MPFI Engine

It is also used for testing purposes. You would test the draw of the starter doing that exact method.

My GMC van manual says to depress the pedal slightly when very cold. This engine ALWAYS floods out if you touch the pedal at all.

Motor manufacturers go to extremes to ensure that ECM calibrations provide a 'no touch' start - no touch on the throttle.

Sensors used on the engine tell the ECM the temperature of the engine and often the ambient temperature so that the correct start and idle fuelling conditions are set when you turn the key.

Why would you need to depress the throttle? If your engine has truly 'flooded' after shut-down then the cause should be rectified (eg: leaky injectors)

Only a vehicle with a carburetor would require you to press the pedal slightly and in that instance it is setting the choke releasing the cam under cold conditions if the vehicle had been driven and reached normal operating temp. the choke would remain open until the pedal was pressed. If it floods easily it is probably the choke setting or the choke pull off is damaged or needs to be set. The fuel injection vehicle is different as stated above the pedal would send a flood condition signal to the computer if pressed to the floor. The pedal only controls air flow so unlike a carburetor engine the fuel injection does not spray any fuel into the engine when the pedal is pressed. The TPS sends a signal telling the computer how open the butterfly valve is and the computer responds with the proper air fuel mixture. If the vehicle is warm and running in the closed loop mode. If it is cold and running in the open loop mode it runs off of preset parameters set in the computer.By pressing the pedal to the floor the computer goes in to flood mode and only cycles on the injectors at varied intervals to over come the flood condition. Best to let the system do its job. If a fuel injection engine requires pressing the accelerator to start you have problems.

Engines fitted with carburetors are supposed to be started without the pedal pressed too. The instructions are in the owner's manual or on the visor. The main difference is that you had to depress the pedal once to put in some extra fuel and to set the linkages to their proper start position. Some models had more specific instructions. Because of the way carburetors work, starting with the pedal at the floor would lean the mixture to clear a flood.

A new or well adjusted carburetor engine would start this way. Once the engine gets old and too many mechanics have adjusted what they don't know how, every engine ends up with its own special starting method learned through trial and error.

Fuel injected systems could have been programmed to start in many ways. The method that new car buyers already knew for carburetors was perfectly acceptable. No retraining was necessary and consumer confidence is enhanced since the new technology doesn't seem much different than the old reliable technology. Pressing the pedal was fine though it does nothing. Leaving the pedal up is a signal to the ECM for it to start normally. Starting with the pedal at the floor is a signal that the ECM should lean the mixture to clear a flood, just like a carburetor.

The ECM with its sensors and actuators control everything needed to start without driver input. Model specific sequences are eliminated and engines from every manufacturer start the same way at any temperature or age. Customers accept the new technology because it is clearly superior in every way to the old reliable carburetor.