Tony

Ok..now a question

On the WOT map shown below. Is it possible to have a closer scale on the rpm increments. The last three cells are 3700, 4800 and 6800. Why is the spacing like that and is it adjustable?

you can see where we added fuel. Prior to our last data log those values were 21...this added just a little too much fuel so we backed it off a little to 12 should be just about right i think.

scott863

Darien,

I never like new wheels on 928s, but yours look pretty cool, what kind are they?

Tony

Twin Turbo Twists..same on mine. A snap to clean!

Vlocity

Tony ....great thread. I am hoping to find someone close to finish tune or rent a ST from.

Ken

Cameron

Tony,

What a great thread. As an early user of the SharkTuner, I can attest to what a great tool it is for forced induction Sharks. When I was using the tool, the EZK module was not yet developed. But from a fuel mapping and AFR control perspective, even with the standard MAF I was able to achieve results that appear to be good in the charts, but are really evidenced by the night and day difference in driveability of the car before and after tuning.

Here are two links to some of my experience with the SharkTuner. In one of the links, Andrew so kindly graphed out my results for the community.

https://rennlist.com/forums/928-forum/261468-afr-test-results-sharktuned-shark.html

https://rennlist.com/forums/928-forum/260734-did-some-sharktuning-today.html

Andrew, I am surprised that you are experiencing a tip in issue on yours. You should be able to tune that out with the SharkTuner and it could be that it just requires a bit more time in tuning. I know that I spent more hours test driving than I originally thought. You may want to make sure that your TPS (throttle position sensor) is adjusted so that you get a slightly earlier WOT signal - that would give you the WOT table enrichment from the fuel map a bit sooner and may help.

Thanks again Tony for starting this thread.

John Speake

I've just been away for a few days, and found this thread waiting for my return :-)

Many thanks to Tony for starting and "hosting" this thread.

I will try and look in and help answer any questions that haven't been answered by other contributors.

I would urge anyone to re-read the User Manual (which is available for download from my website) AFTER they have had some time using the ST. Some of the text will have more meaning than when read "cold". I hope to put the LH2.2 version of the User Manual for download onto my website in the near future.

There seems to be some uncertainty in some people's minds about A/F ratios and WOT etc.

Most US delivered cars are still running with an O2 sensor in "closed loop" even if they don't have cats fitted anymore. For road cars I would always recommend staying with closed loop.

Closed loop also dictates that at idle and cruise you can only set the A/F ratio to stoich 14.7:1. It is only when you hit WOT at about 2/3 throttle travel that you can set your A/F ratio to whatever you want.

At WOT you can Autotune the high load/rpm cells on the base map to a common target value, so 13.5:1 or whatever you want.

If you then want to vary the A/F ratio at certain rpm (say 12.5:1 at 6500rpm) then you can do this using the WOT map, but you have to do this manually and there is no Autotune on the WOT map.

You can only enrichen the A/F set on the base map using the WOT map.

On Darien's injector duty cycle plot, he is into 2:1 pulsing and so his real duty cycle is about 80% maximum.

You can set the 2:1 point to high rpm with the ST if you want a straightforward % reading, as long as you aren't too close to 100%. The 2:1 function allows you to get a bit more fuelling per firing cycle out of the injectors. Porsche needed to do this with the 928 because the injectors in a standard S4/GT/GTS are at 100% at max power.

Thanks to everyone for their positive comments about the ST. Makes the effort worth while.

We are working on the EZ-F version of the ST at present.

Tony

good deal, thats what i thought, just wasnt sure....good stuff to know!
I hope i havent load your plate up John with you feeling obligated to constantly check in here and answer questions, that wasnt my intent. Any time you can chime it it will always be appreciated though!

this goes back to my other question...can the RPM values on the WOT map be edited so they are in closer increments? Technically there isnt a 6500rpm cell to edit? its quite a jump from 4800 to 6800 is what im getting at.

