Strange launch control interaction with traction control

[fortressofcomfort]

How'd I miss this? Apparently,at least on my car, if I have traction control turned off (which is every time I get in the car) then launch control does not work properly and will leave you stalled in the middle of an intersection as you spend the most 15 embarassing car seconds in your life trying to get your shitbox restarted. Of course after this happening twice I searched this forum and found nothing on the matter. Note I did use the utility on Cobb's website to setup LC/FFS on the current map I'm using (just the OTS Stage 1 SRI SF TIH 93 V210) but I found no difference setting it up myself in ATR.

Anyway what happens is you get your map all setup and loaded, find some turd to race; you turn off traction control, you floor it at the red light ready to go, revs come up to 3k or whatever, you let the clutch out with a brief slip, and the car just dies completely. Then, you can't just start it up again using the normal method. You have to turn the car off completely, remove key, reinsert, etc. Sucks.

I was able to recreate this every time. Now, by simply leaving traction control turned ON (the default) every time I start the car it performs flawlessly every time.

************************************************** ************

My current settings are as follows (in case anyone gives a rats ass):

FFS Rev Limiter:
- Set to "only" 6,000 rpms. The reasoning is this... Most shifts occur between 5,750 - 6,000rpms. By keeping your foot to the floor between shifts, the FFS Rev Limiter being set at 6,000 rpms will momentarily continue to feed the engine with a small amount of fuel (keeping boost up) but not enough to significantly raise the engine speed which, when unloaded, is a dangerous practice on an unloaded engine.

LC Rev Limiter:
- Set to 2,800 rpms. This is the "nut" number, the make or break value. I have found it better to err on the side of too high rather than too low for 2 main reasons. Reason 1: If the value ends up being too high for your launch conditions, it is easy to mitigate your botched launch by just short shifting into 2nd gear once the turbo starts frying the tires. Sure you'll lose a few tenths in the 60' time but it looks better and is more consistent than a bogged launch :-) and, Reason 2: The hysteresis (resolution) for the LC Rev Limiter is very course in this ECU. For example, if you were to set the LC Rev Limiter to 2,750rpms, you'd see the rpms sometimes go back and forth between as much as 2,500rpms and 3,000 rpms; I've seen the non-adjustable hysteresis for this as bad as 500 rpms. This is quite a bit of variance and it makes it hard to launch the car not knowing if you'll be catching the engine on the "upswing" (fueling) or the "downswing" (throttle closed). If you happen to release the clutch as the engine is on the downswing it is surprisingly easy to fully stall the car or bog terribly especiallly if the track is sticky enough. Trial and error has shown that a slightly high LC Rev Limiter combined with a tiny bit of clutch slip yields the best, most consistent manageable results.

Rev Limiter:
- Set to 6,700 rpms due to stock mechanical limit.

Speed Limiter:
- Set to stock value of 186.41 mph (no mechanical speed limiter).

Speed Limiter Hysteresis:
- Set to stock value of 3.5mph (has no effect unless you actually reach the Speed Limiter :-) )

Vehicle Speed Threshold for LC/FFS
- Stock value is 6.21mph (where the f do they get these numbers, are they initially metric numbers?). I have this changed to 3mph. This means that launch control is essentially disabled after the car hits 3mph allowing for big burnout. Reasoning is this:
- At the drag strip you (usually) have to go through water box necessitating at least a mini burnout to dry the tires (and I believe even radials enjoy a slight heating). By having VSTFLCFFS set at 3mph I can pretty much just dump the clutch even just creeping along whenever and dry the tires. The problem with the stock value of 6.21 mph is that if I ride through the water slowly and then try to force a burnout, LC might be on and limit me to 2,800 rpms or whatever restricting me from doing a 2nd gear (55mph) burnout.
- On the street, it is too easy to get caught off guard by a WRX if the traffic light turns green just as you are about to stop. This means LC will be on forcing you into a pussy launch as the WRX eats your lunch. By lowering VSTFLCFFS to 3mph I have a bit more control as to what I want to do at that split second (get some tire spin or just roll it out)
- Regardless, this setting is definitely a matter of personal preference and I can see some people liking it set as high as 10 or even 15mph if they are just unable to control wheelspin.

