auto tech ch 3 study
Misfire Code and Misfire Conditions
A misfire code pinpoints the cause of a misfire condition.
A misfiring cylinder occurs when an engine combustion chamber is not igniting and burning its air-fuel mixture on that cylinder’s power stroke.
Ignition System Diagnosis
Burned secondary connections inside direct and indirect ignition coils indicate high-voltage leakage.
The ignition primary voltage test checks the voltage fed to the ignition coil.
Spark Plug Issues
Bad spark plugs can cause hard starting, misfiring, poor fuel economy, lack of engine power, and exhaust odor.
An oil-fouled spark plug is characterized as shiny and dark gray or black.
A wire feeler gauge should be used to measure spark plug gap.
All the secondary wires should be removed from an engine before new ones are installed (True).
A faulty ignition coil pack winding will normally measure high or infinite resistance on an ohmmeter (True).
When a knock sensor (KS) detects pinging or knocking, it signals the powertrain control module (PCM) to retard ignition timing or increase turbo boost (True).
Cooling System Diagnosis
Initial Assessment
The first step toward diagnosing cooling system problems is to gather information about the symptoms from the vehicle owner or service writer.
Engine Coolant Concerns
Air bubbles in the engine coolant may indicate that engine combustion gases are entering the cooling system.
Safety Precautions
It is important to never remove the pressure cap from the cooling system if the coolant is at operating temperature, as this can release pressure and cause coolant to boil.
Leak Detection
A cooling system pressure test is used to identify the source of cooling system leaks.
Thermostat and Cooling System Components
Vehicle manufacturers do not install thermostats that are interchangeable across all cooling systems in the manufacturer’s models for a selected year (False).
Engine heat causes the hardening of cooling system hoses after an extended service life.
Technicians often perform on-vehicle radiator repairs more frequently than replacing a damaged radiator due to the construction of late-model vehicle radiators (True).
Supercharger cooling systems typically operate at higher pressures and temperatures than standard engine cooling systems (True).
Conditions for Flushing
Technicians should flush the cooling system with a cleaning chemical if rust and scale are found in the system.
Appearance of Contaminated Coolant
When water, antifreeze, and engine oil mix, it turns milky white, indicating a problem in the cooling system.
Water Pump Failures
Symptoms of a faulty water pump can include leaking coolant, failing to circulate coolant, and producing grinding or chattering noises.
Thermostat Discussion
A stuck thermostat can cause engine overheating or overcooling (True).
If the thermostat outlet hose stays cool while the engine reaches operating temperature, the thermostat is likely not opening and is defective (True).
Engine Cooling Fan Issues
A faulty engine cooling fan may cause various engine issues except for revving and idle problems.
Minimum coolant strength should protect at a temperature several degrees lower than the lowest normal temperature for the area's climate (True).
Coolant voltage levels must reach between 1-2 volts DC before problems arise in the system (False).
Exhaust System Characteristics
The vehicle's exhaust system design does not affect the suspension spring rate.
A dual exhaust system is typically not installed on small, high-fuel-economy engines (False).
Exhaust system service is often necessary when a component in the system rusts and begins to leak (True).
Exhaust System Repair Guidelines
During exhaust system repairs, technicians should:
Check the exhaust system pipe routing for adequate clearance between the system and the vehicle's body and chassis.
Reinstall all heat shields in the correct locations.
Use exhaust hanger pliers to remove and install rubber isolators on exhaust hangers.
Avoid tightening exhaust system clamps until they visibly indent exhaust pipes to eliminate vibration (False).
Pipe Expander Use
A pipe expander should be used to enlarge pipe ends as needed during exhaust system repairs.
Stainless Steel Exhaust Systems
Only special, heavy-duty clamps designed for stainless steel systems should be used for attaching exhaust components (True).
Sound and Emission Reduction
The exhaust system muffles sound emissions and treats engine exhaust gases effectively (True).
Catalytic Converter Temperature Check
A good catalytic converter should not have a temperature difference greater than 10°F front to rear (False).
Catalytic converter temperature readings should be uniform front to back (True).
Back Pressure Analysis
High back pressure indicates a restriction in the exhaust system (True).
A well-designed exhaust system should exhibit low back pressure (True).
Exhaust System Fastener Treatment
Using a 6-point socket is advisable for loosening and removing exhaust system fasteners to prevent stripping (True).
Applying penetrating oil or heat on rusted or corroded fasteners is also recommended (True).
Suspension System Concerns
Common symptoms of suspension system problems include abnormal noises, steering wheel pull, and front end shimmy.
Weak braking is not a common symptom.
Shock Absorber Tests
A shock absorber bounce test and visual inspection are essential for locating problems (True).
Spring fatigue causes lowered vehicle ride height (True).
Curb weight is defined as the weight of a vehicle occupied by a driver and one passenger (False).
Removal Tools
A fork tool or ball joint separator is necessary to force the ball joint stud from the steering knuckle during coil spring removal.
All force should be released from the leaf spring before driving out the eyebolts or shackle bolts during leaf spring replacement.
Bushing Driver Tools
A bushing driver tool is one method to press a rubber bushing into and out of a suspension control arm (True).
Strut Assembly Procedures
The nut on the end of the strut shock rod should be removed when the strut assembly is taken out from a vehicle (True).
Post-Suspension Work
A four-wheel wheel alignment and ADAS calibration must be performed before releasing the vehicle back to the owner (True).
Troubleshooting Electronically Controlled Suspensions
Trial-and-error parts replacement should be avoided when an electronically controlled suspension system displays a trouble code.
Shock Absorber Test Results
If a vehicle's body bounces five times after a shock absorber bounce test, it indicates faulty shock absorbers (True).
Air Shock Repairs
If one air shock on a vehicle is leaking, it does not necessarily mean all air shocks or springs must be replaced; shock air lines can often be repaired (True).
Ball Joint Installation Methods
Snap rings are not a method of installing ball joints with vehicle suspension components.
Dry Park Test
A dry park test is performed to check for looseness in the steering system (True).
Steering System Noise Causes
Steering system noise can be caused by unlubricated ball sockets, low power steering fluid, and loose or slipping belts. A broken condenser is not a cause.
Fluid Level Check
The engine should be off to check the power steering system fluid level (True).
Steering Linkage Components Wear
Signs of wear in steering linkage include worn tie rods, loosening ball sockets, and excessive play in the idler arm.
Rack-and-Pinion Systems
A rack-and-pinion system has fewer parts to fail compared to a linkage-type system (True).
Power Steering Leak Checks
Checking for power steering leaks involves turning the steering wheel to pressurize all parts of the system (True).
Power Steering System Bleeding
It's necessary to bleed the power steering system after servicing any hydraulic steering components (True).
Steering Wheel Play Diagnoses
To diagnose excessive steering wheel play, checks should include worn tie rods and the condition of the system's idler arm (True).
Hard Steering Problem Diagnosis
Checking the steering gearbox and inspecting the suspension system are both essential when diagnosing hard steering problems (True).
Noise from Power Steering Pump
Checking the power steering pump’s fluid level is essential if noise originates from the power steering pump (True).
Checking Fluid Levels
The steering system’s fluid level is checked with the engine off (True).
Power Steering Belt Condition
A loose power steering belt may be worn or stretched and may require replacement (True).
The tensioner may be broken and unable to apply sufficient tension to the belt (True).
Worn Idler Arm Diagnosis
A worn idler arm is often a cause of play in a linkage steering system and must be replaced (True).