Tony

Darien and i were just talking about something similar to this. We have a slight hesitation off the line where the car goes lean momentarily as you jam your foot to the floor and hit WOT.
You may not have that part of the base map autotuned (unless it was done manually)..the cursor moves rapidly during some types of accleration and doesnt sit on a cell long enough to autotune it. You may have to go into your map to see where this occurs and manually add fuel. Or do an auto tune over that specific area and with combination of some particular throttle input and gearing? ie..do an auto tune in 3rd gear with a gradual role on from 40/50mph or something??
Andrew, what does you WOT map look like? I just spoke with Darien and we are going to manually enter values in the chart seen below...starting on the 990rpm cell and ending on the 4800rpm cell. What values we are going to add im not sure, but i told him to start at 22 at 990rpm and taper it off to 12 at the 4800 rpm point. We had good results adding fuel on the upper end at WOT (4800 to 6800)
There is only 1 time you are WOT at 990..1100...1300 etc rpm!(when you goose it from a stop) so we can dump the needed fuel for enrichment there via the WOT MAP with out effecting the idle and cruise maps ..! Im pretty certain that is the case

AO

Hi Tony... I don't have any screen shots from the ST. All I can tell you is that I'm pretty fat under WOT as DR wanted to build in some safety margin for me. My WOT seems happy, it's the cruise map (I think) that I'm having a few minor issues.

Louie928

Hi Brendan,
Well, it's sorta that way. When someone says "power" it's often construed to mean peak power. As another post said, it seems there isn't much left on the table in the stock maps. Another post postulated that you might get more out of a NA 928 with larger injectors and more fuel pressure, etc.

I was going to write a response to the last one, but I have to keep my stress down and I knew I would blow a gasket if I had to explain all over again for the umpteenth time that the 32V engines supply plenty of fuel already just as they are including whatever you can do with it for better NA breathing. Adding an )( pipe, better exhaust, and some intake mods are about all you can do and the stock fuel delivery system is fine. Remember that it does measure the air mass that the engine uses and provides the fuel as necessary. With an >< pipe and intake mods you maybe increase air mass flow by 10 - 12%. That's well within the capability of the stock system.

I've Sharktuned a couple of '85/'86 engines. I was quite surprised at how optimum the WOT A/F ratio was. Both of these cars had X pipes and no cats. I don't know what a stock one would do for AFR, but I bet it would be pretty close. The '85/'86 does benefit from careful timing advance. This is best done on a dyno. Bring the advance up slowly, like a degree at a time. As soon as you see an area of the power curve that isn't giving more power, don't advance more at that RPM range. Do not go until you hear pinging. Try a little more advance in the other areas until you've just reached the threshold of max torque from start to finish. Then back off timing by maybe a degree for some safety factor over all the RPM range. Do not tune timing with the best gas you can find because then you could have a problem with a poorer grade of fuel. The '85/'86 engines did make more power from bottom to top when the timing was optimised. The peak power of those two, one auto, and the other 5 spd, was about the same as my S4 5 spd. Lower end torque wasn't quite as much but not far off. Quite an eye opener for the performance potential of these models.

The S4's have not much left for peak power. Optimise AFR and timing and you can get maybe 5 hp. The S4s all run quite a bit too rich on the top end so leaning there to 13.2 - 13.5 can yield some. You won't get much from the S4 at the upper end with more advance because it is already about as close as you can get. It's not uncommon to get a few knock indicators on some cylinders with the stock timing. When you see the knock retard kick in, you can make a little by retarding the spark from teh base map so the knock retard doesn't cut timing back too far and hurt power. It's on the lower end where you can help S4s. I don't know why, but all I've worked with are quite a bit too lean below about 3500 RPM. It's not uncommon to see AFR of 16:1 at 2500 and WOT. Add some fuel where the WOT mixture is leaner than 13.5:1 and you'll geta a nice torque increase. Try more advance below 4000 and you'll probably get more gain. You can minimise the torque drop where the flappy switches by paying attention to fuel and timing there too. The ST lets you change the RPM & load where the intake flap switches. Do a couple dyno runs with teh flap open and a couple more with it closed. See where the curves cross. That will be your optimum flap operating RPM. Try some at partial load and see the results to find at what load the flappy should switch. Usually the stock settings are best, but sometimes the 5300 RPM flappy switch point back to closed is better to have it left open. I didn't mention it, but the MAF has to be accurate, or you are wasting time and effort with tuning. None of this comes quickly or easily. It's work.