[drenkel]

Have not had this problem (Just recently got my AP and have been playing with the LC and FFS)

Works flawlessly for me...

BTW I Have FFS set to 4250 - When you FFS you don't want the RPM's pegged at 6K... 4250 is a good range, because that's about where you will be when you get into the next gear. If you got it pegged at 6K and drop it into the next gear quickly you stress the motor.

I Have the LC rev limiter set to 3500, 2800 diddnt work too well for me. I got pretty sticky tires, and I don't dump the clutch.

For the speed limiter hystersis I have this set to 3.5 as well... don't wanna be stuck in nanny mode once you get going. It's always better to control the wheel spin on your own.

[fortressofcomfort]

LC Rev limiter at 2,800rpms ends up at about 3,000rpms on the tach. I'm sure it varies from car to car.

But with FFS at 4250 doesn't your boost start to drop between shifts kind of negating the purpose of flat foot shifting? I thought the whole point of ffs esp on a turbo car was to keep boost up between shifts. I understand the stressing the motor part but we'd all shift at 2000rpms if engine life was our main goal. Thoughts?

[drenkel]

If your not hitting full boost at 4K RPM's your car is fucked up. There's no reason at all to drop the clutch at 6K RPM's.

[fortressofcomfort]

Originally Posted by drenkel If your not hitting full boost at 4K RPM's your car is fucked up. There's no reason at all to drop the clutch at 6K RPM's.

It was my understanding that if say your FFS is set to 4,000 rpms, and you shift from 1st to 2nd at 6,000 rpms, that, with your foot on the floor, the ECU will close the throttle until the engine hits 4,000 rpms. If the throttle plate is closed I don't see how you can make much boost.

With my old Mustang (I know different beast) I used to FFS (we called it power shifting) so that the engine would hit the rev limiter between shifts.

What am I missing?

[JLuth]

From my experience with FFS, I have it set at 4750 rpm and when I no lift shift the engine loses significantly less boost than if I were to lift to shift. I don't have any numbers to compare right now but know the premise.
Hope that helps.

Crapatalk

[dantes5823]

Someone wanna log a normal shift, ffs with 4750, and a 6k? That'll show us the difference real quick. I myself have my lc at 2700 on stock tires and it works pretty well. My ffs is at 5k and I shift at or around 6k.

[fortressofcomfort]

Originally Posted by dantes5823 Someone wanna log a normal shift, ffs with 4750, and a 6k? That'll show us the difference real quick. I myself have my lc at 2700 on stock tires and it works pretty well. My ffs is at 5k and I shift at or around 6k.

I might try this over the next few days but am busy first part of this week.
Even Braden @ Cobb says 6k ish is the correct number for the FFS limiter.
But god knows you all know I'm a numbers/facts guy, I don't trust no bench racing, so I'd love to see a test like Dantes is proposing. My fear is, with my AP at least, that we won't see much of anything either way. My AP only grabs about 5 data points per second. I bet a quick FFS can be performed in like a half second.
I think the bottom line is we don't want to see the throttle tpp close, or boost psi drop, more than a few tolerant pct, during a FFS. If we do then we might as well lift shift.

[fortressofcomfort]

F. We're def missing something here. Just ran a test and, even with my current FFS limiter set to 6,000rpms, the engine just slams right into its 6,700rpm limiter if u hold the clutch and accel pedal down together (at say 50 mph, simulating a shift to 3rd gear). Now I've gotta figure this shit out. Something tells me this FFS limiter is rather some kind of LOW limit, as if to tell the ECU that any FFS action above this rpm is indeed an attempt at FFS. Cuz setting it to 6000 and thinking it will keep the engine from revving past 6000 rpms just isn't how it works. More to come.

[2k4_8]

I guess I am slow but I set mine to 4950 and if I Ffs I still hear it bounce a couple times. But it definately holds boost vs dumping it all. Imo, no need for 6k when even lower you can still hear the limiter/bpv working.

