Idiot guide to accelerating

[Rocho]

Ok, This will sound very basic to some but I\'m sure its quite easy to answer...

When you push the accelerator does this make the injectors pump more petrol in and the engine mixes the air with it, or does the accelerator open the air intake more and the engine then pumps more petrol in to make the fuel?

[RemarkLima]

Depends if it\'s injection or carb\'d

Modern fuel injected cars have a load of parameters in the ECU, so you press the throttle and it open the plates so there\'s more air being sucked into the engine.

There is a Throttle Position Sensor which gets updated with the new throttle position.

Then there\'s air temp, and if turbocharged, air pressure (both in the manifold, the last bit before the engine).

With all this info the computer then knows to add the "mapped" amount of petrol into the air for the best combustion.

Carbs work on a vaccuum (sp?), and basically suck in the right amount of fuel for the amount of vaccuum the engine is creating (plus extra for sudden changes in throttle etc...).

Very modern cars, inc the RX8 are throttle by wire so the pedal is only connected to a sensor and the amount it\'s opened by is all computer controlled. Clever stuff!

HTH a bit

[m4drx]

simultaneously, the engine is not a carberettuer engine so has an ECU to control fuel injestion and AF ratios etc ie a MAP. when you press the throttle it is attached to a cable which opens the butterflys in the throttle body however as they open a device called the TPS throttle position sensor which tell the ecu how hard you are pressing the map sensor measure the volume of air/boost, the temp sendor ensures the ratio is correct and fuel is added as necessary via the ecu tlling pump and injectors and away you go.

very simplified but essentialy what happens the modern (or in our case premature) car is very advanced.

hth

[m4drx]

snap .................

[RemarkLima]

Make a wish

[Rocho]

Cheers guys, I\'m now enlightened!