That can be controlled by the Open/Closed loop controls: or how the ECM responds to the factory o2 sensors. This part can only be tuned with a wideband o2 and datalogging present though. This and tuning decel fuel cutoff can have a marked fuel economy improvement on any car.

DoS

 

Great explanation.


My personal preference is to put the car into SD mode and dial in the VE table up to 4k rpm's. Then, reengage the MAF and rescale the MAF table.

IMO, if you can keep the MAF, and it doesn't max out, then you should.
If the MAF maxes out, then 2/3 Bar SD is the way to go.

The negatives to a full SD tune, would be the time that it takes (already stated), changes in the weather, and it needs to be done on a load bearing Dyno. That could add to to some cash for the time that it takes to do it. SD tuning on the streets at 6500 rpm's isn't very feasible either.

 

Great Explination!


You are so right about this. I have tuned and tweaked the hell out of many cars, and it simply takes time (after you have aquired the knowledge base necessary to tune) It almost seems impossible to make this kind of thing profitable right now. (SD tune)

Tommy

 

QuickSilver2002,
Thanks for the very informational write up.

Seperately speaking, I think that in consideration of my FI setup and my performace goal, my evaluation of tuning is leaning toward a good MAF tune from an experienced reputable tuner.
Chris

 

I'm glad the explanation helped.

Like Diynoob mentioned. EFI-live Flashscan has some features that really help with SD tuning. It is called autotune, but it is not really automatic.

It is basically a feature in the scan tool that lets you dynamically log a VE table if you have a WB hooked up. It logs the delta between the demanded AF and the actual AF and aggregates the data in the appropriate cells. You can then apply filters and automatically apply the resultant delta factors to the actual VE table.

It is useful, but not 100% fullproof by any stretch of the imagination. I use it, but always sanity check and go back and do quite a bit of manual tweaking.

Before flashscan I did stuff like this by hand with spreadsheets and that was very time consuming.

You can also use this same feature on a car with a MAF and can have it create your PE vs RPM table for you. It is not quite as obvious how to do it, but I can explain how if someone wants to try it.

 

That's a great writeup QuickSilver!!! I think we're pretty lucky to have members which can comprehend as thoroughly on this forum.


I've run SD for a while now and the one thing I'll always remember was how much smoother the car was shortly after converting. The bottom line is that finer or greater control always leads to more potential... positive but also negative.

Although people have tuned SD w/o a WB it's 1000 x's easier w/ it due to the autotune features. Proper sync of the WB to the tuning program is critical since.. if it's not setup right you wont be able to autotune.

IMO, there are three steps to getting an SD tune on one non-SD to begin with. They all take their fair amount of time but the good thing is that all three isn't repeated on successive tuning sessions and should be easier on the schedule or pocketbook.

1). Setting up and calibrating the tuning program w/ the WB. If the tuning program isn't seeing what the WB is really telling it then you can't autotune. Some people have had difficulty getting this done... like myself.

2). Calibrating the tune. This is where all the various parts of the tune get in order so that what we command is what we get. For example, if I command an AFR of 13.0 no matter what load and rpm, I get it. I want an AFR of 10, I get it. The point is this isn't tuning for power, it's a calbiration process. This involves logging.. alot of it. Since sampling/logging is done at multiple load(boost) points at specific rpms, it can take time but once complete, the most time consuming part of SD tuning may be over. This is also the part of the tune that needs to be updated when additional mods are made.

3). Tuning for power. The matter of changing your commanded afr and timing to achieve the greatest hp/tq. This is where you can take now a 4hr tuning session and make it 2 days if you want. Because you can literally (on a load dyno) sit at an rpm and each load (none to full boost and any point in between) and see what gives you the most hp/tq. You would then go to the next rpm and do the same thing. How granular you or your tuner wants to get is going to determine time.

So.... can you make a MAF tune better in SD? It's definitely possible.

Arnel

 

Arnel: ( Or anyone who could answer this question)
In my situation where the car is in the Bay Area, but I live in Las Vegas is SD still ok? Heres my real question... I will be swapping between 3 different pulleys 9.5, 11, 13 psi. I gonna have Rick tune the car with the 11psi pulley on it. Buttt, I do not have the capabilities to "Tweak" my car while I am in Vegas. So it will literally have to be "Set it and Forget it". Not only do I have the software to support it, but al the tuners in Vegas SUCK.

I will most likely never leave Las vegas with my car so there should not be any geographical changes. But it will most definately have atmospheric changes due to our extreme heat. We can go from 120+* with 11% humidity, to 45* with 35% humidity.

I will not be racing this car, so I am NOT concerned with every last HP. What I am mostly concerned about is how smooth the car runs, as well as how crisp it runs.

Jeff

 

Changing pulleys alters the power band, at least in the centrifugal world.

So, if one tune is perfect for every amount of boost and every weather condition, then in theory your tune would work perfect for two cars with the same mods ??

Mark

 

Since I don't have nearly the experience or know-how of Rick I could only assume that based on the logging of your car at known quantites, he could do a pretty good job predicting what it would do at 16 and your weather, elevation, etc. SD still considers air and coolant temp so it'll be able to handle it to some degree.

Hopefully, Rick will chime in...


Arnel

 

If every area on your VE map that you will hit with the three pulleys is dialed in (very time consuming). Then you can switch to whatever pulley you want and it will be very close to optimum. As long as you don't max out your map sensor. Especially if he is using EFI live. It has provisions for changing IAT's ECT's.

 

A great writeup QuickSilver.