[fortressofcomfort]

Originally Posted by 2k4_8 I guess I am slow but I set mine to 4950 and if I Ffs I still hear it bounce a couple times. But it definately holds boost vs dumping it all. Imo, no need for 6k when even lower you can still hear the limiter/bpv working.

Not slow. The problem is NONE OF US KNOWS WHAT THIS VALUE (FFS LIMITER) REALLY MEANS OR DOES. If you do please tell us. Until we know what it means and what it does, none of us can say what the correct value is.

And the COBB docs are not correct! They say if FFS conditions are met (vehicle is traveling faster than LC vehicle speed limiter / Vehicle Speed Threshold for LC/FFS and clutch is depressed) then fuel delivery is blocked and other overrun parameters are enabled to keep the engine speed below the value set in the FFS limiter value. This is clearly not happening. Atr docs pg 56

[dantes5823]

Back to the OP's problem tho, i did a tcs off lc burnout just fine yesterday. i was at the car wash and wanted to dry tires. Turned off traction control, hit LC at 27 and dumped the clutch...burn out came as requested.

[2k4_8]

This week I will try and post a vie of how mine is working, because I haven't experienced any issues similar to yours.

[Chimmike]

why are you using LC on the ms3 anyways? just learn how to launch. This isn't a two-step or anything, it's just a lower rev limit if you suck at throttle control.

When you say you turn off traction control, you just hit the button or are you pressing and holding during start to partially disable SWAS?

[Celestspeed3]

Originally Posted by fortressofcomfort It was my understanding that if say your FFS is set to 4,000 rpms, and you shift from 1st to 2nd at 6,000 rpms, that, with your foot on the floor, the ECU will close the throttle until the engine hits 4,000 rpms. If the throttle plate is closed I don't see how you can make much boost.

You won't make boost with this either way, it's not anti-lag. It's just an adjustable rev limiter nothing more. The 1st to 2nd shift has the biggest rpm drop and the engagement of 2nd after gear after maxing out 1st is where you want to have it set at to reduce unnecessary drivetrain wear. I have mine set to 4900rpm. If you set it higher you are relying on the clutch to "pull" the car for _____rpm and this will cause premature wear as per the warning of the FFS/LC. I don't think people want to be doing clutch changes more often then they should be.

Originally Posted by fortressofcomfort NONE OF US KNOWS WHAT THIS VALUE (FFS LIMITER) REALLY MEANS OR DOES.

The FFS limiter is a new rev limiter about the LC/FSS threshold, nothing more. Under the LC/FFS threshold with clutch in the motor uses the LC limter, above the threshold with clutch in the motor uses the FFS limiter, with clutch out in all gears including neutral the motor the standard limiter.

Originally Posted by fortressofcomfort F. We're def missing something here. Just ran a test and, even with my current FFS limiter set to 6,000rpms, the engine just slams right into its 6,700rpm limiter if u hold the clutch and accel pedal down together (at say 50 mph, simulating a shift to 3rd gear). Now I've gotta figure this shit out. Something tells me this FFS limiter is rather some kind of LOW limit, as if to tell the ECU that any FFS action above this rpm is indeed an attempt at FFS. Cuz setting it to 6000 and thinking it will keep the engine from revving past 6000 rpms just isn't how it works. More to come.

The reason why you see this is because the OEM tachs are slow, do not trust it for an accurate RPM display. Use the AP shiftlight for that, or install an aftermarket tach. The car does hold 2800rpm, the tach is just out to lunch. If you don't believe me have you AP display RPM and go for a drive.

Originally Posted by fortressofcomfort LC Rev limiter at 2,800rpms ends up at about 3,000rpms on the tach. I'm sure it varies from car to car. But with FFS at 4250 doesn't your boost start to drop between shifts kind of negating the purpose of flat foot shifting? I thought the whole point of ffs esp on a turbo car was to keep boost up between shifts. I understand the stressing the motor part but we'd all shift at 2000rpms if engine life was our main goal. Thoughts?

