She wheelies!!!!

[mosho93]

Very Impressive Tom, cant wait to see vids of it boosted! :corn:

 

[lightningtroy]

What are u using to determine af ratio? are the screens posted ones u actually use? I have yet to find any info on how to actualy determine injector breakpoint, i know it happens barley off idle 1-3ms but using this function is only helpfull in limited applications and should be used only as a last resort. The problem with using the tweecr is that u are changing the pw to correct the af ratio but you are not correcting the timing table. the pcm uses maf output to determine base pw AND timing. if the maf transfer function is off the timing table will also be off hence correcting pw only fixes half the issues. you're high and low slope values are drastically different from one another indicating a problem with to high of fuel pressure or a maf sensor that is way off. i would also like to see the grafts recorded at the same time interval.

 

[AutoSHO]

Actually, we can change injector timing as well. As I said before, we have access to every aspect of the PCM's programming.

The breakpoint is a last resort, as you've noted.

The difference between high and low injector slopes is how Ford programmed the MTXs stock.

The PCM bases injector timing on load, which is calculated by the MAF as well as TPS inputs mainly.

Using a wideband oxygen sensor I can correct the MAF curve to nearly perfect in one datalog, for high-load numbers especially (anything above ~200 kg/hr). Injector timing tables should not need to be drastically changed for a stock or near stock car - even a lot of the blower cars run stock injector timing. The Mustang guys have found extra throttle response and power in playing with injector timing, I just haven't had time yet to mess with that aspect of the programming.

The ATX programming is a lot more complex in terms of spark calculation than the MTX programming. There is a lot more variation in how much timing it can and will run, too. Unlike the MTX, you do not get to command one specific spark curve for WOT - only a general curve for higher load.

 

[lightningtroy]

Sorry for not being clear. i meant the pcm uses maf to determine base pwand IGNITION timing. how are you correcting the maf without programing the correct transfer function? if you are adjusting the afr via the the fuel pw you are only adjusting for the effect not the cause( maf transfer function values)

 

[AutoSHO]

The MAF transfer function is typically entered before I use AFR's to correct it. I've found through tuning that each MAF responds differently than the next, especially due to piping/airflow variation. Therefore, once I put the correct MAF transfer function in, I can fine tune it to the individual application. Provided I know I have the correct injector slopes programmed in (which I can also do via wideband) then I know the MAF transfer function is all that needs corrected in order to run properly.

 

[Sho-Driver]

We do insert the correct transfer fuction, which should be a given. Adjusting the high/low slope telling the computer whether or not to hold the injector open longer or shorter based on PW(RPM,load, etc). We are not actually changing the pulse width, but the injector slopes associated with them Getting these values correct for any specific setup will keep the computer from having to learn so much.

Your high and low slope values are drastically different from one another indicating a problem with too high of fuel pressure or a MAF sensor that is way off.

There are more computer binaries out there.....

As far as my numbers are concerned on high/ low slope, you are trying to tune an ATX computer. Have Tom bring you an MTX computer and take a look at it. The stock MTX injector slopes are 27.4181 and 72.0008

I have been toying with the idea of changing the injector timing as I have different cams. Stock cams, I would not worry about it.

The problem with using the tweecr is...

There is no problem. Like AutoSHO has stated, we have access to change what ever we desire. The TwEECer will allow a user to data log at anytime and make a real-world change without having to take it to the 'tuning-guy' to get another shot at it.

 

[lightningtroy]

Again, sorry for the confusion. i ask to learn, no one had stated that the maf transfer function could be entered. i also have some questions on the use of terminology?

Pulse width= the time the injector is open? measured in ms
Injector timing= when the injector fires in relation to intake valve opening?
low slope= the amount of fuel a injector flows in lbs for a given pw usually 1-3ms?
High slope=the amount of fuel in lbs for a given pw usually 3ms and up?

I have tuned some cars with F.A.S.T., The ford epec(on my car now), motec, weber-vw, and have never used these high/low slope values. i have always used pw to adjust af ratios. :corn:

 

[lightningtroy]

Auto-sho are you a designer/dealer of th teeecer?

 

[AutoSHO]

Again, sorry for the confusion. i ask to learn, no one had stated that the maf transfer function could be entered. i also have some questions on the use of terminology?

Pulse width= the time the injector is open? measured in ms
Injector timing= when the injector fires in relation to intake valve opening?
low slope= the amount of fuel a injector flows in lbs for a given pw usually 1-3ms?
High slope=the amount of fuel in lbs for a given pw usually 3ms and up?

I have tuned some cars with F.A.S.T., The ford epec(on my car now), motec, weber-vw, and have never used these high/low slope values. i have always used pw to adjust af ratios. :corn:

Pulsewidth: Yes, length of time the injector is fired by the PCM.
Injector timing: Injector firing in relation to crank rotation. Same basic idea, but it is referenced to degrees of crank rotation.
Low Slope: Predicts injector behavior at low injector pulsewidths
High Slope: Predicts injector behavior at higher pulsewidths
Breakpoint: The point where the computer interpolates the high and low curves.

