Questions for first tune

[Yilld]

Hi guys,
I am new to all the ECU tuning and I did not want to just use a VT map and call it a day. I will start with a VT map and try to understand the changes to the stock map. For the understanding part I have some general questions and some regarding the VT base map. Car is a MPS6, closed AGR, TIP and catback exhaust.
1. I started with calibrating the MAF, now I see my LTFT values change every some miles. Am I correct to assume this is due to temperature, airpressure and fuel quality?
2. My catback is supposed to give a powergain of 14HP (which I'm skeptical of). Should I tune for that? I assume if so, I would watch for boost spikes and lower the BCS DC base table values accordingly?
3. Should I use a one step colder spark plug with the base tune or should I stick to the OEM?
4. The "overload protection fuel cut" seems very high compared to the other load values, why is this?
5. Why are the APP mapping different between gears (1,5,6 same and 2-4 same)?
6. Regarding the "Knock retared threshold": why is the max RPM at 5750 and not redline and why is there a min load and not always on?
7. Are "Requested Load multiplier accel/decel adjustment X Gear with APP increase" tables for shifting without lifting the APP and why are they changed between stock and base map?

I have attached the map I would use if someone would want to review it

I would appreciate any input
Andy

[mituc]

1. It's normal for the fuel trims mechanism to work. Even with a 100% correct MAF calibration it will be like that only in certain atmospheric pressure, humidity and ambient temperature.
2. this is not how an exhaust or other part is evaluated on a car that clearly targets load. However if the catback you have has more permissive resonators it will allow for sure some extra percent exhaust gasses to pass through, but only in absolute figures and when tested individually, because the biggest restriction on a factory exhaust are the catalythic converters.
3. even with the high load tune from the OTS tune library I recommend factory heat range spark plugs. But if you live in a hot climate and you use the accelerator pedal as your foot rest getting one step colder spark plugs will not hurt, and will not affect emissions either.
4. I suggest to set those back to factory values in your current tune. They are indeed very high and they can be reached only if the boost control will fail on the car. Anyway, they are even beyond the fueling capabilities of the stock fueling system. I usually set those lower myself for stock block cars that I tune.
5. gears 5 and 6 are longer (obviously) and the way the APP curve is designed is to give about the same feel and acceleration response . Why 1st gear is also like that? hard to tell, but I guess to make the car easier to drive or just feel more agile.
6. set that to 7000rpm first time you touch the tune. The factory rev limit is 6700rpm, however because the factory tune targets load at 6000 and 6500rpm below the knock load threshold (which I believe is set at 1.3 or something at 6000rpm and above) there is supposed to be no interesting knock in that rev range. However when we change these tunes for more performance we usually start taking advantage of that rev range as well.
7. I suggest to reset those back to stock. Those tables are supposed to kick in and adjust the load so that the car will not start bucking, protect the clutch, drivetrain, avoid boost/load spikes, and so on.

[Yilld]

Thank you for your answer.
1. That's what I thought..
2. Makes sense, I did not think of that..
3. Ok, I will stay with the stock heat range. Although we have 30°C at the moment, I would not call switzerland a hot climate. And the car is my daily, so the AP is usually no foot rest.
4. Ok, I will reset them to stock, or do you even set them lower than stock?
5. Makes sense for 5&6, and I think the Mazda engineers do know what feels the best..
6. I think it is just odd, because even if you don't have knock at this point, you could measure.. I'd rather measure nothing than not measuring knock..
7. I will reset those back to stock. But why are they changed in the VT base tune? Any input from a VT guy?

[mituc]

For #6, knock below certain load/rpm thresholds is just noise.

For #7 it depends on how do you want the car to respond after shifting gears. There are several ways to calibrate the tune for a car and basically change its personality through that. So the new values from the VT base maps are just as good.
I checked your tune and those tables are set for maximum response right after shifting. See how you get along with that. If you feel that right after shifting into next gear it feels like you dropped the clutch then get back to stock, otherwise keep it as is.

[Yilld]

6. I will just raise the knock redard threshold max rpm to 7000 rpm and leave the min load values as they are.
7. So this table does multiply the desired load by X during shifting?! For how long? So between stock and 1 it is just more aggressive during shifting and comes down to drivers preference (obviously harsh shifts are not good for the drivetrain)?

[mituc]

On 7, that is a multiplier for the load after you shift, for ike 1 second or so.
It is indeed a matter of driver preference, and to be honest no matter that multiplier there, no matter if the car is stock or highly modified, in the end it comes down to how the driver drives the car and if that is damaging for the drivetrain or not. Over time my conclusion is that the driving behavior is the most important aspect when talking reliability.

[Yilld]

So, I am at my tune again, so there are questions again:
1. Again regarding the Requested Load Multiplier, there are two sets. One "with APP increase" and one "Normal". So the first one is obvious, but when does the second one come into account? I've read I should lower the multiplier if I go from cruising to WOT and have a boost spike, so I would adjust the "with APP increase" one, correct?
2. For AFR Tables, why are there different tables (CL & OL part-throttle and OL WOT), and why is the part throttle one lower on some load levels than the WOT one? In my understanding I would want the lowest AFR at WOT and the other ones leaner?
Thanks

[mituc]

1. Unless you get a significantly larger turbo or want to tune for a specific issue I suggest you leave those tables stock.
2. The factory AFR tables are populated with values also having the NOx production quantity in mind. Sometimes depending on the temps you simply want a slightly richer mixture - when this is possible, to supply the 3-way converters with the right amount of ingredients for converting as much hidro-carbons as possible into CO2 and water and prevent the extra oxygen to combine with nitrogen.
Performance wise you are right, you want as much timing as possible and the leanest possible AFR for that RPM/load point, and that is what the WOT tables are for. Emissions wise too much timing and too lean AFRs mean more NO and NO2 (NOx), so the factory tune tries to address that as much as possible even when in open loop but only POT, not WOT.