Ratioing down the airflow values. HELP !!!

[GETUSUMM]

Will ratioing down the airflow values to gain more range on maf and ifr, & spark axis range, cause the A6 transmission to have shifting issues? We think that it is making the tranny slip. When we install a non-rationed down tune, the car shifts just fine. If so, what can be done to fix this issue. Thanks

the car is a 2006 vette

[Chris@HPTuners]

the transmission uses calculated torque as its primary means of controlling the shifts.

the ECM uses airflow as it's primary means of calculating engine torque.

So yes, if you reduce the airflow numbers the shifts will get weak. This is the same for most PCM's from the LS1 right thru to the newer stuff.

Chris...

[RWTD]

Chris,

That's exactly what I figured.

If you wouldn't mind adding a bit more, what areas of the trans should we ratio in order to overcome this? Without being able to rescale IFR and the airflow values, he'll peg nearly every limit in the pcm. Since we cut the IFR and airflow values exactly in 1/2, my assumptions would be to rescale all the shift pressure tables. i.e. let's look at the "Base Shift Pressure 1-2 Pattern X" table:

	0	150	300	450	600
-30	700.0	1000.0	1100.0	1400.0	1400.0
-10	700.0	1000.0	1100.0	1400.0	1400.0
20	400.0	700.0	700.0	1400.0	1400.0
30	400.0	700.0	700.0	1400.0	1400.0
125	400.0	700.0	700.0	1400.0	1400.0

The top Axis is in Nm, so by ratioing everything by 1/2, the pcm now sees 600 as 300, 300 as 150, etc. Actually, at least on the E40, I just noticed that the Axis labels are able to be re-normalized for the trans pressure tables, so that would make this a little easier to address, if I'm thinking about this right. i.e. instead of 0, 150, 300, 450, 600 for the axis values, they would end up being 0, 75, 150, 225, 300. Right? Or would just effectively doubling the pressure values be okay (I wouldn't think so)?

A lot of work, since there are TONS of parameters for the A6. It looks like at least the "Base Shift Pressure Upshift - X" and "Base Shift Pressure Upshift - Y" tables need to be renormalized, since the "Pressure Pattern Select" scalars all suggest either X or Y is used, not Z.

Man, what a LOT of work on the A6 vehicles. There isn't a simple scalar that could be modified in the calibration that effectively doubles the pcm's torque calculation (or whatever multiplication needed based on whatever ratio was originally used to rescale the IFR and airflow values)? Thoughts?

Thanks!

[GETUSUMM]

Bump

[Chris@HPTuners]

it *may* work, but honestly the A6 is is so complex that other areas may need to be tricked, or even cannot be tricked (like physics based formulas). I know that the GM calibrators require the engine torque cal to be within something like a 5% tolerance, so your mileage may vary...

[GETUSUMM]

I tried it. I doubled it and cut it in half. It did not work

[RWTD]

So basically, no matter what, on higher powered A6 vehicles, one will never be able to tune the higher flow MAFs properly (like the PowrMAF) without having the MAF hack in there, like you've done with the 2.5 bar system, otherwise, without being able to ratio down, you'll peg the pcm limits for the MAF and areas like spark axis airflow ranges. Even if you get the 2.5 bar soon for the '06 C6 A6, the only bad thing is that the IFR issue is still not addressed, so for properly tuning the 60# injectors (thanks to eficalibrator, we now have the proper values for them on GMs) this issue will still apply.

I guess what I'm saying, is that this is a big issue for the A6 vehicles, because basically on car's like his the torque calculations will never be right when trying to tune everything "properly", with the current pcm limitations, thus the shifting will always be erratic, that is unless you can get the 2.5 bar applied for the car, and the IFR limit raised. It may never even be really right on vehicles that you hack the IFR and PE tables, since then torque calculations will still be off.

It would just be really nice if there was a way to alter the torque reading going into the trans.

[Chris@HPTuners]

ya maybe there is some way to scale the airflow used by the torque calc or the raw torque number, i dunno but that would seem the easiest way to untrick it.

the IFR patch is still possible it's just a lot of work on top of what already is a lot of work for 2bar.

i have this vision of a dog chasing it's tail...

[GETUSUMM]

Welcome to my world

[GETUSUMM]

Would a speed density tune help out? If so, what would it take?

[Chris@HPTuners]

SD is the answer on the airflow side, not sure if i've added support on your OS though.

