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Accelerator Control System

“Accelerator Control System (ACS) safety standard” in almost all around the world says that “The throttle shall return to the low idle position from any accelerator position or any speed which the engine is capable of”. It also dictates that “The return to low idle position shall occur within the time limit specified measured either from the time of severance or disconnection or from the first removal of the opposing actuating force by the driver”. This limit is maximum 3 second for all type of vehicle. The low idle is defined as “Low idle position’ means the position of the throttle at which it first comes in contact with an engine idle speed control appropriate for existing conditions according to the manufacturer’s recommendation. These conditions include, but are not limited to, engine speed adjustments for cold engine, air conditioning and emission control and the use of throttle setting device.”

When I start my Hyundai Verna diesel car (1.6 manual) it idles at around 800 rpm as shown in techometer. When i change the gears without even touching the accelerator, the car accelerates to different speeds in different gears and in the process the rpm also increases to above 1000rpm in 6th gear and a speed of around 60kmph (without even touching accelerator pedal). On the contrary, when I release the accelerator pedal at say around 65 kmph in 6th gear, it doesnt slows down and maintain speed of 60kpmh at above 1000rpm. (I do this with two persons sitting (around 60kg each) and AC off (so that dynamic load change does not occur) and windows closed (so air pressure inside car does not change the load)).

My question is whether my car conforming to this ACS as my car is not slowing down on releasing the accelerating pedal while other cars in market do slows down. I talked to company many times and they are not giving anything in writing just saying that all Hyundai diesel cars behave similarly. Also I would like to know that whether low idle position should change merely because of changing of gear? or it is because of some electronic control in violation of the ACS safety standards
Also what does it mean when it says that " low idle position means the position of the throttle at which it first comes in contact with an engine idle speed control"? Does it mean when we start the vehicle in neutral or in first gear? does it also means that at in any gear when accelerator is released the engine idle should return to the original value that we observed at start (provided load does not change e.g. by AC, Temp etc)
Do any one have any link that talk in detail about "throttle low ldle position as well as legal positions of the ACS safety standards

Why would you want the engine to return to idle between gears? That would create a much less smooth transition. Engine control systems are designed to maintain an above idle speed between shifts to make the transition easier as well as raising the idle under some idle conditions such as turning on the A/C.

If the engine returns to idle when you stop, and if I understand your post correctly (which I’m not sure I do), than the engine is operating normally. I have to emphasize that I’m not sure I understand your post correctly. Have you tried another of the same vehicle to see how that one reacts? That might help give you an idea whether yours is really misbehaving.

By the way, I have no idea where you’ve gotten that standard, but I’ve never heard of it here in the U.S. Automotive standards vary throughout the world, which is a major problem for auto manufacturers. Different countries have different standards. I’d bet that much of the world has no automotive safety standards at all. I truly would be interested in knowing where that standard you quoted came from.

When I start my Hyundai Verna diesel car (1.6 manual)

Obviously not from the US. Personally I think you are really over thinking this whole thing. And if you are concerned your car does not meet some spec. or another it may be best to take the issue directly to the appropriate regulatory authority.

I think he’s saying his car will cruise along indefinitely at 60kph (37mph) with his foot off the gas.

37 mph with foot of the gas? That doesn’t seem right. My automatic-equipped Ford truck, if I take my foot off the gas, it will slow down straight away to less than 15 mph. Of course my Ford truck is 40 year old technology, so maybe that’s not a good comparison; but it still doesn’t seem right the OP’s car goes 37 mph with foot off the gas. It could indeed be the idle control servo, but it could also be some issue associated with the automatic transmission.

OP, have you checked with the dealership to make sure all of the TSB’s associated have been inspected and dealt with? At the minimum, ask them for a list of all the known TSB’s and customer interest issues for the vehicle.

George, remember OP has a manual transmission. Engine idles at 800 rpm, and in 6th gear he “idles” along at 1000 rpm and 37 mph. OP, when you’re idling along at 37 mph and push the clutch in, what does engine rpm do? I’m guessing it idles down to 800 rpm. I see no problem with the operation of this vehicle.

Also, OP has diesel engine which will have more low-end torque than a gas engine and won’t stall out while in gear at idle.

Really? It’s normal that a diesel engine/manual transmission will run in the top gear at close to 40 mph with the foot off the gas? Interesting. Thanks for the explanation.

I doubt it’s normal, but then again I’ve never driven a Hyundai Verna. Maybe the owner can find another Hyundai Verna owner and ask him/her if it does the same thing.