Car Tuning Chiptuning 3 — Questions and Answers
Question 1: What is the function of an 'intercooler' in a turbocharged chiptuned engine?
- Cool engine oil after hard use
- Cool compressed charge air to increase its density before entering the engine (Correct answer)
- Cool the turbocharger bearing housing
- Regulate coolant temperature
Correct answer: Cool compressed charge air to increase its density before entering the engine
An intercooler reduces the temperature of compressed air from the turbo, increasing air density and allowing more fuel to be added safely for higher power output.
Question 2: In ECU terminology, what is a 'base map' or 'base tune'?
- The factory OEM calibration
- A starting-point calibration used before dyno refinement (Correct answer)
- A tune that only adjusts idle parameters
- The minimum safe fuel map
Correct answer: A starting-point calibration used before dyno refinement
A base map is a preliminary calibration — often derived from a similar car's tune — used as a safe starting point before live dyno or data-logging refinement.
Question 3: What does increasing the 'global fuel trim' (or 'global enrichment') do in a tune?
- Advances ignition timing across all cells
- Adds or subtracts a percentage of fuel across the entire fuel map simultaneously (Correct answer)
- Increases boost target globally
- Reduces idle speed
Correct answer: Adds or subtracts a percentage of fuel across the entire fuel map simultaneously
A global fuel trim applies a percentage correction to all fuel map cells at once, useful for quick rich/lean adjustments without editing individual cells.
Question 4: Which chiptuning method involves splicing a piggyback device into the injector signal wires?
- Full ECU remap
- OBD-II flash tune
- Inline signal interceptor / piggyback tuning (Correct answer)
- Standalone ECU replacement
Correct answer: Inline signal interceptor / piggyback tuning
Piggyback units intercept and modify sensor or injector signals between the factory ECU and engine components without reprogramming the OEM ECU.
Question 5: What is 'volumetric efficiency' (VE) and why does it matter in tuning?
- The ratio of fuel injected to air consumed
- How effectively an engine fills its cylinders with air relative to theoretical maximum (Correct answer)
- The efficiency of the turbocharger compressor
- The ratio of brake power to indicated power
Correct answer: How effectively an engine fills its cylinders with air relative to theoretical maximum
VE measures how well the engine breathes; tuners use VE tables to accurately calculate how much fuel to inject based on actual cylinder fill.
Question 6: What risk does running excessively lean AFR pose to a turbocharged engine?
- Fouled spark plugs
- Elevated EGT and potential piston or valve damage (Correct answer)
- Increased turbo lag
- Excessive carbon buildup on intake valves
Correct answer: Elevated EGT and potential piston or valve damage
Lean mixtures burn hotter, raising exhaust gas temperatures (EGT) to levels that can melt pistons, burn valves, or damage the turbocharger.
Question 7: What is the role of the 'MAF sensor' in a speed-density converted tune?
- It remains the primary load input
- It is disabled or deleted; MAP and IAT sensors replace it for load calculation (Correct answer)
- It controls turbo wastegate duty cycle
- It measures exhaust backpressure
Correct answer: It is disabled or deleted; MAP and IAT sensors replace it for load calculation
Speed-density tuning uses manifold pressure (MAP) and temperature (IAT) to calculate engine load, eliminating MAF sensor limitations especially useful with large intake mods.
Car Tuning Chiptuning 3
What is the function of an 'intercooler' in a turbocharged chiptuned engine?