Boost by gear or boost by MPH

[ATS4me]

After running a number of different tunes on my ATS, I've learned the hard way that boosted cars are more sensitive to load than NA V-8. In 2nd gear, I can run some pretty high g/cyl and have TQ spikes hit 400 ft-lbs and not have any knock. Once the car hits 4th gear, the load is to great and the tune becomes knock central, even with lower timing. What would be prefect would be a table with speed and mph on the X/Y axis and a multiplier that adjusted knock airmass. At high speeds and low rpms, the table could use a multiplier of less than 1 to reduce knock airmass to a safe level. Is there any table that will adjust either knock air mass or boost based upon speed or load?

[cobaltssoverbooster]

for some reason i cant read the available posted ats file to look for a table. i do know in the lnf we have a desired load plot on rpm x gear axis. hopefully you guys have something the same in the ats. 100 is desired max load output anything less turns traction control on limiting boost.
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[ATS4me]

Thanks! I'll look for the RPM v Gear table tonight.

It looks like the description states "...whilst the TCC is locked." Is the locked TCC just for the Max TQ vs RPM table? The RPM vs Gear table is the home run table if the TCC can be unlocked.

[ATS4me]

I looked at every entry under TQ management and no luck. The RPM v. Gear Table is not there. Even looked at the trans TQ management to see if it was hiding in there.

[cobaltssoverbooster]

dang that would have been cool though

[S2H]

I think you are going about this the wrong way...

is it actual knock???
or is it just calculated knock....
because if its just calculated torque and knock....it doesnt mean jack....

you need to tune for best power, not calculated knock


the table that determines spark is your High and low octane timing tables...
the amount of air/Fuel is determined by the MAF/VE tables.

boosted vehicles are not more sensitive to load......boost is extra load....boost creates load.
so as load goes up you need to reduce timing.


that calculated torque is used by the pcm to determine transmission things....it is not accurate at all when the tune is not correct.
you need to stop worrying about the torque # the ECU spits out and start tuning.
stop putting in different tunes....you dont use other peoples tunes...
you make changes to your tune based on data you collect in the scanner and with a wideband.

the E39a which is the ECU in your car is basically the same as an E38...except yours has a couple of extra tables(of which you will probably never need to touch)


the "torque Spikes" hitting 400 in one gear and not doing any "knock" vs a different gear and it does do "knock"...is not knock at all...its spark removal for torque management to keep the transmission alive.
it is timing retard...not knock
if your tune is off..that value will report quite drastically incorrect and the transmission will have a much shorter life as that torque value is calculated based on the tune.

[ATS4me]

S2H, I don't understand what prompted such a harsh post, but obviously I'm not copying anyone's tune because there are no ATS tunes in the repository or posted on here other than my stock tune. I've looked at the 1.4l and Cobalt tuning threads for ideas since the PCM tables are similar, but nothing has been copied.

To see if I'm making more power, I log engine torque, g/cyl, and MAF rate. I use g/cyl as the more important measure because it ties into the high octane spark and knock airmass tables.

I'm not sure what calculated knock is. I log knock retard and timing. As far as I can tell after knock retard goes over about 2, timing starts getting pulled. At about 4* of KR, g/cyl, boost, and desired boost all drop significantly, which makes sense given how the knock airmass table is set up. I have tried reducing timing at higher g/cyl levels and also tried adding a little more fuel in areas where this pops up.

What I've found is in the 2500 - 4000 rpm range, I can run a higher g/cyl in 2nd gear w/o knock than I can in 4th gear. If you can help me understand what might be off, or what to look for that would be useful.

[ericemir]

I dont think he was harsh I feel he was more real... if you arent careful serious engine damage can occur. Almost everyone in here is very helpful and everyone wants to help someone... dont take such responses as harsh people are just want to make things clear of what you may be doing wrong... I dont know S2H personally but I dont find it harsh.... Just saying.

[S2H]

S2H, I don't understand what prompted such a harsh post, but obviously I'm not copying anyone's tune because there are no ATS tunes in the repository or posted on here other than my stock tune. I've looked at the 1.4l and Cobalt tuning threads for ideas since the PCM tables are similar, but nothing has been copied.

To see if I'm making more power, I log engine torque, g/cyl, and MAF rate. I use g/cyl as the more important measure because it ties into the high octane spark and knock airmass tables.

I'm not sure what calculated knock is. I log knock retard and timing. As far as I can tell after knock retard goes over about 2, timing starts getting pulled. At about 4* of KR, g/cyl, boost, and desired boost all drop significantly, which makes sense given how the knock airmass table is set up. I have tried reducing timing at higher g/cyl levels and also tried adding a little more fuel in areas where this pops up.

What I've found is in the 2500 - 4000 rpm range, I can run a higher g/cyl in 2nd gear w/o knock than I can in 4th gear. If you can help me understand what might be off, or what to look for that would be useful.

I dont know what you are taking as harsh....nothing in my post was harsh or degrading in any way...






