Tweecer question?

[yamahaSHO]

I'll have to admit, I haven't spent much time looking through the ATX files... It's been YEARS since I have too.

I would prefer ONE global spark adder on our cars too.

 

[hawkeye18]

Oh. Ok then, I guess I'll take it back down to 4, which is what it was set at from the LPM. You say that 4 is the optimum number then? I mean, yes, every car is different, but I figure you'd know more than anybody...

ALSO! Another question, and one I've been dying to ask you. According to charts, at 7K rpm, in first gear an ATX (assuming the TQ is locked) should be going 51MPH. For a while I was setting my shift point at that forgetting about the TQ not being locked, and it took forever to shift and kept bouncing off the redline (which was at 7600 [yes, I have UDPs]). Obviously this was waaaay past the useful power of the engine. Finally it dawned on me that the TQ wasn't locked, so I took the value down to 45 for the 1/2 shift and it works better but it still seems to take a while to decide to shift.

The question is: what would be a good MPH number to tell the tranny to shift at 7000 RPM for? Also, does the scalar "Trans - WOT Shift point 1-2" do anything for you? Cos I have it set to 6800 and it shifts well above there. Which function takes precedence?

 

[Axianator]

Oh. Ok then, I guess I'll take it back down to 4, which is what it was set at from the LPM. You say that 4 is the optimum number then?

Well, 4 degrees seemed to be the default value that Ted would use for his boilerplate ATX programs. However, my '95 never liked that that much advance, and like Porter, my SHO never made as much power with 93 octane gas as it did with 87. Throttle response didn't seem as snappy, and the dyno only revealed an increase of ~4whp when I was using Ted's LPM with 93 octane "premium" gas.

Back when I still had my factory 3.2L, I ran--at most--2.5 degrees of added advance via the global adder. Now, I run a set of modified timing tables with only 1 degree of advance through the global adder with my low-comp 3.3L. Very soon, that 1 degree of global advance will be phased out and moved into the appropriate timing tables and adder functions.

Bottom line, you don't want to use the global adder for anything. While it's handy for all-purpose calibrations and even diagnostic testing, it's a cheap and easy way of tuning. A "real man" makes all of his timing adjustments in the areas where they really need to be made, just like he would do for any other part of his calibration.

Also, Jason is correct: every car is different, and your results may vary slightly from my own.

The question is: what would be a good MPH number to tell the tranny to shift at 7000 RPM for?

Personally, I command a WOT 1-2 shift at 45 MPH using the "Trans - Sealevel 1-2 Shift Schedule" function in my personal calibration. That puts me close to 7,000 RPM on my ATX with the stock gearing and factory-sized 16" wheels. Dyno testing has also shown that, with my low-comp 3.3L and factory cams, I'm starting to lose power by that point anyways, so there's no reason to further stress the tranny by shifting any later than I already am.

Also, does the scalar "Trans - WOT Shift point 1-2" do anything for you? Cos I have it set to 6800 and it shifts well above there. Which function takes precedence?

In an ideal world--say with an ATX Mustang calibration, that scalar would take precedence over the shift schedule functions, causing the tranny to shift at the specified value during WOT operation. However, this does not seem to be the case with the ATX SHO calibrations, nor have I noticed any change in behavior when I modify these values.

Maybe at some point in the future, I/we can perform a more detailed analysis behind those scalars and their operation.

 

[rubydist]

This is really interesting reading. The general "rule" for spark advance is that you can add 1.5* for every 2 points of increased octane. So I would expect you could add 4* of timing to the stock tune by going from 87 to 93 octane. My experience is that Ford engineers stay away from knock like the plague, so you could likely add another 2-3* if you really trust the knock sensor is working well. That's likely why the 4* adder is the baseline on the referenced tune.

fwiw, I have yet to see a case where the torque is going down when adding spark advance - it always gets to detonation first, in my experience - but I haven't done any tuning on the SHO motor yet...

