2008 G8 GT knock retard

[Niemer]

First let me say that I'm very new to all of this and I'm doing my best to learn as much as I can.

I've noticed a lot of knock retard, up to 7.5*, in my logs that I'm wondering/concerned about. I'm concentrating my efforts on the transmission at the moment since I don't have a wideband yet, but I did do some partial throttle MAF frequency tuning. Most of my changes have been to the shift times, inertias, pressures, and TCC. But, I have played with the shift torque factor and adder modifier table, which as I understand can and do modify timing pulls during shifts.

What I'm wondering is, will the knock retard that I'm seeing do any damage or is it just a loss of performance at this time before I can start tuning spark and fuel?

The 7-20 log is stock with knock retard up to 6.5* in a few seemingly random places, the other log is with my current tune, that is also attached, and most of the retard is during the 3 WOT runs. I have determined that the KR blips in the v1.3 log have something to do with DOD as it cycles on or off around those points.

[glanzergtx]

When tuning its better to have the DOD disabled to get everything dialed in. Then enable it when finishing up with the tune.

[Niemer]

Thanks for the info, I'll get a log with it off to see what happens.

[jonnycatz]

Your Power Enrich enrichment rate is extremely low. You are never actually getting the commanded PE AFR. Just very, very slowly moving towards it. Try changing enrichment rate in "power enrich" tab under fuel tab to 1.3 instead of 0.01 that it currently is at. I would also change the Delay RPM in the same area to zero, so you do not have to be above 5000 rpm to enter PE mode. The most power is supposedly made at about 12.7 to 1 AFR. Therefore, you would want to change your EQ Ratio vs. RPM table to about 1.15 across the table to begin, and see how knock retard goes. You can slightly increase the ratio above 1.15 around the rpm range where any knock occurs to compensate.

[BigDaddyCool]

holy smokes, your knock retard is worrying dude.

generally speaking for the most part it looks ok, just need to bring on pe in those area's.

drop your Throttle in PE down to 30%, set to 0.1000 for enrichment rate........ and then see how knocking goes without any other changes.

It all goes well, 'then' work on ATR

PS. Not sure about G8's, but if your 'throttle' wasn't set to 100% response....... if you did that, you need to bring on fuel just as fast to match

[Niemer]

The PE enrichment rate was stock, I've changed it to 1 and set the delay and enable rpm to 0, left the EQ ratio alone for now. Just got my wideband installed so I'll actually be able to see what is going on.

Thanks for the tips, guys.

[Niemer]

Still seeing a bit during normal driving but down to a max of 2.5*. Any ideas on what might be causing this and what to do about it?

I have added headers and a wideband since the first post, fyi.

[bluegoat06]

Your WB is displaying 15-16 afr during part throttle. since you're doing PT in OL, bring those values down to 14.7, meaning you still have some work to do in the MAf up to 7200hz. you haven't touched the 7200hz and above cells yet.

The 6* at WOT in in your initial logs, that's stock timing, are you pumping 91 octane ?

[IDRIVEAG8GT]

Headers are what's causing it FYI. You haven't touched your knock sensitivity rate for the additional noise and vibration caused by your LT's, since they do run right next to the knock sensors. Take around 5-10% off your knock sensitivity, Speed up the knock recovery rate just a tad, and then disable BKR so you can dial in your timing where you actually need it.

[IDRIVEAG8GT]

Also here's how you properly set up PE:

[LazMan]

Agree 100% with IDriveAG8GT !!!

Also, if you have E10 in your area, set your AFR to match.

Fuel -> General -> Stoich AFR -> 14.222656 across the board.
(about E08, close average for areas with E-10)

[bluegoat06]

Huh ?
Wouldn't be better to bring fueling down to 14.7 instead of leaving him with the 15-16afr he's got right now in OL ? Lol, what are we recommending ?

What do you guys mean the problem is with LT's?, then telling him to mess with knock sensors sensitivity? , Also, does he wants PE at what 1400-1600 rpm at .36-.52 g/cyl... you have to be kidding, Lol, what is this, touch the pedal with your finger and reach PE ? FIX PT fueling and most of that KR should go away. can't be any easier.

And 14.22 afr as stoich point in southern cali for example is a big fail, our gas MAY contain E10, most gas stations around here sell E5 or E7. better medium point would be 14.5 and let the O2's handle the rest. Learned the hard way, so just trying to save time

[IDRIVEAG8GT]

Huh ?
Wouldn't be better to bring fueling down to 14.7 instead of leaving him with the 15-16afr he's got right now in OL ? Lol, what are we recommending ?

What do you guys mean the problem is with LT's?, then telling him to mess with knock sensors sensitivity? , Also, does he wants PE at what 1400-1600 rpm at .36-.52 g/cyl... you have to be kidding, Lol, what is this, touch the pedal with your finger and reach PE ? FIX PT fueling and most of that KR should go away. can't be any easier.

And 14.22 afr as stoich point in southern cali for example is a big fail, our gas MAY contain E10, most gas stations around here sell E5 or E7. better medium point would be 14.5 and let the O2's handle the rest. Learned the hard way, so just trying to save time

MAP enable is the determining factor of PE my friend. It makes them get off the line. Should have no issue with fuel economy setting it up how I listed it.

And yes it really is what's causing it unless youd rather have him wrap heat shielding around the knock sensors to give some sort of vibration resistance to the LT's.

Agreed the lean note is causing part of the issue but not all of it.

Try my PE method for yourself.