The throttle mapping is nonlinear so that something like 10% pedal gives you 50% gas, so it's really hard to control smoothly.
The 1st gear to 2nd gear shift also has really bad rev hang where you have to wait for a very long time in between 1st and 2nd gear before you can engage the next gear. This makes controlling the car at slow speeds to be really jumpy and uncomfortable. Lots of manual transmission cars made after 2010 have rev hang supposedly for emissions purposes.
One way of solving this is to buy a $700 Cobb Accessport and flash your car's ECU with a "stage 1" off-the-shelf Cobb tune. This makes the throttle mapping linear and removes most of the rev hang. These off-the-shelf maps are supposedly CARB compliant.
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Cobb also has a stage 2 tune that requires replacing the turbo-back exhaust of the car (a.k.a. a downpipe/j-pipe), which is less restrictive for emissions and adds a good amount of horsepower. Supposedly these stage 2 tunes and turbo-back hardware are CARB compliant nowadays, but the laws are fairly new so Cobb sold non-compliant versions up to a few years ago iirc. Tuner shops can also create their own non-compliant custom tunes using the Accessport.
It's a similar world with fuel injected dirt bikes. Although the throttle is mechanical, some specific fuel and ignition mapping choices the manufacturers provide results in huge amounts of acceleration with small amounts of throttle input. The exact reasons why aren't published, but the general consensus is it relates to emissions.
Remapping the factory ECU completely resolves the issue, albeit obviously a "defeat device" per the EPA
"Lots of manual transmission cars made after 2010 have rev hang"
I think this is similar to "skip shift". The idea is to force you to shift from 1st to 4th so you use the more efficient ratio. Stupid idea in my experience since it forced higher RPMs in an inefficient gear and can have some drivability issues in traffic and on hills. You technically don't need a tune to eliminate this. They make jumpers that sit between your computer cable and the transmission that eliminate the gear lockouts. You could also pullout in second and it would bypass the skipshift logic since you aren't in first.
The rev hang or skip shift isn't about unburnt hydrocarbons, it's about efficiency standards. It's a different problem - emissions efficiency is one thing and emission compound/type restrictions are another.
Incorrect. The engine speed hold is there to optimize mixture while the engine decelerates, instead of just slamming the throttle shut. Depending on where the fuel is injected, cutting off fuel and air instantly leads to either too much fuel or too much air in the cylinders. The electronic rev hang corrects this to reduce NOx and unburnt fuel. It does not improve fuel efficiency.
The difference between DI and port injection is only which thing is escaping the catalytic converter. With port injection the engine is rich after lifting off the throttle, and hydrocarbons escape. With direct injection the engine leans out, and NOx escapes. In both cases the rev hang exists to keep the emissions system in its effective air/fuel ratio range. Every hanging MT car I ever owned was DI.
That's very odd. DI should only be firing a full shot injector as the air is coming in, or already came in. It really shouldn't lean out. If your DI car had rev hang, it's for other reasons.
We were discussing the 2015 WRX after all, it is port injected. The guy who wants to delete the rev hang from his VA WRX is advocating to blowing unburnt gas right out of the tailpipe, like a psycho.
The throttle mapping is nonlinear so that something like 10% pedal gives you 50% gas, so it's really hard to control smoothly.
The 1st gear to 2nd gear shift also has really bad rev hang where you have to wait for a very long time in between 1st and 2nd gear before you can engage the next gear. This makes controlling the car at slow speeds to be really jumpy and uncomfortable. Lots of manual transmission cars made after 2010 have rev hang supposedly for emissions purposes.
One way of solving this is to buy a $700 Cobb Accessport and flash your car's ECU with a "stage 1" off-the-shelf Cobb tune. This makes the throttle mapping linear and removes most of the rev hang. These off-the-shelf maps are supposedly CARB compliant.
---
Cobb also has a stage 2 tune that requires replacing the turbo-back exhaust of the car (a.k.a. a downpipe/j-pipe), which is less restrictive for emissions and adds a good amount of horsepower. Supposedly these stage 2 tunes and turbo-back hardware are CARB compliant nowadays, but the laws are fairly new so Cobb sold non-compliant versions up to a few years ago iirc. Tuner shops can also create their own non-compliant custom tunes using the Accessport.