 

[Axianator]

This is really interesting reading. The general "rule" for spark advance is that you can add 1.5* for every 2 points of increased octane. So I would expect you could add 4* of timing to the stock tune by going from 87 to 93 octane. My experience is that Ford engineers stay away from knock like the plague, so you could likely add another 2-3* if you really trust the knock sensor is working well. That's likely why the 4* adder is the baseline on the referenced tune.

I agree. I should also note that "the news wasn't all bad" when my factory 3.2L was under the governance of Ted's LPM and 93 octane gas. The increased ignition timing produced a noticeable improvement in off-idle throttle response and low-end torque, while the higher octane afforded me a thicker blanket of detonation protection.

That said, the benefits of this setup did not outweigh the disadvantages, and I was pleased to make the migration to the TwEECer where I could begin to realize my own timing adjustments. The problem with Ted's LPM was that he would add a preset amount of timing to the entire curve, often affecting areas of the spark programming that did not benefit from additional timing. Combine this with the fact that my engine did not respond well to the slow-burning 93 octane gas, and you have the sources of my displeasure.

fwiw, I have yet to see a case where the torque is going down when adding spark advance - it always gets to detonation first, in my experience - but I haven't done any tuning on the SHO motor yet...

I should have probably noted that even with 93 octane gas, I would still experience detonation using Ted's LPM on a hot, Texas summer day. I believe one of the main reasons for this detonation--and the reason why it would apply to any SHO engine--is that, based on our current understanding of the V6 SHO computer programs, the ATX PCM does not remove timing that is added by the global spark adder when the knock sensor indicates activity. The PCM will remove timing that is commanded through other spark tables and functions, but it will not remove the spark that is commanded by the global adders. This is one reason why so many people would experience noticeable and/or increased detonation with their SHO Shop and Ted B. LPMs--the chips were making global changes to the base timing through these individual adder parameters that could not be removed when the engine was knocking, leading to reduced performance.

My personal research and real-world tuning experience have also revealed that, for the most part, the V6 SHO spark programming is already very well optimized for a stock engine. As such, it's not difficult to begin experiencing the reduced power output effect I mentioned in my last post as a result of over-advanced timing.

 

[sho_sc]

Back when I still had my factory 3.2L, I ran--at most--2.5 degrees of added advance via the global adder. Now, I run a set of modified timing tables with only 1 degree of advance through the global adder with my low-comp 3.3L. Very soon, that 1 degree of global advance will be phased out and moved into the appropriate timing tables and adder functions.

Hmm ... I found out the same thing with my LC 3.0L .. about 2.5 degrees seemed the "peepiest". I only use the Global Adder when I am running race fuel or a race fuel mix.


Folks, you need to do some research on MBT (minimum Best Torque for timing). It's not how much timing you can get by with, but the least amount of timing you can get the most power with.

One of these days, I am going to submit a "sticky" on the subject ....

 

[Axianator]

Hmm ... I found out the same thing with my LC 3.0L .. about 2.5 degrees seemed the "peepiest". I only use the Global Adder when I am running race fuel or a race fuel mix.

Interesting, indeed.

Folks, you need to do some research on MBT (minimum Best Torque for timing). It's not how much timing you can get by with, but the least amount of timing you can the most power with.

EXACTLY! Thank you for mentioning the very thing I have neglected to note myself.

Not only that, but the Ford engineer's did us one better by including--in the PCM code itself--the optimal MBT (known in Ford circles as Maximum Brake Torque) values of which Ransom speaks:



Note that although these values are sourced from the D4U1 ATX calibration, they should also apply--in large part--to the MTX calibrations, as well (and in turn, the 3.0L V6 SHO engine). In any case, they show us mortals the maximum amount of spark advance that will produce the maximum amount of power on our engines. They also reinforce my earlier point that the spark programming in the V6 SHO calibrations are already very well optimized for power output from the factory.

IOW, the work has already been done for us.

 

[hawkeye18]

This thread officially makes my head hurt now. What is this latest table? Do we have access to it, o us with our mortal tweecers?

Man, I need to come to your house some day. Road trip to Texas!

 

[Toolman]

God stuff, everyone in this thread gets a thanks from me!!

