Desired AFR not matching whats in tables and rich condition on spool up.

Discussion of tuning specific to MAZDASPEED6/MAZDASPEED Atenza/Mazda 6 MPS vehicles
mituc
VersaTuner guru
Posts: 1324
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Desired AFR not matching whats in tables and rich condition on spool up.

Post by mituc »

So as I said before you need to tune out that high load in lower gears which is basically riding the line of load fuel cut pretty much every time. At this point you are asking for a bit more WGDC than you actually need so I'd start with that. I'd rather have the throttle open more and have load/boost control through that than having high WGDC and having the throttle close down to modulate. As you can see basically you have a boost spike in those lean spots and that kind of takes the ECU by surprise and it needs a few cells to mitigate, and because how things work this takes more cells in lower gears.

Also, if your engine is not build it may not survive too long at load values close to 2.4 at such low RPM. It's ok if it's built though.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Lolmooses
Posts: 43
Joined: June 16th, 2020, 1:53 pm

Re: Desired AFR not matching whats in tables and rich condition on spool up.

Post by Lolmooses »

I followed what you suggested and success! It still dips rich on spool up but that damn lean spot is finally gone. It still needs work but the biggest issue is fixed. Thanks a lot for the help :). Maybe that should be added to the respective absolute limit table descriptions so others can know in the future.

My engine is not built unfortunately, but following your advice I've decided to ramp up to 2.35 by 4000 from 3000 instead of just shooting for it right off the bat.
Attachments
3rd Gear Pull 8-6-20.csv
(2.3 KiB) Downloaded 205 times
2006 MS6: CS HPFP internals, stage 2 CS intake, CP-E TMIC, CS catback with racepipe, GFB hybrid BOV, CS EBCS
mituc
VersaTuner guru
Posts: 1324
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Desired AFR not matching whats in tables and rich condition on spool up.

Post by mituc »

Lolmooses wrote: August 6th, 2020, 2:26 pm It still dips rich on spool up but that damn lean spot is finally gone. It still needs work but the biggest issue is fixed. Thanks a lot for the help :).
The logs look absolutely fine now. AFR of 10.97 when the target is 11.02 is only 0.05 off which is nothing. You will get more than that when the weather will change.
Lolmooses wrote: August 6th, 2020, 2:26 pm My engine is not built unfortunately, but following your advice I've decided to ramp up to 2.35 by 4000 from 3000 instead of just shooting for it right off the bat.
An engine that is not built has two potential issues when it comes to tuning it:
  • low end torque. Targeting too much load, which basically translates to torque - on relatively low RPM can bend rods. If that is done in the early stage of tuning when the timing is not dialed-in yet and you also get some knock in that rev range things can go wrong.
  • Heat. High loads commanded up in the rev range will result in a lot of power which also means a lot of heat which the factory pistons cannot withstand for long and can crack ringlands. Running high load with very low timing for the type of gas you are using will also elevate the heat in the exhaust which will cook turbos, cats, but first this heat will get to the exhaust valve o-rings and guides
Of course we all acknowledge the risk of tuning, or even of using a car close to its max potential even when stock. But knowing what the limits are on this platform helps a lot, so we'd rather exceed those limits being aware of them rather than just going for it and being sorry later. So now you know :)
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Lolmooses
Posts: 43
Joined: June 16th, 2020, 1:53 pm

Re: Desired AFR not matching whats in tables and rich condition on spool up.

Post by Lolmooses »

For sure, it's always a risk, like running the MAF cal from Cobb hahaha. I'm still surprised I didn't send a rod into the pavement that day 😬 Feels good when things get figured out though so there's at least a balance there haha. Im going to guess excessive heat up top probably doesn't become a big issue until you go with a bigger turbo? If the tune is reasonably well done on the K04 that is.

I have to say, the more I understand these engines and how to tune them, the more I realize the stock K04 is a poor match. You can't target high loads at low RPM, which wouldn't be a big deal if it didn't run out of efficiency after 5000. So you have this narrow power band of maybe 2000-2500 RPM which kinda sucks...I have a carted downpipe going in soon which I'm sure will help but I get the feeling it won't be a huge improvement in top end. Not until that turbo gets replaced at least.
2006 MS6: CS HPFP internals, stage 2 CS intake, CP-E TMIC, CS catback with racepipe, GFB hybrid BOV, CS EBCS
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