Tuning my VY V6 Manual for 98 octane

[immortality]

Lots of good info there.

I too have noticed some transient knock.

I really need to get into the VT and see what it likes.

[Wade]

Some more changes from s1 to s2. Theres also changes in the injector multiplier, And even things like the normal & performance upshift pressures or tcc ect. Another thing I noticed is burst knock seems to be active on series 2 vy. But those address's are wrong from what I can tell. Burst knock is actually off for both. So all this gives an indication of tables and things that were changed from the factory, on the same pcm, same engine ect. Just obviously more emissions related with the extra cats ect.

[immortality]

I noticed the Ecotec seems to respond well to richer afr’s as well. But then they become fuel guzzlers. Setting the commanded afr’s to say 12.8 across the board, the engine is way more responsive and a lot more get up and go. But then knock also increases. So I think there is some gains to be had from transient fuelling and then obviously you’d need to look at the main timing maps. I think there’s ae tables but also maf tables. You can do a compare of the vy eco series 1 and 2 tunes and you’ll see the changes they made from the factory. Those changes were obviously emissions related. But yeah I’d love anyone with more experience on those maf tables to come forward.

That's always a conundrum, run it richer and add more timing or slightly leaner and less timing?

Personally I'd go for slight less timing and maybe just richen it up on the transient parts to stop any possible burst knock.

Really need EGT to monitor how much extra heat you are getting from extra timing.

[Wade]

Yeah I’d agree mate . I think there’s already too much timing and overall lean mixtures for emissions reasons. But once you add fuel and head closer to peak torque afr’s you start to get knock. Gotta try find that balance of extra performance vs fuel economy I guess.

[immortality]

On our old VS I thought it was generally on the rich side from the factory. I've not get got a WB on the VT to see where that is.

But yes, I think around peak torque you need to be a little richer and then lean it out a touch heading towards peak power.

I've looked at a lot of dyno tuning print outs and most pro stuff seems to show a similar trend.

[Wade]

I think what’s happening with the vy eco is that with peak torque afr’s low down there’s obviously more cylinder pressure. But because there’s already too much timing it’s inducing more knock. I think with stoich afr’s down low they can get away with that extra timing. And I think that’s exactly what there doing for emissions reasons. But we both know that the eco feels much stronger with richer afr’s. So yeah I definitely feel like there’s gains there. But you’d need to be careful as to not just turn it into a feel guzzler. Try and find that balance I guess.

[Wade]

I think there’s a bit of a debate about holding the wot afr’s flat or leaning/richening ect. If you look at the vy ls1 285kw tune pretty sure it holds it flat. Not sure if there’s offset influencing it though. It’s been a minute. But then if you look at the vz ls1 tune it does change.

[Wade]

I remember ages ago logging maf and afr’s after stomping the throttle, and remember there was a delay in maf readings. Just wondering if those maf tables I shared earlier have something to do with that. Probably the reason why the map based ecm’s feel more responsive on the eco? There’s maf vs coolant, tps and rpm ect ect. And no one seems to talk about them. Even a google search doesn’t bring up much results.

[Wade]

If you look at the scalers before those maf tables there related to transient fuel. So I find that very interesting.

[immortality]

I think what’s happening with the vy eco is that with peak torque afr’s low down there’s obviously more cylinder pressure. But because there’s already too much timing it’s inducing more knock. I think with stoich afr’s down low they can get away with that extra timing. And I think that’s exactly what there doing for emissions reasons. But we both know that the eco feels much stronger with richer afr’s. So yeah I definitely feel like there’s gains there. But you’d need to be careful as to not just turn it into a feel guzzler. Try and find that balance I guess.

I think that is also a trait of MAF based EFI tuning. Run everything at stoich until you hit PE and then it's throw everything at it.

I do think though by VY Holden really had it figured out. I remember been in a friends VY when we still had our old VS and it seemed worlds apart.