[vettetech]

hello,
I don't post much but I somehow got involved here. We pull the tranny out and all the clutchs were scorched. after waiting forever to get GM to resign the agreement with the plate venders we got the parts in and put the unit together. It was not well from the time I move it out of the stall. I new something was wrong the the pressure and did a fast learn procedure it did not help. I pull the tcm out and notice all the solinoids were over heated and ousing plastic?! I put a new one in and it got somewhat better. I new it had something to do with the programming. When he told me that the air flow table were cut in half to compensate for the extra air flow caculation i new the information being sent to the tcm was sckewed. is it nessasary to 1/2 everything? what about cut it 20% or so. just what you need. I really don't understand why the solinoids look the way they did. there is much to be learn about whats going on in the tcm. If there was a way to add a calculation to compensate for false load. I going to see if I can get a old freind at GM to do some digging for me.

[GETUSUMM]

I would like to thank all you guys for your time and help with this. Is there a solution to my problem or is going back to the LS2 maf the only answer? From what I am understanding, that is not the right way to do it. What are all these 650plus rear wheel A6 cars doing? What are my options?

[eficalibrator]

The top Axis is in Nm, so by ratioing everything by 1/2, the pcm now sees 600 as 300, 300 as 150, etc. Actually, at least on the E40, I just noticed that the Axis labels are able to be re-normalized for the trans pressure tables, so that would make this a little easier to address, if I'm thinking about this right. i.e. instead of 0, 150, 300, 450, 600 for the axis values, they would end up being 0, 75, 150, 225, 300. Right? Or would just effectively doubling the pressure values be okay (I wouldn't think so)?

That's where I would start - ratioing the torque values on the transmission axes rather than just skewing pressure at what is known to be an incorrect (unscaled) axis value.

You may still need to adjust the pressures (or other trans parameters) after ratioing the torque axes. Don't expect it to be a single step process, and the trans may still need some very serious hardware changes to keep up with the very real increase in actual torque from a supercharged engine.

[beefcake]

well,

dan spent about 3 hours or so tuning my car today, normal like he does on all cars, the trans flaring issue is gone, and there was no need to play halfsies on anything

he did say he thinks my trans is hurt at wot though from the previous tune

btw, i have an 08 a6 vortech, with livernois stage 1 cam

it's like i drove a new car home

so, we got bad tunes eating trannies up all over the place

[RWTD]

First off, thanks for your reply, Greg.

is it nessasary to 1/2 everything? what about cut it 20% or so. just what you need.

Steve, in order to get around the 63.5# injector table limit when using the big 60# injectors , one would need to ratio down by exactly 20%, since the 60# injectors flow from 72.3x to 79.2x # on a GM. I've done this before (ratio down by only 20%), but one issue here is on the GM vehicles with a hard limit of 512 g/cyl on the MAF table, you'll generally hit that limit on the blown vehicles, therefore then you have to start raping the PE table in order to finish the fueling in the upper rpms (i.e. above 5.5k or so). In actuality, I ran this by Roddy a few days ago in discussing this with him, and I told him that it may be the best thing to do.

I would like to thank all you guys for your time and help with this. Is there a solution to my problem or is going back to the LS2 maf the only answer? From what I am understanding, that is not the right way to do it. What are all these 650plus rear wheel A6 cars doing? What are my options?

Roddy, again, it's NOT the MAF. If you go back to the LS2 MAF, you're going to peg it, (around the 475 to 500 rwhp mark), and you'll STILL have the IFR limit issue, period. The new slot style MAF you're using (from the LS7/LS3/LS9) basically won't peg (well, it has it's limits too, but you're far from them, especially in the large housing it's in on your car).

well,

dan spent about 3 hours or so tuning my car today, normal like he does on all cars, the trans flaring issue is gone, and there was no need to play halfsies on anything

so, we got bad tunes eating trannies up all over the place

beefcake, you can't classify them as all bad tunes. My tune isn't bad (none of my tunes are, as I tune properly). It's just that we're all now starting to dig further into an issue that was bound to surface, and now we're all starting proper dialog on it in hopes of resolving it.

Now, with that being said, here's something you may not realize, but your '08 has a MUCH higher MAF table limit than the previous vehicles, so you'll basically never peg it (instead of 512 g/sec, it's 4000 g/sec, and instead of a table range of 12+k Hz, it's 15k Hz). The previous vehicle mentioned here is a different story than yours.

However, something to note, regardless if God is tuning your car or not, unless some ratioing is applied, the big 60# injectors (which flow approx. 73# on a 4-bar GM system, which is what your car has) will NEVER be able to be tuned in properly, since there is a 63.5# limit in the pcm in ALL GM pcms up to the 2008 model year. Only the '09+ LS3 (what Greg [eficalibrator] has) and LS9 vehicles have double the limit (127# limit - I'm sure there are other new '09 vehicles that have this, as well).

