where the problem may lie. WB AFR's are also included in the screen shot. The screen shot shows that if you feed the power on the knock doesn't occur. Just can't seem the find a cure.

Any help would be really appreciated.

Jay.
-----------------------------------------------------------------
2003 VY SV8 m6, twin spark MAFless, exhaust, CAI, diff.

The knock you are seeing is from piston rattle from being at too low a rpm in too high a gear. No amount of timing reduction or fuel adder will stop that from occurring.

[jsttry]

The knock you are seeing is from piston rattle from being at too low a rpm in too high a gear. No amount of timing reduction or fuel adder will stop that from occurring.

Thanks Delco, you and NTAE know my car and the tune the best so I'll take your word on it. :D

Did some more logging today with first a modified VE table and then modified burst knock, still the same problem so I'd say you are probably right.