See comment above regarding the tach. No the FFS is to make driving the car more fun. What you truely desire is anti-lag. The AP is capable of adding this in. HOWEVER, it causes extremely high EGT's and will wear the shit out of everything. To do anti-lag properly you would need full control of the EGR to help keep combustion temps down.




I think most people assume LC/FFS is anti-lag when it's not. The LC/FFS is just a fun and simple rev limiter, that's all. Anti-lag is what sounds like a machine gun, and makes 20psi of boost standing still, and between shifts.

[dantes5823]

Originally Posted by Celestspeed3 See comment above regarding the tach. No the FFS is to make driving the car more fun. What you truely desire is anti-lag. The AP is capable of adding this in. HOWEVER, it causes extremely high EGT's and will wear the shit out of everything. To do anti-lag properly you would need full control of the EGR to help keep combustion temps down. I think most people assume LC/FFS is anti-lag when it's not. The LC/FFS is just a fun and simple rev limiter, that's all. Anti-lag is what sounds like a machine gun, and makes 20psi of boost standing still, and between shifts.

How would you go about doing this? Just out of curiosity. Not like im gonna hit two step at a red light to show off or anything. And i dont really wanna blow my motor being a tool.

[triplejumper18]

I build boost with AP LC....

[Celestspeed3]

Using the AP's LC will not build boost, you will hear your BPV but that's "fake" boost.

If you are building boost, please supply a log I'd like to see it.


Give ATR a look see. If you know who the anti-lag works you will see how to do it. I don't want to tell because I don't want a blown motor on my conscience if you do it wrong.

[djuosnteisn]

You can build boost with LC, lots of cars do. My buddy's sti builds like 10psi at the strip. And IIRC anthony (superskater) used to build a significant amount as well.

The throttle plate is open, the turbo is spinning, and boost is possible.

[triplejumper18]

http://www.mazdaspeedforum.org/forum/foru...-lc-ffs-90471/

"COBB Tuning is pleased to announce the availability of Launch Control and Flat-Foot Shifting for 2nd Gen (2010-2011) MAZDASPEED3s. Launch Control limits engine RPM to a user-set value when launching to build boost and increase launch consistency."

[Chimmike]

A-la brake boosting?

yeah, 2 step=basically retarding the shit out of ignition timing iirc moving the combustion event into the turbine itself.

[silvapain]

I'm not reading all the posts above. My opinion is more important than everyone else's in here anyways (except for my <3 Dustin. Kisses).

COBB FFS/LC pulls fuel to lower RPM (OE rev limit strategy). A true 2-step retards timing.

Disable FFS/LC. Buy N2MB WOT Box.

[djuosnteisn]

My <3 silva


Yup, wot box cuts spark... which is basically like super retarding it lol. But even with the AP's LC strategy, you can still build boost.

I think the amount of boost will depending on the LC rpm as well.

PS, i still use a wot box in my ms6, for the exact reasons silva mentioned.

[2k4_8]

Originally Posted by Celestspeed3 Using the AP's LC will not build boost, you will hear your BPV but that's "fake" boost. If you are building boost, please supply a log I'd like to see it. Give ATR a look see. If you know who the anti-lag works you will see how to do it. I don't want to tell because I don't want a blown motor on my conscience if you do it wrong.

It doesn't build a ton, but 2 psi is better than a vacuum on the launch and I supplied a FFS log to show that it holds at 5 psi or greater instead of dumping into a vacuum when you shift too. I have LC at 2950 due to street tires, and it will build a little more at 100% throttle position, but i don't see the point in launching under full power when it will never keep any traction. TC kicked in even on this soft launch so that's why it is building boost so slowly in the log. I know it's not like anti lag, but it is what it is.

[Celestspeed3]

Sweet thanks.


I have mot been able to build boost with LC my FFS looks the same as yours. But my LC is also set lower than yours maybe that's why.


DJ, what WOT box are you using?

[Paul]

Originally Posted by chimmike why are you using LC on the ms3 anyways? just learn how to launch. This isn't a two-step or anything, it's just a lower rev limit if you suck at throttle control. When you say you turn off traction control, you just hit the button or are you pressing and holding during start to partially disable SWAS?

this button holding work for gen2 ?