Not all OS's treat Knock retard as only real knock retard...some OS's report knock retard for ANY timing reduction anywhere in the tune...because its actually techincally "Timing Retard" which encompasses all timing related retard
so what I'm trying to tell you, is that you cant just log knock retard and expect it to be useful...
If you see "knock retard"...then its telling you its pulling timing
you say "when it goes over 2 it pulls timing"...if it goes over 0 it is pulling timing...it doesnt have to get toa certain number to pull timing...if it reports a value of more than 0 IT IS PULLING TIMING...
that knock retard...can be a calculated knock (such as burst knock, tip in knock, torque management)
it doesnt mean you necessarily have actual real world knock....it could just be computer math.

anytime you pull timing, for any reason, whether it is knock related or just timing not being high enough, you will see a drop in boost as the engine looses efficiency. ...
people use timing to keep boost in line all the time or to keep it lower for launch...
its a natural relationship between the two things.
its also why as you tune for more boost, you have to pay attention to timing...often your engine can handle a lot more boost, but it cant handle the timing along with it...and timing will push the boost up...add 2* and you will see a rise in boost or how fast it gets to max boost....take away 2* and it slows it down

the next thing...
logging engine torque...
the value that is reported as engine torque...is not actual engine torque..
its a calculated value made up by the PCM...
it was designed to allow the ECU to determine when the engine is making too much power for the crappy stock transmissions and then it would allow it to use "torque management" to pull some timing at various times to protect the life of the transmission.
that torque value you are looking at in the scanner...because it is calculated...is going to change anytime you change something timing or airflow/fueling related in the tune...part of its calculation involves cylinder airmass..which again, is effected by timing and Airflow/Fueling

so what I am saying is...to not try to use that "calculated torque" value for tuning....it will lie to you like a woman after a night out at the Club with her girlfriends.
its also related to the MAx torque timing table in many OS's...
I can fake the number out by changing the values in the Max timing table which doesnt do anything except for provide numbers for that torque calculation.....


also, if "desired boost" drops...actual boost should drop as well... that means the ECU is doing its job and commanding the Wastegate to open a little to keep boost down.
when the ECU see's knock, it thinks its boost related or spark related....
it decides which way to go based on other parameters in the tune.

also..being able to run a Higher g/cly (a higher load) in 2nd vs 4th is because its got a better gear ratio in 2nd...
it takes less force to move a heavy ass car in 2nd than it does in 4th....so you will get less knock in 2nd than you will in 4th

its best to tune for the harder load(4th gear) and then you dont have to worry about the lower gears.

also...lastly...
post your tune
if we cant see whats going on, we cant really help.
and if theres no tune in the repository...then we cant download a generic file to look at what you are talking about.

[ATS4me]

also..being able to run a Higher g/cly (a higher load) in 2nd vs 4th is because its got a better gear ratio in 2nd...
it takes less force to move a heavy ass car in 2nd than it does in 4th....so you will get less knock in 2nd than you will in 4th

its best to tune for the harder load(4th gear) and then you don't have to worry about the lower gears.

I guess I did not explain it well. That's all my original post was about. Tuning for harder load (i.e. 4th) forces me to run lower g/cyl to avoid knock in 4th that is not present in 2nd. The rpm by gear table for the lnf would do exactly that. I could tune 2nd to its max potential and then step it down in the higher gears.

I've been looking at the gains being advertised by "professional" tuners. They're lower through the midrange than I was trying to achieve. Maybe it was for good reason; I may have found the limit w/o going to a colder plug or meth.

Peace.

[S2H]

I guess I did not explain it well. That's all my original post was about. Tuning for harder load (i.e. 4th) forces me to run lower g/cyl to avoid knock in 4th that is not present in 2nd. The rpm by gear table for the lnf would do exactly that. I could tune 2nd to its max potential and then step it down in the higher gears.

I've been looking at the gains being advertised by "professional" tuners. They're lower through the midrange than I was trying to achieve. Maybe it was for good reason; I may have found the limit w/o going to a colder plug or meth.

Peace.

this brings up the question.....
have you even looked at your plugs??? made sure you have the right heat range? made sure about how much timing you are putting into it??
the plugs will not lie....knock sensors lie all the time.

[ATS4me]

The plugs are factory 2.0T plugs. The car only has 3k miles on it and I needed some break-in miles before I started to experiment so nothing has been changed.

The factory timing table's last row was 1.36 g/cyl and stock the car is breathing about 1.1 to 1.2 g/cyl in the midrange. I'm trying to run 1.5 g/cyl to 1.6 g/cyl. I have tried reducing the 1.36 g/cyl row by 1* and 2*. I also tried adding a small amount of fuel in the midrange. I haven't tried reducing it by 3*. With 2* reduction in timing, I'm already negative at parts of that rpm range.

Right now, I'm thinking the motor will be fine in the 1.4 to 1.5 g/cyl in the midrange. I just need to walk it back a bit. With an automatic, it's hard to be at WOT in the midrange in higher gears, so my focus is really on the top end. IMO, the factory tune is deliberately weak on the top end to avoid competing with the V6 upgrade.

[S2H]

how about we talk in terms of boost....
Grams per cylinder is calculated...so it can vary based on many things...

How much boost does it do stock? and how much boost are you putting into it


POST A TUNE AND A DATA LOG...please.