© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Chapter 9 Automotive Engine Designs and Diagnosis

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Introduction to Engines All gas and diesel engines are internal combustion engines Largest part is the cylinder block The cylinder head sits on top of the block Engines are constructed from iron, aluminum, magnesium, and plastics

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Engine Classifications Operational cycles Number of cylinders Cylinder arrangement Ignition type Cooling system Fuel type Valve train type – OHV, OHC, DOHC

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Overhead Valve

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. OHC ValvetrainDOHC Valvetrain Overhead Cam

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Intake Stroke – The piston moves down and the intake valve opens to draw air and fuel into the cylinder Compression Stroke – The piston moves up with both valves closed to compress the mixture Four-Stroke Cycles

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Power Stroke – With both valves still closed, the mixture is ignited, and the expansion pushes the piston back down Exhaust Stroke – The piston moves up and pushes the spent gasses out the open exhaust valve Four-Stroke Cycles (Cont.)

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Firing Order The sequence in which the cylinders are ignited Also indicates position of the pistons when a cylinder is firing For a four-cylinder firing order of 1342 – #1 is at TDC compression – #3 is at BDC intake – #4 is at TDC exhaust – #2 is at BDC power

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Firing Order Examples

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Knowledge Check Explain what takes place during the four strokes of a gasoline engine.

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Two-Stroke Gasoline Engines Produce power every two strokes instead of every four Not as fuel efficient as four-cycle Emits more pollution than a four-cycle Oil for lubrication is mixed with the fuel

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Engine Rotation Rotation standard set by SAE Most engines rotate counterclockwise as seen from the rear or flywheel side

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Many factors affect combustion Incomplete combustion causes the engine to run poorly Starts at the spark plug gap Should move steadily across the air/fuel mixture The rapidly expanding gases force the piston down Combustion

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Engine Configurations Inline V-type Slant Boxer or opposed

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Engine Measurement and Performance Bore and stroke Displacement Compression ratio Engine efficiency Torque vs. Horsepower

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Bore and Stroke

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Displacement

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Compression Ratio

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Knowledge Check How does compression ratio affect an engine’s performance?

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Engine Volumetric Efficiency

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Engine Thermal Efficiency

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Engine Mechanical Efficiency

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Torque vs. Horsepower

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Hybrid Vehicle Engines Many hybrid electric vehicles (HEVs) use specially modified gasoline engines for improved fuel economy – Atkinson cycle engines – Miller cycle engine

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Atkinson Cycle Holds the intake valve open longer - during the time compression is taking place The open intake valve allows some of the mixture to escape back into the intake manifold This reduces the effective displacement and compression ratio

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Atkinson Cycle (Cont.)

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Miller Cycle An Atkinson cycle engine with forced induction (supercharger) The decrease in intake air and lower power is compensated for by the supercharger

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Diesel Engines Main power source for heavy-duty applications Operates similar to a gasoline engine Use high compression pressure to ignite fuel Larger than comparable gas engine Produce large amount of torque Run at low speeds

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. HCCI Engines Homogeneous charge compression ignition (HCCI) engines have the torque and efficiency of a diesel and the low emissions and power of a gas engine

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Other Powerplants Hybrid vehicles have at least two types of power or propulsion systems – usually an ICE and electric motors Hybrids do not require plugging in to charge EVs do require plugging in

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Toyota Prius MG2

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Other Powerplants (Cont.) Battery operated electric vehicles (EVs) – operate solely on battery powered electric motors

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Other Powerplants (Cont.) Fuel cell electric vehicles – use hydrogen to generate electricity to power electric motors

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Other Powerplants (Cont.) Rotary engines – another type of four- cycle ICE Rotary engines use a rotating triangular rotor, no reciprocating engine parts

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Other Powerplants (Cont.) Variable compression ratio engines can maximize power when needed and minimize fuel consumption when power is not needed

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Knowledge Check How do hybrid vehicle powertrains differ from non-hybrid vehicles?

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Engine Identification

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Engine Identification (Cont.)

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Compression Test – Checks the compression of each cylinder Cylinder Leakage Test – Helps determine where compression is leaking Power Balance Test – Checks to see if all cylinders are producing the same power Vacuum Test – Helps to determine the engine’s efficiency by measuring manifold vacuum Engine Diagnostics

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Compression Testing Relative compression – Measures starter current flow when cranking Cranking compression – Dry and wet tests – Wet test checks for rings sealing Running compression – Used to determine valvetrain problems

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Relative Compression Test

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Cranking Compression Test

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Running Compression - Good

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Running Compression - Bad

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Knowledge Check A four-cylinder engine has the following compression readings, what could be the cause? 1) 150 psi 2) 150 psi 3) 80 psi 4) 80 psi

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Cylinder Leakage Test Pressurizes the cylinder Used to determine cause of leakage – Cracked head or leaking head gasket – Leaking rings – Burnt valves

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Power Balance Testing Checks for each cylinder’s contribution Can be done manually Typically a scan tool test

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Knowledge Check While discussing power balance testing, Technician A says each cylinder should drop the same rpm. Technician B says a cylinder that does not drop rpm is a good cylinder. Who is correct?

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Engine Diagnostics (Cont.) Engine Oil Pressure Testing – Determines the wear on internal engine parts Fluid Leaks – Be sure to identify the correct fluid that is leaking Exhaust Smoke – Exhaust smoke diagnosis chart

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Engine Diagnostics (Cont.) Exhaust Smoke – Gasoline Engines – Grey/black smoke indicates excessive fuel – Blue smoke indicates burning oil – White smoke is coolant or ATF in combustion

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Common Engine Noises Abnormal Combustion Noises – Detonation or ping is most noticeable during acceleration Usually caused by advanced timing, overheating, or lean mixtures – Preignition or spark knock occurs when ignition occurs before the spark plug fires Caused by carbon deposits, incorrect spark plug, and cross firing

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Cleaning Carbon Deposits Excessive carbon buildup in the combustion chamber can cause several problems Chemical additives may remove or reduce deposits Carbon blasters force crushed walnut shells into combustion chamber to break up deposits

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Ring Noise – A high-pitched rattling during acceleration Piston Slap – Normally heard when the engine is cold Piston Pin Knock – A sharp, metallic rap Ridge Noise – High-pitched rapping, louder on deceleration Common Engine Noises (Cont.)

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Rod-Bearing Noise – Usually heard at idle Main Bearing Noise – A dull, steady knock Tappet Noise – A light, regular, clicking sound Ping or Detonation – Rattling noise during acceleration Common Engine Noises (Cont.)