Car Tuning Fuel and Ignition Management 4

Question 1

What is 'knock' (detonation) in an internal combustion engine?

Accepted Answer

Uncontrolled auto-ignition of the end-gas before the flame front arrives, causing destructive pressure spikes

Answer

Detonation occurs when compressed end-gases spontaneously ignite ahead of the advancing flame front, generating sharp pressure spikes that can destroy pistons and bearings.

Question 2

A tuner wants to run more ignition advance to gain power. What is the primary limiting factor on a pump-gas street build?

Accepted Answer

Fuel octane rating — lower octane fuel detonates at less advance

Answer

Octane is the fuel's resistance to auto-ignition; lower octane limits how much advance can be used before detonation occurs and damages the engine.

Question 3

What does 'lambda' represent in engine tuning?

Accepted Answer

The ratio of actual AFR to the stoichiometric AFR for that fuel (1.0 = stoich)

Answer

Lambda normalizes AFR to any fuel type: 1.0 is always stoichiometric, below 1.0 is rich, and above 1.0 is lean regardless of whether the fuel is gasoline, E85, or methanol.

Question 4

What is the role of the crankshaft position sensor (CKP) in ignition management?

Accepted Answer

It provides the ECU with RPM and piston position data to time spark delivery precisely

Answer

The CKP sensor reads reluctor wheel teeth to give the ECU accurate RPM and crankshaft angle, which is the fundamental reference for calculating when to fire each ignition coil.

Question 5

Why might a tuner add a water-methanol injection system to a high-boost turbocharged engine?

Accepted Answer

The mixture cools the intake charge and raises effective octane, allowing more boost and timing advance

Answer

Water-methanol vaporizes in the intake, lowering charge temperature and acting as an octane booster, effectively suppressing knock and enabling more aggressive tune parameters.

Car Tuning Practice Test

Car Tuning Practice Test

Car Tuning Fuel and Ignition Management 4