The high & low slope values are Ford programming to my knowledge - I'm not sure how you would change injector pulsewidth directly, as pulsewidth is determined by MAF voltage, TPS voltage, commanded A/F ratio, and engine temperature primarily.

Auto-sho are you a designer/dealer of th teeecer?

No sir, just a satisfied end-user. I have a lot of experience with the software, as well as an earlier software package made by "EEC-Tuner". It used very similar scalars, tables, and variables, but did not have datalogging capabilities, which make a huge difference. The ability to datalog engine parameters as well as outside variables (dedicated MAP and Wideband inputs) makes it very easy to tune the car.

 

[lightningtroy]

I have never seen any ford info regarding low/high slope, i have been looking through my factory ford training manuals trying to find any info on this subject with no luck. i would love to see some factory info on these values. when i diagnose many vehicles with fuel system related issues i often monitor pw to help me determine what the ecm is trying to correct for-abnormaly high pw= lean conditions, low pw= abnormaly rich conditions. This pw varies according to tps/load/maf. I can also force pw to change by creating vacuum leaks or by adding fuel. this is the value i change to adjust afr. watching pw on a lab scope you ill see pw change with throttle movement, this is the value i add or subtract to adjust afr i also use this value to determine when injector duty cycle is maxed out.pw is what changes when the ecm is making fuel trim adjustments for what ever reason. i belive high/low slope is used by engineers during design of an engine and its programming and should be considered a fixed value. i find it very interesting that these values are adjusted to to change afr, i tottaly understand how they can adjust afr-just not why this would be a preffered method-or not.i am always concerned with "stacking of calculated values" and try not to adjust any fixed values. to give you an example it would be like entering a value for a 5.0 when the eng is really a 4.0 the result may work but what may have been overlooked? all aftermarket engine controllers i have used adjust pw to controll the amount of fuel the eng. recives. :corn:

 

[lightningtroy]

P/S, my question regarding designer/dealer of the tweecer was directed at sho-driver

 

[Sho-Driver]

I'll just quote AutoSHO as he said it best...

No sir, just a satisfied end-user. I have a lot of experience with the software, as well as an earlier software package made by "EEC-Tuner". It used very similar scalars, tables, and variables, but did not have datalogging capabilities, which make a huge difference. The ability to datalog engine parameters as well as outside variables (dedicated MAP and Wideband inputs) makes it very easy to tune the car.

 

[AutoSHO]

i belive high/low slope is used by engineers during design of an engine and its programming and should be considered a fixed value. i find it very interesting that these values are adjusted to to change afr, i tottaly understand how they can adjust afr-just not why this would be a preffered method-or not.i am always concerned with "stacking of calculated values" and try not to adjust any fixed values. to give you an example it would be like entering a value for a 5.0 when the eng is really a 4.0 the result may work but what may have been overlooked? all aftermarket engine controllers i have used adjust pw to controll the amount of fuel the eng. recives. :corn:

High/Low injector slope tell the computer how much fuel the injector flows. Instead of putting a band-aid on the problem by adjusting how much fuel the computer calculates to need, instead you are telling the computer how much fuel the injectors will flow, so that it can accurately determine how long the pulsewidth should be for a given amount of airflow as dictated by the MAF.

The Injector Slope is one of the root values used in the programming. The stock Ford program actually stacks calculated values with the KAMRF values (Corrective fuel trims). The KAMRF value is what the computer muiltiplies the commanded AFR by in order to achieve the original desired AFR. In other words, if the car is having to command a 14.0 AFR to run a desired 14.7 AFR, it applies a KAMRF multiplier of less than one in order to correct the discrepancy between the MAF and injector's actual flow rates.

How exactly do you adjust pulsewidth directly? Are you changing the air/fuel ratio the computer is commanding? I've never seen a standalone, programmer, or otherwise that just has a table of injector pulsewidths for given loads/rpms. I'd love to see an example of this.

I believe that by changing the injector slope, we are going to the root of the cause instead of jsut trying to change the computer's output to match the desired result - By changing the numbers the computer uses to calculate, instead of changing the numbers it calculates, you end up with a PCM that can more accurately add fuel and get the mixture right all the time.

FWIW, by tuning the injector slopes, guys with a wideband have been able to set the commanded AFR's to 13 across the board, and the car will run exactly 13:1 all the time - That is how accurate tuning the injector slopes can be.

 

[Off Road SHO]

You guys are making my brain hurt.

 

[lightningtroy]

:laugh_ti: HaHa you drank you're milkshake to fast!

 

[NotSoSlowSHO]

You guys are making my brain hurt.

Im in the same boat Tom .

Im trying to follow it, HONEST! As I want to get into the actually tuning of the SHO some day.

 

[K-Dawg]

Thanks for discussing this stuff guys. I've learned a lot.

Now start some more arguments so I can learn some more!

 

[Off Road SHO]

No, lightning troy needs to get back to work on The Other Woman so that we can get back to doing the title of this thread.

Tom

And I can go to the dunes and start kicking some LS-1 butt!

 

[Toolman]

SO who wants to tune my turbo SHO?

 

[Off Road SHO]

Well, definitely not me. This stuff is so far over my head I have to keep looking up to even read it.

Tom