OFT - Guide To Dialling In Your OTS Base Tune

[jvincent]

Originally Posted by solidONE

This load limit table is like a new "toy" within a toy to play with. lol I will have to double check what the MAF scale look like at the AFR spike. Thanks for the heads up @jvincent

It definitely looks good.

If you don't mind posting up the MAF scale that corresponds to the spike that would be great.

The thing that bugs me about the load limit changes being discussed is they all seem to introduce an "inversion" in the graph and I can't think of a scenario where that would make sense.

I would expect most of the curves/tables the ECU uses to have linear/exponential shapes leading up to and away from a peak value. This would be in line with a peak value corresponding to a resonance point in the fueling system.

I hope that made sense.

[KoolBRZ]

I started with the AT RTBt w/MT LLts, (requested torque B table from auto, and load limit tables from manual trans ROMs). Power delivery was smoother, quieter, but slower, and used more fuel to get there. Next I tried the MT RTBt w/AT LLTs tune. It was louder, but gutless below 4000 rpms, also it would rubber-band shift 3-4 times in 4th and 5th gear. (that's where it bounces after a manual shift in an AT trans, like the car is on a big rubber band). This is still better than the MT RTBt MT LLts tune. That did even worse than rubber-band, it popped and almost stalled after manual shifts. I've learned that lower limits work better in the lower range for my tune with an AT RTB table. I'm going to try lowering them a bit more and see what happens.

[solidONE]

Originally Posted by jvincent

Just curious why you would want to try to use load limits to smooth out the AFR here instead of improving the granularity of the MAF scale in those areas?

What does your MAF scale look like in that region?

I'm going to guess that at the point where your AFR peaks to 14.59 you are just to the right of one of the defined MAF voltage values so it is interpolating based on the previous point and the next one and because the next point is far enough away the interpolation error is large.

I'm messing around with exactly this right now and have an adjusted MAF scale which uses more points in the 2.5 to 3V range which is the most problematic. Just waiting for my trims to finish learning before I log it.

I went ahead and took a log hanging the MAF voltage around 2.7~2.8v in CL to see how much fuel trim is going on in that area:
http://datazap.me/u/solidone/maf-27v...zoom=4153-4261

about +2% total adding the LTFT and STFT together, so not too bad.

Here's what it looks like around those voltages:


The difference between 2.689~2.844v is only about 7.5 g/s. Doesn't seems like a huge step up or down the scale, but who knows.

Although I've notice that this afr lean spike always happens at about 2260rpms under WOT where the engine load also spikes past 1.20 g/rev. So I think it's safe to say it's not the MAF scale causing or contributing to this spike nor can it be dialed out by changing the MAF scale. What do you think?

[jvincent]

Thanks for posting the table.

In the OL log you posted you get the AFR spike at 2.78 volts and sure enough you have a MAF table entry of 2.76V. My guess, and I am really guessing, is that the interpolation is creating the high AFR somehow.

If you had a couple of more data points between 2.5 and 3.0V maybe it would have less error, or maybe it wouldn't.

As a general point though I would always want more points in the area of the curve where a linear approximation is the worst.

[solidONE]

Originally Posted by jvincent

Thanks for posting the table.

In the OL log you posted you get the AFR spike at 2.78 volts and sure enough you have a MAF table entry of 2.76V. My guess, and I am really guessing, is that the interpolation is creating the high AFR somehow.

If you had a couple of more data points between 2.5 and 3.0V maybe it would have less error, or maybe it wouldn't.

As a general point though I would always want more points in the area of the curve where a linear approximation is the worst.

Well, I've totally ran down this tank of E85. I will try the same tests on the 91 petrol tune to see whether if this spike also occurs there. While running the E85 the engine is not to fussy about lean spots in the afr,but I'm sure once the 91 piss water gets added in the tank it will be. I'll post up what I find after my second tank of petrol.

edit: @jvincent Check out that same log and where I marked it: http://datazap.me/u/solidone/plm85g-...2109-2094-2097

@ 2154rpm the maf voltage was at 2.76v and .31 below target afr
@ 2291rpm maf 2.75v .73 above target afr

again @ 2528 rpm maf 2.88v and .38 leaner than target afr
@2858 rpm maf 2.88v and .31 richer than target afr

At the same maf voltage in 2 separate points on this pull can be either too rich or too lean. What this tells me is that changing the maf scale probably will on only have the desired effect on one of those points with the same maf voltage, but not both of them. So, I should be adjusting something else besides the maf scale (eg. load limits) to get it right. Yes? Or I can make the MAF scale richer to fill in the lean spots, then use the load limits to bring up the afr at the rich spots. Either that, or I can just leave it alone if there is no knock and not waste too much time. lol

[KoolBRZ]

Originally Posted by solidONE

Well, I've totally ran down this tank of E85. I will try the same tests on the 91 petrol tune to see whether if this spike also occurs there. While running the E85 the engine is not to fussy about lean spots in the afr,but I'm sure once the 91 piss water gets added in the tank it will be. I'll post up what I find after my second tank of petrol.