[Chimmike]

Originally Posted by Paul this button holding work for gen2 ?

It should, but I would also disconnect your SWAS. shit is invasive.

[Paul]

Originally Posted by chimmike It should, but I would also disconnect your SWAS. shit is invasive.

yeah but then when I try driving slow in a parking lot all of a sudden the electric power steering says fuck you!

Ive disc. SWAS when I was having @phate tune me, It gave me MOAR power in the lower gears... Torque to be exact... + lifted boost cap. With @jbarone 's 80 Duo Trilogy mounts there should not be any significant torque steer.... Not that torque steer ever was hard to control for me .. in fact it made it fun in a dangerous way.

Come to think of it I should have taken that shit off when I went to the drag strip.... Oh Well I will go there when I get my 17x9 with 245/40-17s less wheel weight and moar grip MOAR POWER *(@#&(@*#(@*#.

[inglouriousbasterd]

It's pretty funny using the traction control with launch control , it'll let me smoke the shit of tires for a few feet then kicks in and feathers the throttle for me , but that's for lazy people.

[triplejumper18]

Originally Posted by Celestspeed3 Sweet thanks. I have mot been able to build boost with LC my FFS looks the same as yours. But my LC is also set lower than yours maybe that's why. DJ, what WOT box are you using?

I have LC at 4500rpms and I've seen as much as 5+psi when I've launched but I have not waited to see what the max PSI is.

[djuosnteisn]

Originally Posted by Celestspeed3 Sweet thanks. I have mot been able to build boost with LC my FFS looks the same as yours. But my LC is also set lower than yours maybe that's why. DJ, what WOT box are you using?

Sorry for late reply.... i'm using the N2MB wot box:
WOT Box - N2MB Racing

Fairly simple install, not sure if ECM pin out is the same on gen pu as it is on gen done... but might be close enough. If you have a manual it'd be simple to verify.

[Celestspeed3]

I had a chance to reviewmthe logs and as silly as this is, I wasn't holding my foot to the floor during launching. I would just push it down enough to hit the limiter. My car makes about 3psi if I floor it.

[fortressofcomfort]

Originally Posted by inglouriousbasterd It's pretty funny using the traction control with launch control , it'll let me smoke the shit of tires for a few feet then kicks in and feathers the throttle for me , but that's for lazy people.

I completely agree. But read my original post. My car is literally buggy if both LC/FFS is enabled, TC is off, and LC launch is attempted. Full fuel cut and stall. Something is just not right. I have run 1.8 60' times in drag radialed 2002 Mustang GT and 1.9 60' times in 22" slicked 2.0L naturally aspirated 1997 Neon so please don't call my driving skills into question.

I HAVE however not worried so much about FFS. I just hold right foot to floor, shift at 6k, and complete shift quickly. Shift is completed by 6700 unless missed. I really don't think I will blow the motor occasionally hitting the 6700 rpm limiter.

So I guess above all TC must be disabled for spirited driving then I'm gonna have to do like silvapain says and disable LC/FFS. Too bad. It does make launching easier in this car but I guess I will just have to man up on one more skill.

Maybe if someone local like Will wants to stop by one day to make sure I'm not hallucinating that would be good.

[2k4_8]

Originally Posted by fortressofcomfort I completely agree. But read my original post. My car is literally buggy if both LC/FFS is enabled, TC is off, and LC launch is attempted. Full fuel cut and stall. Something is just not right. I have run 1.8 60' times in drag radialed 2002 Mustang GT and 1.9 60' times in 22" slicked 2.0L naturally aspirated 1997 Neon so please don't call my driving skills into question. I HAVE however not worried so much about FFS. I just hold right foot to floor, shift at 6k, and complete shift quickly. Shift is completed by 6700 unless missed. I really don't think I will blow the motor occasionally hitting the 6700 rpm limiter. So I guess above all TC must be disabled for spirited driving then I'm gonna have to do like silvapain says and disable LC/FFS. Too bad. It does make launching easier in this car but I guess I will just have to man up on one more skill. Maybe if someone local like Will wants to stop by one day to make sure I'm not hallucinating that would be good.

