What happen internally when you step on the gas? (power/electricity wise)

[BratPAQ]

I'd just like to understand what happen on the car, electricity wise or power wise when you step on the gas? This is for AT car, does the power source switch from something to something else?

Our car is having a problem with idle mode, a honda mechanic suggested ILP (idle learning process) and it didnt work, i noticed that the problem isnt necessarily on the idle part, sometimes if I "flick" on the gas and quickly release it, it feels like its disconnecting from one power and connecting to another, but since i quickly release it the connecting part didnt happen and the engine would stop. Engine also stop when shifting from D to N or P (but not always). The problems seems to persist on switching to and from idle.

Also we brought it to honda and there was a note on the last PM "check alternator charging", so i thought its a problem with alternator, but i tested the alternator with this and it passed:

Clues That Your Alternator is Bad
There are two tests you can perform at home that can give you an indication whether your alternator is working properly. Try one or both of these before spending any money on repairs:

Try the headlight test. Turn your car headlights on while the car is running. Do this outside so carbon monoxide gas buildup doesn't become a problem. Press the accelerator while the car is in park. If the headlights dim or get brighter when you press the accelerator, your alternator could be bad. If the headlights remain the same, your alternator is probably fine.
Try the battery test. Turn the car ignition on and open the engine hood. While the car is running, remove the negative cable on the battery. If the car suddenly stalls and dies, your alternator could be bad. This is because the alternator is not generating enough electricity to keep the car running. If the car keeps running, the battery might be the problem.

the car will be brought back to honda tomorrow, but i just like to know or learn whats this problem.

[niky]

Depends on how old your car is.

When you press on the gas pedal, a throttle plate (literally a circular plate that rotates to either close off or open the intake) moves. but there are two ways it can move, via cable or via electric motor.

If it's a cable-throttle car, when you close the throttle, the idle-air control valve opens up to let air bypass the closed throttle.

If it's an electronic throttle actuated by an electric servomotor, it can either use the idle air control valve or the computer will keep the throttle partially open when you let your foot off so the engine doesn't die.

From what the technician says, I'm wagering your car is a newer Honda, equipped with an ECT. What's happening is the computer is not adjusting the throttle opening when you shift, so the sudden shock in change of load kills the engine.

[jick.cejoco]

Try the battery test. Turn the car ignition on and open the engine hood. While the car is running, remove the negative cable on the battery. If the car suddenly stalls and dies, your alternator could be bad. This is because the alternator is not generating enough electricity to keep the car running. If the car keeps running, the battery might be the problem.


NEVER, NEVER, NEVER disconnect the battery with the ignition switch on or the engine running. the unregulated voltage spike can ruin your sensitive electronic equipment including the PCM. use a voltmeter to check the voltage both engine off and engine running and with all electrical loads on. you may also check the current output by using a clamp on inductive ammeter to the alternator output wire.

[t2erns]

what model and year? since you're bringing it back to casa i think it's best to request a full diagnostic scan (if it's etcs i hope they wont get a P1659 dtc which is very common to honda). might be also a transmission issue.

[BratPAQ]

its honda city 2009 1.5e, tried that disconnecting battery to test the alternator, ok naman, nga pala may kasamang "nginig" yung kotse for 2 to 3 seconds na wala naman noon, yung parang nginig ng sasakyan pag pinatay mo ignition, thats my cue that the engine might die during traffic or slow down.

anyway, nasa casa na yung sasakyan, meron daw hose na may butas, di lang naitanong ng wife ko kung anong hose, at malamang daw sa computer ang sira kaya aayusin lang yung computer.

[BratPAQ]

just got the car back, ok na, they replaced the hose and did something to the computer, 1st thing i noticed is the rpm on idle, its not up to 750 to 800, previously with the engine problem its usually at 550 to 600.