Just for the record... Some time back I worked on a car (GT) that had an X pipe and 2.5" dual exhaust all the way back. It made good power. I removed the stock exhaust manifolds and installed good equal length headers. A huge job. Ceramic coated headers. I made a nice tapered transition from the 3" header collectors to 2.5" and into an X crossover and connected back to the existing 2.5" exhaust. I was anticipating great things for this already powerful car. The headers cost 4 hp. No amount of Sharktuning could get it back. Maybe a different transition, and X, would have helped and I'll probably experiment with it again. Point is, don't fret a lot over getting headers if you have an )( pipe and good exhaust behind that. It's going to flow as much as the 5L will put out.

Also, the air filter I use on my 6.5L engine is the stock 928 paper filter. It seems to be adequate. If you want fewer intake restrictions, work on the air box (increased cool air inlets), smooth larger radius passage from the air box into the MAF. You don't need a higher flowing filter element for a 5L engine.

One benefit of using the ST that is in addition to any power gain is that you can carefully tune out any flat spots and slight stumble. It seems like S4s have a little flat spot around 1700, at light throttle, and it's a lot more noticeable with a 5 spd than an auto. That can be taken care of. They idle nicer with about 3 degrees more timing advance. I leaned out my warmup map quite a bit and now it runs better right from startup. This took several days during the winter when it was cold. Start with a cold engine and check mixture and how it runs until it's warmed up a little. Probably 2 or 3 minutes of running. Let it cool off and do it all over again.

I get quite a few questions about what mixture to tune for at part throttle. You don't get a choice. At idle and part throttle it's running closed loop and that will give you close to 14.7:1 AFR. There is no setting on USA cars. Even if there were, why would you want it different? It's true that you can get a tiny bit better fuel economy by going to ~ 15.5 AFR and as long as the engine load is low, I doubt it would burn valves. There is a way to get the closed loop different than 14.7, but the couple tenths of a mpg gain isn't worth the effort. The LH will go to open loop at less than WOT when the load or RPM is high.

That's about all I can add/confuse at this time.

BC

And I am sure you have even more with your experience with your current EFI on the stroker.

John Speake

Hi Tony
I think there are plenty of people who will be able to use their ST experience and answer some of the4 more basic queries. I will chime in when there are more fundamental queries...... like yours here.

The maps that come with the ST are not "ST maps" - they are the maps that Bosch/Porsche wrote into the LH/EZK software during development.

We have modified the base fuel map to extend its range from standard.

Modifications to others map such as WOT are probably possible as there is still some spare code space available.

We are always open to suggestions to usefully enhance the usage of the ST.

It may well be possible to insert some extrra rpm points in the WOT map, if you can put a good case for it.

Why do you need different A/F ratios at 4800, 5800, 6800 etc ?

John Speake

Thanks Louie for yor usual lucid exposition on tuning stock 32v motors....... as you say, there are some gains to be made for tuning even a stock motor.

But of course the main reason for the development of the ST was for supercharged and turbocharged engines.

John Speake

Hi Andrew,
I'm just catching up on some of the points made in this thread.

There is no reason that your car can't be tuned to overcome the issue you mention. I am sure it is nothing to do with the 2:1 switching point. It probably has much more to do with the tuning of the high load load cells on the base fuel map that are explored at WOT.

As Tony says, any momentary weakening of the meixture can usually be tuned out by editting the acceleration enrichment parameters.

I don't think you are reaching 100% duty cycle on your injectors that would cause weakening of the mixture.

You really need to get the car on a ST again, and do some data logs under the conditions you describe to properly determine what is going on.

I can't stress enough that people should use the datalog facilty as part of the initial evaluation and tuning process. Then data log again when you are happy with the results of tuning, and save the datalog file for future reference.

BrianG

So, at what point(s) does the LH go open loop?
( I am trying to ascertain exactly which cells on the LH fueling map are subject to changeable A/F numbers.)

I thought WOT was WIDE OPEN but apparently this isn't quite true.....

There was mention of "about 2/3" throttle.....

Is this simply a function of hitting the microswich at the throttle body?

Is this normally an alterable parameter?