GT Stall Prevention?

[BmacIL]

Not just from a stop, though that's probably when it's most noticeable.

"Stall-saver" routines have been incorporated into EFI systems since the days of idle air motors on much simpler speed-density systems. Even on aftermarket S-D systems.

Nominally, the reason is to keep large suddenly applied load demands on the engine from stalling the engine when at a full stop. Such as from shifting an AT into gear, A/C cycling or adding to the alternator demand (rear window defogger, seat heaters, headlights, etc.).


Norm

Yes, all true, Norm. My point was that this isn't dumb logic. An engineer at Ford spent some time working out and tuning the when and how much for this in order to make it smooth and seamless. It is quite literally, part of what's referred to as Features Calibration. The fact that most MT cars have it doesn't excuse that fact. I have driven several cars with much less intervention off-idle and that require more throttle to get the car going. That's all in the OEM's calibration tuning.

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[Norm Peterson]

Even ones with carbs and no computer. ICEs have to idle and they are making power at idle even if it's only a little.

The difference between a carbureted engine and an EFI'd engine is that the carb engine cannot by itself increase the amount of power that it's making at idle. It has no way of increasing airflow (and from that, making more power) all by itself, which is exactly what EFI stall-saver routines are accomplishing here.


Norm

 

[MadCow]

The difference between a carbureted engine and an EFI'd engine is that the carb engine cannot by itself increase the amount of power that it's making at idle. It has no way of increasing airflow (and from that, making more power) all by itself, which is exactly what EFI stall-saver routines are accomplishing here.


Norm

If the parking brake is applied, the car put in gear, and the clutch fully engaged the motor will stall no matter what the computer tries to do. I'm not sure what the argument is here.

 

[Norm Peterson]

That EFI can actively increase the amount of power available at and around idle rpm with the throttle in its closed position. Unlike most carbureted engines that can only make a fixed amount of power under closed throttle conditions (google "constant velocity carburetor" for an exception).

Even ones with carbs and no computer. ICEs have to idle and they are making power at idle even if it's only a little.

Norm

 

[Norm Peterson]

Yes, all true, Norm. My point was that this isn't dumb logic. An engineer at Ford spent some time working out and tuning the when and how much for this in order to make it smooth and seamless. It is quite literally, part of what's referred to as Features Calibration.

Agreed and understood, especially the "spent some time" part. I'll have to go dig up my old Accel/DFI documentation because I'm positive this was mentioned in there somewhere.

I guess because "features" is such a buzz-word these days that almost anything gets to be called that just to sound "new and improved".


Norm

 

[15wile]

I assure you, it is possible to stall this car.

Related note: don't try to teach your wife to drive stick in a 435hp car.

 

[fcarpio]

I'm driving an auto and looking to go stick within the next couple years. I wanted to clarify something; When you're in N and you engage the clutch and shift into 1st, can you let off the clutch easliy, without the brakes and without your foot on the gas, and make the car move forward by itself. It seems from what you guys are saying this can be done.

I do it all the time. I leave for work very early in the morning and I have an aftermarket exhaust. I do this to keep the RPM at a minimum to not wake up the neighbors. I can work my way up to 3rd without touching the gas pedal.

 

[jasonstang]

I do it all the time. I leave for work very early in the morning and I have an aftermarket exhaust. I do this to keep the RPM at a minimum to not wake up the neighbors. I can work my way up to 3rd without touching the gas pedal.

I do that on cold engine too (I rarely warm up). No throttle just feel the clutch plus it's all downhill.

 

[15wile]

I'm driving an auto and looking to go stick within the next couple years. I wanted to clarify something; When you're in N and you engage the clutch and shift into 1st, can you let off the clutch easliy, without the brakes and without your foot on the gas, and make the car move forward by itself. It seems from what you guys are saying this can be done.

Yeah, you just gotta be very easy on the clutch when doing this. Slooooowly ease out, and you won't stall her. Dump it quick, and she stalls. It takes a little getting used to.

 

[BmacIL]

I assure you, it is possible to stall this car.

Related note: don't try to teach your wife to drive stick in a 435hp car.

I actually find this car easier to drive/launch than the last car I taught my wife to drive stick on :shrug:

 

[ghst]

I assure you, it is possible to stall this car.

Related note: don't try to teach your wife to drive stick in a 435hp car.

I taught myself in this car, and I stalled maybe twice, max. Been able to drive no problem, rev match, downshift, etc. My friends who autocross and have driven stick for years all tell me that I'm great. :shrug:

 

[Coconut]

Yes, the car will raise RPM's slightly. That combined with the low end torque will make it difficult, but not impossible to stall. I don't really find it that intrusive, it actually makes the car easier to drive. I don't even need to add gas when reversing. I find rev hang much more intrusive.

 

[BobbyGT]

Yes, all true, Norm. My point was that this isn't dumb logic. An engineer at Ford spent some time working out and tuning the when and how much for this in order to make it smooth and seamless. It is quite literally, part of what's referred to as Features Calibration. The fact that most MT cars have it doesn't excuse that fact. I have driven several cars with much less intervention off-idle and that require more throttle to get the car going. That's all in the OEM's calibration tuning.

Yeah I understood what you were saying the whole time. The others saying that "all manual cars do this" are also true, but without a doubt there is something with the tuning. I can easily let off the clutch, not apply power, and my car will begin rolling in the mustang.

In my previous GTI, I could do the same, but it was not nearly as easy, the car would buck around but eventually start moving without throttle, but it was much more difficult.

In an apples to apples comparison, testing the "no Gas" start from a complete stop, I bet my GT would start moving 10/10 times, GTI would stall 5/10 times.

 

[jasonstang]

Yeah I understood what you were saying the whole time. The others saying that "all manual cars do this" are also true, but without a doubt there is something with the tuning. I can easily let off the clutch, not apply power, and my car will begin rolling in the mustang.

In my previous GTI, I could do the same, but it was not nearly as easy, the car would buck around but eventually start moving without throttle, but it was much more difficult.

In an apples to apples comparison, testing the "no Gas" start from a complete stop, I bet my GT would start moving 10/10 times, GTI would stall 5/10 times.

Well you are comparing a 5.0L to a 2.0L engine at idle. The torque of the 5.0L will be twice as much at idle vs your GTi 2.0L with no boost probably more because of the lowered compression ration of the turbo engine. Plus there is a lot rotating mass on the 5.0L so naturally it will move easier. When I had my RX-8 which has like almost no torque, it's pretty hard to do this as the whole car would shake and engine would struggle.

 

[15wile]

I actually find this car easier to drive/launch than the last car I taught my wife to drive stick on :shrug:

I tried to teach my wife to drive stick just once. Gave up almost immediately. Sh*t was brutal, man.

Of course, you could say I wasn't terribly motivated. After all, I don't want her taking my car all the time, thus leaving me with the crapwagon (the '14 Jetta Sportwagen).

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