Car Tuning Chiptuning 5

Question 1

What is the significance of 'injector dead time' (or offset) in a fuel map?

Accepted Answer

Time the injector takes to physically open fully before fuel flows — must be compensated for accurate fueling

Answer

Injector dead time is the brief delay between when the ECU commands an injector open and when it actually flows fuel; compensating for it ensures accurate fuel delivery especially at low pulse widths.

Question 2

What problem can result from using pump gasoline (87 octane) in a chiptuned car calibrated for 93 octane?

Accepted Answer

The ECU will pull timing via knock retard, reducing power and potentially causing sustained detonation

Answer

Lower-octane fuel is more prone to detonation; the knock sensor detects it and the ECU pulls timing, losing the power gains of the tune and risking engine damage.

Question 3

What does 'rev limiter' tuning typically involve in chiptuning?

Accepted Answer

Raising or adjusting the RPM at which the ECU cuts fuel or spark to protect the engine

Answer

Rev limiter tuning adjusts the RPM threshold where the ECU enforces a fuel cut or ignition cut, often raised to match strengthened engine internals.

Question 4

In diesel chiptuning, what is the primary variable tuners modify to increase power?

Accepted Answer

Fuel injection quantity and injection timing (rail pressure and duration)

Answer

Diesel engines have no spark; power is increased by injecting more fuel for longer durations and optimizing injection timing relative to piston position.

Question 5

What is 'lambda 1.0' and why is it the reference point in tuning?

Accepted Answer

The stoichiometric air-fuel ratio where all fuel and air are completely consumed in combustion

Answer

Lambda 1.0 represents the stoichiometric ratio (~14.7:1 for gasoline) where combustion is chemically complete; tuners use it as a reference when targeting richer or leaner mixtures.

Car Tuning Practice Test

Car Tuning Practice Test

Car Tuning Chiptuning 5