My 05' 6-speed has what seems like extremly low ignition timing. Basically it peaks at 19.5, then drops down to 17.5 for most of the higher rpm range.

An 00' F-body has stock timing in the mid-high 20's, and of course, my car's timing is in the high 20's to low 30's.

Anybody want to share their number, especially if done by a tuner or other aftermarket setup

 

I noted similar timing issues but the overall spark advance table isnt indicative of what the net timing is. The factory tune seems to have near maximized the timing and it is more and issue of tuning the timing curve to your specific mods. I have 21 degrees up top now but with my high compression, I couldn't add anything in most low rpm places.

In most rpm ranges it was more of adding 3 degrees everywhere and then pulling back 2 where I saw KR. It didnt take but 2 iterations to find that the effect was maximized already. Under 5K, 60% of the table accepted 1 degree, 20% took 2 degrees. 10% was already there and the last 10% was already too much. I think the factory maximized the high octane base spark and did the safety tuning by the other tables that pull timing by ECT, IAT, Bar pressure and TQ management tables. Those are the locations that you change by limiting what they take out. I noticed quite a difference.

As posted befroe by many guys who have tuned on a dyno, maximizing timing doesnt nec. mean you get more power from it. Although you can get the table to accept more, there is a safety margin that must be factored in. This time of year is a cool/timing friendly ambient condition. In the summer, the tune may be a little too much if you dont leave in some timing correction for temp. increases.

 

it just seems really odd to me. I have several tunes from LS1 engines where the timing peaked around 28-29, then held close to it from 4800rpm to redline.

Seems like a big jump from 17.5 (19.5 peak,but only one cell) stock to 28-29. These tunes are supposedly for street cars, but who knows, they might have been set up for high octane fuel.

 

You are talking about the high rpm spark table and that is not what the car actually runs timing wise as it was with the C5. If you datalog the timing up there it may be higher. I assume there is timing being added from other tables where it wasnt with the LS1 PCM. Just because you enter 21 degrees or so doesnt mean it isnt seeing 26-28. Log it. The HPtuners scans show the net timing. I dont know what software you are using to scan.

 

I scan with Autotap, and tune with LS2edit, and I just noticed the phenomenon you mention. Any idea how to actually set Net timing, or how it is "added" to the spark tables?? I posted some questions on the LS1edit mailing list a while back, and there aren't enough LS2edit users yet to know.

 

My best guess is that the high octane spark advance table is better viewed as a timing curve table rather than setting peak timing. The net is still composed of this table so adding here makes it into the overall values anyway.

Logging is the only way to see where you are. I was misled by the need for the tables being maxed out like the C5's but this simply led to less timing since the happy pacm yanks out a lot in proportion to KR.

I suspect a lot of tuners just assumed the timing similarities and did a lot of mail order tunes with too much timing relying of the pcm to pull it where needed.

As a side note, James from RWTD states that he sees little room for improvement on a stock GTO also so it isnt a C6 issue. His theory is that the factory maxed out this table and relies on the timing pull where the PCM needs it.

It also seems to take a lot longer (than C5) with the C6 to return the agreesive timing pulls to normal after KR is detected so you have to address the rate and decay of that in the tune.

 

Dave, while data logging if you nail the gas at idle while standing still, do you see any knock retard burst or while engaging gears at all especially in first? I cant tell if its hearing the clutch chatter.

 

What I find weird is the LS2 internal design is very similar to the LS1/6. With similar combustion chamber design and piston design one would think that the timing is going to be close to the LS1/6 tables.

 

I think the ultimate timing needs are the same (ls1 ls2 ls6), it's just the PCM that is totally different.

I can't log retard right now. I can log total timing, but Autotap won't do enhanced features yet for 05's and up

 

Yes Phil, as I said on the phone while you were laughing at me, was that the base spark table is only part of the story. What is in the base table is apparently added to during a run and there are adders that go into the final amount of timing that gets run. If you datalog it runs higher amounts of timing than you set in the base spark table. So it isnt just 19,20,21 degrees. It actually runs much higher amounts.

When you are ready to stop playing with satan's daily driver there, I will head down with a real car to show you the deal on the C6.

 

Here's a log taken last night, this is the stock tune. I got a max of 25* timing.

RPM O2 1 O2 2 SPARK KNOCK
3135 0.85 0.85 22.5 0
3434 0.86 0.85 22.5 0
3648 0.86 0.86 22.5 0
3826 0.86 0.86 21.5 0
3972 0.86 0.86 21.0 0
4076 0.87 0.86 21.0 0
4340 0.86 0.87 20.5 0
4573 0.87 0.86 21.0 0
4857 0.86 0.87 21.5 0
5095 0.86 0.88 22.0 0
5208 0.87 0.88 23.0 0
5419 0.87 0.88 24.0 0
5548 0.87 0.88 25.0 0
5682 0.87 0.88 25.0 0
5787 0.87 0.86 25.0 0
5933 0.86 0.86 25.0 0
6087 0.86 0.87 25.0 0
6209 0.86 0.87 24.0 0
6378 0.86 0.86 23.0 0
6500 0.86 0.87 22.5 0

 

I'm seeing the same type of timing issues with my car. Installed LPE intake, LGM headers, and a mail order tune. My high octane table is set at 23 degrees, but I'm seeing up to 4.5 degrees of KR at WOT in 4th gear on the road, and the AFR is at 12.9 while it's happening. Looks like I may wind up back near stock timing values. 93 octane fuel.

 

This is all great info! Like David, I can't log Knock retard with my cable/software setup right now, but I can log the total spark advance, which should be almost as useful IF I can decipher the various factors and where the spark "should" be...which should give me the knock retard indirectly.

I have a Vararam, LG Street LT setup, Maf screen delete, borla stingers, and TB bypass and the car feels slower (though the fuel trims have been adjusted thru SD tuning). I'm sure I'm probably getting some knock but I have no way to tell!

Any ideas?

 

Do you have aftermarket intake or exhaust stuff on your car? Those O2 readings look a little lean for WOT.....of course they're not equal to a wideband but I have heard that you want to be closer to .900 rather than .860....usually less than .880 is lean....

 

Silver05GTO,

Are those readings from a predator ?

Bulldog,

I have a C6 with kooks headers and I run right at .86 - .87 and I was told that is right around 12.5-12.7 on the wideband.