TR Forums

Captain Ned wrote:

Pancake wrote:

Chrispy_ wrote:

Interesting comments from Synthetel2 about gas pedals being closer to binary than linear; I don't think I've ever owned a car with an electronic throttle, so that kind of figures - where just 10% throttle = 90% peak torque at that engine speed.

Interesting comment but complete crap. The throttle exists to make fuel-to-air ratio combustible in petrol engines, which is in a fairly narrow range compared to diesels. My car has an electronic throttle and I know it quite well as I pull it apart and service it with love and care and sweet tenderness... Anyway, throttles are most definitely not "binary" in how they work. The clever little computer in my car modulates the throttle (in conjunction with mass air flow sensor) to give the perfect blend of air and fuel to keep each cylinder (multipoint EFI) burning happily at the required torque output at current RPM as demanded by my right foot. It's a beautiful thing.

Partially correct (the complete crap comment is incorrect). Modern TBW systems not only manage fuel-air ratios but also manage torque output by proportioning physical throttle-plate movement to actual gas pedal movement, and this management occurs to ensure that the engine never sends torque to the transmission that would exceed the transmission's torque rating.

synthtel2 wrote:

Some TBWs get it down to where it doesn't feel obviously wrong, but IME it's still around the bad end of mechanical throttles (with oversized intake manifolds, that kind of thing). At the good end of TBWs, I can see it being personal preference though; between a non-eccentric mechanical throttle, small intake manifold, and substantial air reservoir just upstream of the throttle body, my car's accelerator probably has a lot more bite than the average driver would consider comfortable.

Chrysler/Dodge/Jeep just doesn't know how to build electronics that don't suck, AFAICT. Their performance vehicles (not a Demon or anything, but definitely 300C and I think some SRT stuff) are still blatantly laggy, and I'd agree with Ned on Jeep's goals if not for how even on a Wrangler it's [push accelerator 10% -> nothing happens -> wait a few hundred millis -> BOOM hope you weren't trying to do a smooth takeoff on ice sucka!]. If it's borderline impossible to finely modulate power delivery on a freaking Jeep Wrangler, someone has dun goofed.

ludi wrote:

Waco wrote:

I still prefer throttle cables to electronic throttles. One more thing to break, one more thing to introduce lag, etc. I don't mind the system on my C5, but I really wish it were simpler.

Eh. Can make that argument against any electronic upgrade that automotive engines have seen over the past 60-odd years, but efficiency and reliability keep improving. The next step is a GDI engine with no throttle plate at all.

Pancake wrote:

Captain Ned wrote:

Pancake wrote:

Interesting comment but complete crap. The throttle exists to make fuel-to-air ratio combustible in petrol engines, which is in a fairly narrow range compared to diesels. My car has an electronic throttle and I know it quite well as I pull it apart and service it with love and care and sweet tenderness... Anyway, throttles are most definitely not "binary" in how they work. The clever little computer in my car modulates the throttle (in conjunction with mass air flow sensor) to give the perfect blend of air and fuel to keep each cylinder (multipoint EFI) burning happily at the required torque output at current RPM as demanded by my right foot. It's a beautiful thing.

Partially correct (the complete crap comment is incorrect). Modern TBW systems not only manage fuel-air ratios but also manage torque output by proportioning physical throttle-plate movement to actual gas pedal movement, and this management occurs to ensure that the engine never sends torque to the transmission that would exceed the transmission's torque rating.

In other words, it reduces torque by reducing fuel and air which is burnt to generate said torque... So, what are you describing is an effect of having a computer management the power output of the engine. However, the actual physical purpose and function of the throttle is still simply this - to ensure fuel-to-air ratio is combustible in a petrol engine. i.e. I am COMPLETELY correct.

Pancake wrote:

I don't think you're EVER going to have a modern car that behaves with the "brap! brap!" feel of an old-style carburettor engine at neutral. Because of emissions control regulations. But the modern cars have way more power, are more efficient and cleaner.

Chrispy_ wrote:

Fuel economy is therefore a purchasing decision, not a driving style. Lets face it, if you were concerned about gas mileage you'd have bought a 63mpg Prius.