 

[yamahaSHO]

Thanks for all the thanks

I got like 8 of them in this thread alone:nerd:

 

[Sho Amo]

lets say advanced timing 4 deg, would you benefit by changing heat ranges in spark plugs? either hotter or colder.

also, when nitrous is involved do you need to adjust timing to that also?

 

[yamahaSHO]

Just advancing timing (4* over stock at a given RPM) wouldn't warrant a colder plug. Generally you would want to back out timing with large doses of N2O, but depending on the use, it can help cool a charge if the air is hot to begin with.

 

[38SHO]

to the atx shift point, on my stock d4u1 car it shifted around 50mph at redline....

it pulled good there, and set you up at a good rpm in 2nd......... cause 2nd is a long gear.... I think shifting early, while still might be making more power then running it out to redline... could cause poor performance once your in 2nd gear...... its pretty much the same thing with the 3-4 shift, I always felt it better to completely wind out 3rd, instead of bogging down in 4th...........

 

[hawkeye18]

I have 3rd set to shift into 4th, at max throttle, at 127.5mph. Which means, at max throttle, it will never shift into 4th. At least until I let off the throttle some...

 

[Axianator]

to the atx shift point, on my stock d4u1 car it shifted around 50mph at redline....

I personally doubt that your stock ATX SHO was truly shifting into second gear at 50 MPH. The D4U1 programming puts the 1-2 WOT shift point at 42 MPH, and it would take an extraordinary set of conditions to enable the tranny to shift at 50 MPH under factory programming. Perhaps the tranny was shifting at an indicated 50 MPH, in which case your speedometer (or some related part) was to blame.

In the unlikely event that your tranny was shifting at 50 MPH, then you had other issues that needed addressing.

it pulled good there, and set you up at a good rpm in 2nd......... cause 2nd is a long gear.... I think shifting early, while still might be making more power then running it out to redline... could cause poor performance once your in 2nd gear...... its pretty much the same thing with the 3-4 shift, I always felt it better to completely wind out 3rd, instead of bogging down in 4th...........

When making a WOT run, I agree that holding third gear up to redline will yield the best performance results. However, care must be exercised when forcing the tranny to shift into second gear above 7,000 RPMs. This is why I recommend compromising on a slightly-higher-but-not-too-dangerous 1-2 WOT shift point of about 45 MPH.

 

[hawkeye18]

yeah, having the tranny shift at 48mph at something near 7500RPM with pretty darn line pressures (wham!) probably wasn't real good for the tranny...

 

[38SHO]

yeah maybe my speedo was off,

but from what I remeber

these are the speeds at redline in each of my gears

1st-50
2nd-90
3rd-130ish

 

[SHOZ123]

The actual mph shift will probably be way after of the commanded value. Especially at the 1-2 shift. Are there torque reduction parameters in the TwEECer?

 

[Axianator]

The actual mph shift will probably be way after of the commanded value. Especially at the 1-2 shift.

I disagree.

The factory 1-2 WOT shift speed for the '93-'95 ATX SHO is commanded at 42 MPH, while some here have claimed that their "factory" car was shifting into second at 50 MPH. I cannot think of anything that would cause a repeated ~8 MPH differential between the actual shift speed and commanded shift speeds on a stock vehicle. Even when using the factory TV line pressure values, I have never seen an ATX SHO shift more than an indicated ~2 MPH above the commanded shift speed for each gear change.

Are there torque reduction parameters in the TwEECer?

Yes, although the D4U1 does not contain as many torque control parameters as it's younger '96-up EEC-V siblings. I'm hoping to release at least some of these parameters with the next release.

 

[SHOZ123]

On my '97 I have to set the 1-2 shift point at 38 mph which is .5 mph above the stock setting. At this setting and with stock line pressures on the 1-2 shift the actual shift happens at 50 mph. The mph setting is the only reliable way to get the car to shift at the speed I want as the rpm parameters have little effect.

As I was told this is because things are happening too fast for the processor to get the info and do anything about it in time based on rpm data.