Stage 1, targeting 17 psi... losing power after 5k.
So, I've been tuning with ATR for about a month now on my 1 gen MS3 and more recently I've started to experience the "5k rpm power drop" these cars are known for. Obviously the first step was to take logs and see where I was at. The first log look great, but wanting a little bit more out of the car, I started tweaking things and now I'm targeting 11.8 AFR and 17psi with WGDC controls.
My engine mods are:
Denso V22 Plugs
I started off with the Cobb 91 oct Stage 1 + SRI map. Did a few iterations of MAF calibration, then targeted 11.4 AFR. Once I was happy that was sound, I upped to 11.8. From there, I altered loop transition tables to make it jump to OL quicker. Then targeted 17psi. All following Abilor and bucker's guides on MSF. I've since gone through a few iterations of WGDC settings trying to smooth out my boost so that I'm not spiking at 3k rpm ... however I've also started dropping power about 5k.
These logs were not all taken at the same temps, or the same stretches of road. But the thing that I'm interested in is why I'm currently dropping power after 5k.
In the day 1 logs i kept gaining power to the rev limiter... but in the most recent logs, I'm going back to the old "5k rpm drop" that is similar to the stock tune.
Day 1 (roughly) https://docs.google.com/spreadsheet/...3IwQ2lFenJnX1E
Day 1 again: https://docs.google.com/spreadsheet/...jlkc0lIZm9ucWc
Current : https://docs.google.com/spreadsheet/...HYtZzBSZVBfRkE
blah blah... any thoughts are appreciated.
Any insight into why I'm suddenly dropping power after 5k?
Last edited by Workdawg; 04-21-2012 at 07:03 PM.
Well i can tell you this, the tune from the current logs should be definitely making more power , just glancing at the load your hitting and the amount of air going in, ( almost 280 g/s) compared to the Day 1 logs which have much lower load and air ( 240 g/s)
The biggest reason that i can see for making more power past 5k on your Day 1 Logs, is due to the ignition timing. If you look at the 2 logs, your running a lot more advanced ignition timing on the Day 1 logs, making the car pull much harder than the other.
Just because your holding more boost on the current tune, doesnt necessarily mean your going to be much faster. There are guys on MSF forums that are experimenting with low boost/extremely advanced timing tunes, and actually putting up some suprisingly good numbers.
But yea, thats why your Day 1 tune is pulling harder than the current setup, your timing is way more advanced.
Hope that clears it up for ya
That's pretty much what I could come up with as well, but does that really explain why power actually drops off? I spent a while graphing out timing, RPM, boost, etc and it looks like timing is still increasing at roughly the same pace in both logs, just obviously staying lower overall in the most recent one. I guess I would have expected to notice a difference at high RPMs where I lose power.
I've read up on timing a bit more and have some questions...
So, the first question is, is it worth it to mess with timing despite my only moderate mods and 91 oct? It's worth mentioning this is my DD and I'm interested in reliability over max power. If I can squeeze a bit more power out of the car without causing any real damage, then that's great.
If so, the stuff I've read seems to indicate that I need to look at the timing for the specific RPM and loads I'm getting during my WOT runs.
WOT (no knock)
So for Log1 from above, that'd be:
2500 RPM, 1.20-1.95 load (1.19,1.25,1.31,1.38,1.44,1.50,1.56,1.63,1.69,1.75 ,1.81,1.88,1.94)
3000 RPM, > 2.0 load (2.00)
3500 RPM, > 2.0 load (2.00)
4000 RPM, > 2.0 load (2.00)
4500 RPM, > 2.0 load (2.00)
5000 RPM, 1.94-2.01 load (1.88,1.94,2.00)
5500 RPM, 1.79-1.91 load (1.75,1.81,1.88,1.94)
6000 RPM, 1.67-1.77 load (1.63,1.69,1.75,1.81)
6500 RPM, 1.60-1.64 load (1.56,1.63,1.69)
Covering slightly above and below each RPM/load range (as phate described). I just increase timing .5-1* at a time until I reach knock at a particular RPM/load value and then back off as much. (or test with higher octane to see if it's mechanical or real knock).
Values would be copied to the WOT (knocking) table and reduced 2*, and copied to the MAX table with +2*
Does that sound about right?