Advise before spark advance tuning needed.

[KMD90]

Hello all, new member here. I'm working on a 2001 Z/28. The attached tune and log is after doing the fuel trim adjustments as advised by HPtuners help section and if y'all think all is well I'd like to add timing. I am leary of doing so at WOT <3,600 RPM as there is already knock evident. This knock has sufficiently lessened since being SD tuned for FT, it used to be audible to the driver at these WOT engine speeds when it was on a stock tune. It had oil in the intake and now has a catch can and several seafoam aerosol top end treatments have been performed to remove carbon and residual oil. The car was fully stock when acquired and I've added a SLP lid, K&N filter, larger MAF ends, and 92MM throttle body. It has also been driven ~300 miles to learn LTFT after the final tune. The engine has already seen A LOT of knock at the 1-2 shifts and on top of second gear pulls as we drove it hard with audible knock for ~ 1 year. If it goes it goes, we have a shop and a 6.2L ready to go in so taking a calculated tuning risk at this point is okay with me I just want to head in a productive direction. Thanks!

2001 Z28 Tune #4 (Final VE).hpt
2001 Z28 Log #4.hpl

[5FDP]

Put a wideband on it to truly dial in the fueling.

The knock could be from running too rich or too lean but you have no idea without a wideband. Commanding 11.44 is a tad rich for a NA motor but you need to confirm if it's actually at or near the commanded afr with your wideband. If it's off, create a AFR or lambda error to dial it back in. LS1's tend to like 12.2 to 12.5 for good power output while being safe.

[jimmyblue]

First you need to determine whether knock is steady
state, or transient. They have different solutions.
Gross mixture will have some effect on transient ping
but the right answer is elsewhere.

Some of the mods you describe are bad news in my
opinion. K&N fouls MAF (lean error). MAF ends also
mess up air mass accuracy and without much to go
on, for tuning that out. Letting LTFT cover it is not
a success strategy (esp. if you have other demons
at work such as long tubes messing up O2 sensor
fidelity / consistency).

Then, you want to have some idea of the space
between steady state ping onset, and MBT point
everywhere on the spark map. This would enable a
"poor boy" spark tweaking like I used to do, where
I'd drive around logging KR and use histo max to
see where KR does and doesn't hit. Where none,
add 1; where hit, subtract 1. A few (or more than
a few) passes through this and you'll have a spark
table that's as edgy as can be. Then subtract your
desired ping-MBT offset (I've seen 2-3 degrees said,
but this was for different motors - do not know if
there is a more general or a more LSx-specific "good
idea" known. I just pulled out 2.'

You want to peel back some fast attack rate and
add to decay rate so the KR is more in-the-moment,
not hanging around obscuring detail (like, whether
KR is steady or transient). 1/2 and 2X worked for me.

Main thing is to have some way of knowing whether
you are making things better or worse. And that, for
spark particularly, is hard to come by other than on
the rollers.

[AutoWiz]

So here's the thing right, your car has 2 o2 sensors and 8 cylinders. there is one o2 sensor that measures each bank or better put one o2 sensor looks at a blended airstream of 4 cylinders. IF, for example, you have a vacuum leak at one of your 17 year old intake gasket o rings then you might well have 1 cylinder lean out to the point of noise. So I am just asking, how many miles are on your ls1 and when was the last time it was serviced properly? as in plugs, wires, intake O-rings, and pcv hoses at least checked? . 2001 is 16 years old. And what kind of 6.2L are you thinking about dropping into your 2001 z28? Just a few months back I tossed a crate ls3/480 into a 2002 z28. I have a build thread for it on this forum right here: https://www.hptuners.com/forum/showt...3-480-2002-z28

...and a more in depth build thread for it here: http://www.digitalcorvettes.com/foru...d.php?t=282746

[KMD90]

Put a wideband on it to truly dial in the fueling.

The knock could be from running too rich or too lean but you have no idea without a wideband. Commanding 11.44 is a tad rich for a NA motor but you need to confirm if it's actually at or near the commanded afr with your wideband. If it's off, create a AFR or lambda error to dial it back in. LS1's tend to like 12.2 to 12.5 for good power output while being safe.

Looks like it's wideband time. Any suggestions? I've been looking at http://thetuningschool.com/product/f...power-adapter/ as I have multiple cars I'd like to tune and am still running a full factory exhaust on most of them.

So here's the thing right, your car has 2 o2 sensors and 8 cylinders. there is one o2 sensor that measures each bank or better put one o2 sensor looks at a blended airstream of 4 cylinders. IF, for example, you have a vacuum leak at one of your 17 year old intake gasket o rings then you might well have 1 cylinder lean out to the point of noise. So I am just asking, how many miles are on your ls1 and when was the last time it was serviced properly? as in plugs, wires, intake O-rings, and pcv hoses at least checked? . 2001 is 16 years old. And what kind of 6.2L are you thinking about dropping into your 2001 z28? Just a few months back I tossed a crate ls3/480 into a 2002 z28. I have a build thread for it on this forum right here: https://www.hptuners.com/forum/showt...3-480-2002-z28

...and a more in depth build thread for it here: http://www.digitalcorvettes.com/foru...d.php?t=282746

It has 110K and has new plugs, wires, and o2 sensors, and I have installed a catch can so I checked the PCV lines then. The intake gaskets have not been checked and the car has always had a kind of odd misfire only at idle. Odd in the sense that sometimes it's there, sometimes not. Is there any way that the o2 sensors can tell me if one bank has a vacuum leak? I ended up with a '10 SS for the 6.2L.

[KMD90]

Put a wideband on it to truly dial in the fueling.

The knock could be from running too rich or too lean but you have no idea without a wideband. Commanding 11.44 is a tad rich for a NA motor but you need to confirm if it's actually at or near the commanded afr with your wideband. If it's off, create a AFR or lambda error to dial it back in. LS1's tend to like 12.2 to 12.5 for good power output while being safe.

Looks like it's wideband time. Any suggestions? I've been looking at http://thetuningschool.com/product/f...power-adapter/ as I have multiple cars I'd like to tune and am still running a full factory exhaust on most of them.

So here's the thing right, your car has 2 o2 sensors and 8 cylinders. there is one o2 sensor that measures each bank or better put one o2 sensor looks at a blended airstream of 4 cylinders. IF, for example, you have a vacuum leak at one of your 17 year old intake gasket o rings then you might well have 1 cylinder lean out to the point of noise. So I am just asking, how many miles are on your ls1 and when was the last time it was serviced properly? as in plugs, wires, intake O-rings, and pcv hoses at least checked? . 2001 is 16 years old. And what kind of 6.2L are you thinking about dropping into your 2001 z28? Just a few months back I tossed a crate ls3/480 into a 2002 z28. I have a build thread for it on this forum right here: https://www.hptuners.com/forum/showt...3-480-2002-z28

...and a more in depth build thread for it here: http://www.digitalcorvettes.com/foru...d.php?t=282746

It has 110K and has new plugs, wires, and o2 sensors, and I have installed a catch can so I checked the PCV lines then. The intake gaskets have not been checked and the car has always had a kind of odd misfire only at idle. Odd in the sense that sometimes it's there, sometimes not. Is there any way that the o2 sensors can tell me if one bank has a vacuum leak? I ended up with a '10 SS for the 6.2L.