Safc Tune, Timing Or Piston Leak?

[ak_stylez]

Hey people,

My r33 s2 has the following mods:

pod with box

3" turbo back exhaust

stock turbo @ 10psi

r34 gtt smic

SAFC

I got the car dyno tuned yesterday and it made 176kw. My tuner said it's still running fairly rich. He was unable to lean it out further as it started pinging. He thinks a possible cause for this is there may be oil in the cylinder (perhaps from a piston leak - hopefully that's not the case). Another possibility is that my stock ecu is advancing the timing too much causing it to ping, in which case i need to get a power fc (or a near non-existent sitc). I think the AFR is around 9 (very rich), and the safc shows a correction of only -2 across much of the high throttle (60%) and 0 across the entire low throttle (30%).

the pulley thing at the front of the engine (for manual timing adjustment) is set at "10", (whatever that means). This was set by my previous workshop. Current tuner did not change it, saying it shouldn't be any lower than that (down from 14 standard?).

First of all, can i just get a rough idea if that looks like a correct safc tune? i don't know but i was kind of expecting a little more variation, not just a flat -2 on high and a flat 0 on low. Also, how does the high/low throttle tune work? one set of corrections for above 60% and another set for above 30%? what about below 30? no correction?

secondly, shouldn't all series 2 r33 ecu's be the same? are some known to have more aggressive timing than others?

and finally, is 176 reasonable for my level of mods? i was expecting something closer to 190, but the car is still running very rich, so that sort of explains it.

Also, i *sometimes* feel a bit of a flat spot, which is followed by a slightly weaker pull. This may or may not be related to the above issues. However this is not evident on the dyno graph.

Thanks for your time, guys.

Edited September 27, 2007 by ak_stylez

[ak_stylez]

Anyone able to shed some light on these questions? I'm not doing anything new, so should be plenty of people with the answers I need. I did search and couldn't find anything.

Thanks!

[RPR33]

have you got a dyno graph? the power is not that low 176rwkw on 10psi sounds good

[ak_stylez]

yeah i do but no scanner.

Boost jumps up to 9 psi at about 2500 rpm, then creeps up to 10 by 4000rpm where its fairly steady til red line.

the power curve is fairly straight with a few bumps here and there and max power is just after 6 grand.

does that help??

[QWK32]

for starters the pulley on the front of you car for the manual timing, or the CAS should be set at 15 degrees, 10 is to low.

the throttle set points with your settings of low 30% and high 60% are: low throttle map is 0% to 30%, and high throttle map is 60% to 100%. everything between 30% and 60% throttle are just interpolated. the tune that you are describing doesn't sound like a real tune at all. -2% of the high map is bugger all and with your mods you probably don't need to trim or add anything on the low throttle map. the std ecu's like to rich out under full throttle and boost.

i'd say get your base timing set to the correct setting, 15 degrees, and you should be able to trim much more off the high map without getting pinging.

[ak_stylez]

So does a higher CAS setting advance or retard timing?

[QWK32]

standard is 15. (assuming you have a manual, auto is 20 i think). lower setting (10) is retarded and high setting (20) is advanced. from what your saying you have timing has been retarded.

[ak_stylez]

hmm. so, advanced timing makes the valves open sooner, right? this means air enters the cylinder earlier, causing the mixture to detonate sooner?

so if the base timing is adjusted back to 15 wouldn't that make the engine ping more? or is my logic flawed?

is knocking a result of advanced or retarded timing (or either).

edit: or does the CAS change ignition timing? in which case I can see that retarded timing would cause detonation because the spark is not igniting soon enough.

Edited September 27, 2007 by ak_stylez

[QWK32]

no no no..... the cas adjusts your base ignition timing, your thinking of you valve timing. your valves still open and close at the same time, with the cas you can adjust when the ignition/spark is fired.

so when you retard your base ignition timing you infact delay your spark. buy advancing it you make it spark earlier. knock will occur if your timing is too far advanced or retarded too much.

[ak_stylez]

ahh now i see. so really my tuner should have advanced the timing when it started pinging. But I'm wondering why it was retarded so much to begin with.

I'll give him a call tomorrow. Thanks Josh, you've been most helpful

[Pal]

i got 198 at 12 psi so 176 at 10 sounds about right, may need to tickle the timing as the guys say

[ak_stylez]

Hey,

well I spoke to my tuner today, he says that when he first started he put the CAS to 15 but it was pinging, so he put it back down to 10. Any ideas as to why we were not able to lean it out much? the AFR is about 10 right now. I'm thinking power fc will solve my problem.

Also got it compression tested with all cylinders coming in between 150 - 160 which is quite healthy so we can rule out any sort of piston leak.

[QWK32]

one thing to take into account is that as you manipulate the afm signal with the safc to trick the ecu in thinking its not getting as much air so it injects less fuel is that, when you tell the ecu its got less air it also doesn't add as much timing to the ignition map. the more you bend the signal to remove fuel the more retarded the ecu timing becomes from what it should be and then you get pinging.

with the safc you need to find the balance.

and start looking at other things, i just saw in your first post that you said you still have a side mount intercooler. i don't know how good the smic are but is it posible that it isn't cooling the air enough? the hot air would ignite the fuel before the spark and you'd get knock (ping). maybe? just a thought.

[ak_stylez]

hmm... perhaps. But i'm only running 10psi, plus it is an r34 smic (which is slightly bigger than the standard 33smic) and rated at up to ~220kw so I thought it'd be fine for as long as I plan on keeping my stock turbo.