So what does this prove? Yes, even YOUR torque values being reported to the trans are skewed, due to the fact that he would have had to rape the MAF in order to absorb the incorrect IFR values for your injectors. I can also bet you that he doesn't have the correct values for those 60s on a GM (eficalibrator is the only one who does, which he kindly lent me ). When I say correct values, I mean ALL of the various injector values that are needed in order to properly control them.


So now back to Roddy, and others who will run into this:

The real answer would be to wait for Chris to apply the 2.5 bar hack to other E38 pcm systems (he just did for my '08 Z06, so I'm very thankful for that). This would give us basically the same MAF range as the '08+ LS3 and LS9 vehicles. However, there's still the issue with the IFR limit. Chris said he can overcome that, but that's going to take additional time for him. So, it's either a waiting game, or basically trying the 20% ratio on Roddy's '06, and hope that's enough to keep the MAF table from pegging, and to allow his trans to function properly.

Regards,

James

[beefcake]

by bad tune, i mean a tune that caused the tranny flare and ate the transmission

the half rationing is what caused my problem and thus caused my tranny to be hurt

my car ran perfect, put the s/c on, had it tuned and the tranny instantly was "bad"

the wear and tear from trying to figure out the problem has taken it's toll,

i wasted a bunch of hours running to the dealership, money replacing a tcm, when it was a simple matter of tuning

from talking to rowdy, it appears his s/c was put on, car was tuned with the same "halfsies" and he lost his tranny too, it's obviously not coincedence

i guess everyone has there way to tune, but if the car runs right the way it's tuned now and everything is working the way it's supposed to, it must be right???

[RWTD]

i guess everyone has there way to tune, but if the car runs right the way it's tuned now and everything is working the way it's supposed to, it must be right???

No, it doesn't mean the tune is really right. Like I said before, most likely you too have the 60# injectors (aka 73.x on GM 4-bar [58 psi] system). Therefore, there's some "ratioing", or either some MAF table raping, in order to get around the IFR limititation on your car. So this means that your TCM is not being reported the correct estimated torque values from the PCM. So, with that being said, although your trans "feels" fine now, the tuning you have could be taking a toll on the transmission, just not at as much an accelerated rate (that was a tongue twister). Hence why I mentioned above that hopefully only 20% ratioing on Roddy's car will allow us to get enough range on the MAF table in order to keep from pegging the MAF measurement, and to also allow the trans to function as well as you are stating yours is now.

[beefcake]

No, it doesn't mean the tune is really right. Like I said before, most likely you too have the 60# injectors (aka 73.x on GM 4-bar [58 psi] system). Therefore, there's some "ratioing", or either some MAF table raping, in order to get around the IFR limititation on your car. So this means that your TCM is not being reported the correct estimated torque values from the PCM. So, with that being said, although your trans "feels" fine now, the tuning you have could be taking a toll on the transmission, just not at as much an accelerated rate (that was a tongue twister). Hence why I mentioned above that hopefully only 20% ratioing on Roddy's car will allow us to get enough range on the MAF table in order to keep from pegging the MAF measurement, and to also allow the trans to function as well as you are stating yours is now.

it feels 100 times better now, except for the damage that was done to it already

it doesn't feel stupid anymore and i don't have to fear an upshift or downshift

i'm not sure exactly what dan does to tune the car, but he said the maf was not pegging on the car anyway as far as that goes, as far as the injectors, i do not know

[RWTD]

The MAF basically won't peg on the '08+ C6. It would take around 1500 rwhp with one of the aftermarket CAIs with the big MAF housing to peg it. The IFR table on the '08 is another story. The limit is 63.5 #/min, and the injectors you are using flow from 72.3x to 79.2x # on a GM , so he's having to absorb the difference (basically 25%) in the MAF transfer. That means your estimated torque values are being reported incorrectly to your TCM by that amount, on top of whatever difference, if any, from the rest of the injector values that may not have gotten inputted correctly (if you don't have all the injector values correctly, then they aren't going to function 100% properly, thus there will be more for the MAF transfer to absorb).

So, like what I said last time, I'm going to ratio Roddy's by 20%, so we can stay within the IFR limit. Since you're trans is doing "decent" at a roughly 25 or more % error on the reported torque estimation, then what I'm doing should work just fine on Roddy's car.

Trust me, other "tuners" didn't know about this with the trans issue with the ratioing. It's something that was basically just brought to light, as there really weren't any other tuners, besides a few of us, that even grasped the whole ratioing concept (tho many more know of it now).