The way I see it, load limits are a way of preventing overfueling when the engine simply doesn't need the extra fuel. Wayno is saying that they should be changed if there is a DIFFERENCE between WOT and half throttle logs at the same MAF voltage. This indicates the same airflow, but a difference in air/fuel ratio at different throttle/requested torque. Are you changing your load limits to affect these differences, or are you just trying to smooth your MAF scaling? Question 2; Are your tunes labelled with the letters PLM because you have the PLM/Nameless long-tube header?

[solidONE]

Originally Posted by KoolBRZ

The way I see it, load limits are a way of preventing overfueling when the engine simply doesn't need the extra fuel. Wayno is saying that they should be changed if there is a DIFFERENCE between WOT and half throttle logs at the same MAF voltage. This indicates the same airflow, but a difference in air/fuel ratio at different throttle/requested torque. Are you changing your load limits to affect these differences, or are you just trying to smooth your MAF scaling? Question 2; Are your tunes labelled with the letters PLM because you have the PLM/Nameless long-tube header?

To your first question. Yes, that is exactly what I'm doing. I find my MAF scale very very satisfactory under CL operation up to 3.0v.

2. They are long tube headers I traded my Tomei EL for. That's all I'll say.

[KoolBRZ]

Originally Posted by solidONE

To your first question. Yes, that is exactly what I'm doing. I find my MAF scale very very satisfactory under CL operation up to 3.0v.

2. They are long tube headers I traded my Tomei EL for. That's all I'll say.

I also have a long-tube header. I started changing my AVCS tables just to take advantage of that header. Check out these tables for my Intake and Exhaust. This is part of the reason why I need to change my load limit tables.

[solidONE]

^ Looks to be very aggressive. How are you testing the effects of changes to the cam timing?

[KoolBRZ]

Open-road tuning.

[solidONE]

Originally Posted by KoolBRZ

Open-road tuning.

Do you dyno after you make changes to the cam timing? What kind of power are you yielding over baseline with those cam tables?

[KoolBRZ]

Originally Posted by solidONE

Do you dyno after you make changes to the cam timing? What kind of power are you yielding over baseline with those cam tables?

I'm not trying to improve WOT performance. I want to improve mileage and daily drive-ability. These tables have enabled me to get 36 MPG highway, and yet in the city stop and go, it has enough power to be fun to drive. They work perfectly with lower load limit tables, and the AT RTB table for a quick surge of power from a standing stop. I've been to the dyno numerous times, and all it shows me are full throttle numbers. I don't drive at full throttle all the time, so that isn't helping me. I've worked for months making changes to the AVCS tables to get to where they are now. I have the Phantom ESC, so I can still turn it off to feel how it drives without boost. I've felt I must be affecting some kind of limit, since even small changes had a large effect. I know now it was Load Limits. I will be reinstalling my OEM header and front pipe soon, since I need to pass DEQ this November. This will give me a chance to see how my AVCS changes work with a stock header.
I do PC repair and drive to as many as 5 customers a day in the Portland/Vancouver area. I need a car that is fun to drive, yet gets at least 30 mpg on the highway. I like to slide, so I prefer a rear-wheel-drive car. The trunk has enough room for my parts, accessories, and 2 towers, or a tower and a monitor, (flat screen). I'm heading into downtown Portland to see a customer now. Right after I flash a tune with even lower load limits.

[solidONE]

That's pretty awesome! Take it it to the track and you got a "triple-duty" car! Daily, work/delivery, track. lol
@KoolBRZ can I check out some of your logs if you have them uploaded on datazap?

[jvincent]

Originally Posted by solidONE

edit: @jvincent Check out that same log and where I marked it: http://datazap.me/u/solidone/plm85g-...2109-2094-2097

@ 2154rpm the maf voltage was at 2.76v and .31 below target afr
@ 2291rpm maf 2.75v .73 above target afr

again @ 2528 rpm maf 2.88v and .38 leaner than target afr
@2858 rpm maf 2.88v and .31 richer than target afr

At the same maf voltage in 2 separate points on this pull can be either too rich or too lean. What this tells me is that changing the maf scale probably will on only have the desired effect on one of those points with the same maf voltage, but not both of them. So, I should be adjusting something else besides the maf scale (eg. load limits) to get it right. Yes? Or I can make the MAF scale richer to fill in the lean spots, then use the load limits to bring up the afr at the rich spots. Either that, or I can just leave it alone if there is no knock and not waste too much time. lol

Good question. There's probably a few things going on. The one's I can think of off the top of my head are:

1. Inherent inaccuracy in the various sensors. Like everything else, they probably have at least a couple of percent error in their readings.

2. Effects of the various compensation tables.

At a certain point we're probably being over anal about getting a perfect match.