LS1 gto that doesn't like timing??

[kjhallex]

I'm tuning a LS1 gto, A4, 3000 stall, CAI, and Cam specs: 228 duration .588 lift 112+4 lsa. Plugs are tr5's gaped at .060

This car does not like timing at all and I know I have to be missing something. This is the last log with the least amount of KR I got it down to. I really don't think it's bad gas because I run the same in my pro-charged gto with no problems. Here's a log let me know what you guys think.

Thanks in advance!

[04SilveradoMykk]

Just a quick glance of the log and tune and I think I'm seeing burst knock. Try to zero the burst knock tables and see if that helps.

[kjhallex]

Completely missed that, I should of been logging it. I will try it and report back.

Thanks!

[Travis01gt]

Try TR55 Plugs or Even TR6's if you can't get rid of the spark knock.

[Rinkrat456]

Try to zero the burst knock tables and see if that helps.

The burst knock threshold table is a set limiter table - IIRC it should be raised not zero'd out. I thought lowering that table would make it easier to enter burst knock retard.


You would want to desensitize (or zero out) the vs ERT. vs ECT. table I believe.

[04SilveradoMykk]

The burst knock threshold table is a set limiter table - IIRC it should be raised not zero'd out. I thought lowering that table would make it easier to enter burst knock retard.


You would want to desensitize (or zero out) the vs ERT. vs ECT. table I believe.

You are correct regarding the Burst Knock>Enable Delta Cyl Air. To eliminate burst knock you'd want to zero out the Mult vs RPM & ERT vs ECT, I was referring to the latter.

I too would recommend TR6 plugs for any engine producing more HP than stock

[sarg]

Can burst knock cause a vehicle to switch to the low octane table? I have started playing with a 2007 Trailblazer SS that is pretty much stock and it appears as though it is running off the low octane spark map. The only real KR I see is low rpm sudden throttle changes. The only mod on this vehicle is a modified inlet and filter. The MAF tube is still factory.

[jimmyblue]

Burst knock retard is a predictive "cover-up" spark pull
on transient throttle opening. Knock retard is reactive
to knock detects. Early trucks have stupid low BK thresholds.
I would expect cars to not, but have never looked at a
Goat.

If you have a lean dip on opening throttle your VE table at
that point is perhaps over-lean. But if it's right in steady
state then you may prefer to work with the transient throttle
stuff (see old threads about "accelerator pump", which will
probably confuse you before they help you). The VE table
traversal is time-filtered and the sensors are all slow, MAF
being the slowest so ignored on purpose, but if your VE
table is bogus-lean you will definitely see a bad lean dip
on tip-in. This is what BK is trying to cover up by pulling
spark. Question is, how long before mixture gets right and
how much spark really wants pulled, for how long. Answer
if fueling stays right, is "none". Raising the delta CylAir
threshold can keep it from messing or only on extreme
throttle-mash, you just have to get at the delta air
which is not an available PID, you have to get that from
Excel by taking the difference and divide by the frame
rate.

[sarg]

I have not had a chance to dial in the VE tables yet. I just found out about a program that makes a single "virtual ve" table out of the 4 tables the trailblazer SS has from the factory. That is the next step in trying to eliminate it. AFR appears to follow the factory commanded fuel pretty close but is leaner on tip in. I am hoping that modifying the VE tables will help this. I am also going to richen up from 13 (factory) to around 12.5 in those areas.

[kjhallex]

Tried the BK changes and that wasn't it. I also logged bk and it's not picking any up. I'm going to get him to switch to Tr6 plugs and report back.

Thanks for the help!

[domestic rice]

Tried the BK changes and that wasn't it. I also logged bk and it's not picking any up. I'm going to get him to switch to Tr6 plugs and report back.

Thanks for the help!

So did those plugs help?

[domestic rice]

Well I tried the swap anyway. All the low end knock is GONE! TR6 worked for me!