It's wierd how we have so many strange and buggy interactions with the ecu. Mine definately doesn't do what yours does, but I believe you that yours is wiggin out.

[fortressofcomfort]

Originally Posted by 2k4_8 It's wierd how we have so many strange and buggy interactions with the ecu. Mine definately doesn't do what yours does, but I believe you that yours is wiggin out.

Hey is yours a 2012 ? Cuz it appears we have the same exacts mods. How'd you setup your map? All I did was use the stock Stage 1 + SF + TIH 93 v210.ptm, send it through the LC/FFS utility on the website (with 2800 rpm LC, 6000rpm FFS), then adjust the LCFFS Vehicle Speed Threshold from default of 6.21mph to 3mph in ATR. Nothing fancy.

Also I have posted the basic contents of this thread along with my current .ptm over at http://www.cobbforums.com/forums/for...77-Mazdaspeed3 so hopefully Braden will verify everything is setup correctly and I didn't screw something simple up.

[2k4_8]

Originally Posted by fortressofcomfort Hey is yours a 2012 ? Cuz it appears we have the same exacts mods. How'd you setup your map? All I did was use the stock Stage 1 + SF + TIH 93 v210.ptm, send it through the LC/FFS utility on the website, then adjust the LCFFS Vehicle Speed Threshold in ATR. Nothing fancy.

I am 2010 and using the CS SRI +TIP stage one, all I did was change to buckers atr cheat sheet recommendations and then adjust the lc/ffs limiters in atr. I honestly don't know what to say but it's kind of like how some folks can't use boost tuning on their ecu I guess? Why did you change the threshold? I left mine at 6.21 mph LC 2750, FFS 4950.

[fortressofcomfort]

Originally Posted by 2k4_8 I am 2010 and using the CS SRI +TIP stage one, all I did was change to buckers atr cheat sheet recommendations and then adjust the lc/ffs limiters in atr. I honestly don't know what to say but it's kind of like how some folks can't use boost tuning on their ecu I guess? Why did you change the threshold? I left mine at 6.21 mph LC 2750, FFS 4950.

Grrrr every time I see CS I think "CobbSport" instead of "CorkSport." Duh. Anyway I think that is my next step... to just go with some known good numbers and try again.

I have also applied Abilor's and Bucker's tuning recommendations separately in the past. Both are gains, Bucker's really rips esp with those ignition timing maps of his, but I just get too much noise (knock) and high BATs with their tunes. They are good tunes but just really on the edge and require only the finest of dino juice in the tank. I'm too cheap and I need a tune that works with pretty much any 93 octane around, and I don't want any noise, so I have chosen to stick with Cobb's OTS stage 1 stuff. I'm happy with 300ish at the crank for now. Whatever works. Boost tuning isn't the issue.

[fortressofcomfort]

Originally Posted by chimmike why are you using LC on the ms3 anyways? just learn how to launch. This isn't a two-step or anything, it's just a lower rev limit if you suck at throttle control. When you say you turn off traction control, you just hit the button or are you pressing and holding during start to partially disable SWAS?

Just pressing the TC button. What does holding it down do?

[2k4_8]

Originally Posted by fortressofcomfort Grrrr every time I see CS I think "CobbSport" instead of "CorkSport." Duh. Anyway I think that is my next step... to just go with some known good numbers and try again. I have also applied Abilor's and Bucker's tuning recommendations separately in the past. Both are gains, Bucker's really rips esp with those ignition timing maps of his, but I just get too much noise (knock) and high BATs with their tunes. They are good tunes but just really on the edge and require only the finest of dino juice in the tank. I'm too cheap and I need a tune that works with pretty much any 93 octane around, and I don't want any noise, so I have chosen to stick with Cobb's OTS stage 1 stuff. I'm happy with 300ish at the crank for now. Whatever works. Boost tuning isn't the issue.

Ya, I agree with everything you said, I may drop back to straight stage one with bucker tweaks and leave boost and timing ots.

[triplejumper18]

Is your AP and ATR up to date?