ENGINE TUNE UP COMPREHENSIVE TEST 2026
SOLUTIONS VERIFIED PREMIUM
◉ Blue Smoke. Answer: this means the engine is burning oil. Could
be caused by worn piston rings
◉ White Exhaust Smoke. Answer: caused by coolant leaking into one
or more cylinders, such as when a head gasket goes bad
◉ Worn valve guides and vacuum readings. Answer: this condition
would cause the vacuum gauge needle to fluctuate at idle, but the
needle would steady when the engine speed is increased.
◉ Weak or broken valve spring and vacuum readings. Answer: this
condition would cause the vacuum gauge needle to fluctuate or jump
from low to high readings
◉ Causes of Engine detonation (knock). Answer: 1. A lean air/fuel
mixture
2. Advanced ignition timing
3. Excess carbon in the combustion chambers
4. A stuck-closed EGR valve
,◉ Intermittent open in the pickup coil leads. Answer: Vehicle with
electronic ignition hesitates and stumbles during acceleration.
Problem goes away when vacuum advance hose (on the vacuum
advance distributor) is disconnected and plugged. What's up with
that?
◉ Timing light with ignition advance meter. Answer: This is the best,
most accurate way to measure spark advance
◉ Causes of "tapping" noise coming from top end of V8 engine.
Answer: could be caused by worn valve train components or
excessive valve train clearance, like a valve needing adjustment
could be an exhaust leak at the manifold/cylinder head junction
◉ DSO reading of disconnected or open spark plug wire. Answer:
this DSO reading would show a higher by comparison spike line
reading when compared to the other spark plugs
◉ DSO reading of closed spark plug gap. Answer: this DSO reading
would show a very low spike line in comparison to the other spark
plugs
◉ Unmetered air entering the engine. More air than the amount for
which the engine is delivering fuel. Answer: Vehicle can be started
, with great difficulty, but lacks power and will not idle. What's going
on?
◉ Crank-no-start diagnosis. Answer: Do not jump to conclusions.
Test until the defective component is identified
◉ Air blowing into crankcase during cylinder leakage test. Answer:
This would indicate worn piston, rings and / or cylinder during a
leakage test
◉ Bubbles in the radiator coolant during cylinder leakage test.
Answer: This would indicate a cracked head, cracked block and/or
blown head gasket during a cylinder leakage test
◉ Fuel Pump Electrical Diagnosis. Answer: Simply having system
voltage at the tank is not enough to condemn a pump. A multimeter
puts virtually no load on a pump circuit. Before energy reaches the
fuel pump, it must pass through the pump harness, pass-through
connector, and pump wiring. A high resistance in any of these places
can keep the pump from running properly. A test light can load the
circuit in place of the pump, to determine if there is a resistance
which will cause a significant drop in voltage available to the pump.
Typical resistance could be from relay contacts which are burned or
have insufficient pressure
SOLUTIONS VERIFIED PREMIUM
◉ Blue Smoke. Answer: this means the engine is burning oil. Could
be caused by worn piston rings
◉ White Exhaust Smoke. Answer: caused by coolant leaking into one
or more cylinders, such as when a head gasket goes bad
◉ Worn valve guides and vacuum readings. Answer: this condition
would cause the vacuum gauge needle to fluctuate at idle, but the
needle would steady when the engine speed is increased.
◉ Weak or broken valve spring and vacuum readings. Answer: this
condition would cause the vacuum gauge needle to fluctuate or jump
from low to high readings
◉ Causes of Engine detonation (knock). Answer: 1. A lean air/fuel
mixture
2. Advanced ignition timing
3. Excess carbon in the combustion chambers
4. A stuck-closed EGR valve
,◉ Intermittent open in the pickup coil leads. Answer: Vehicle with
electronic ignition hesitates and stumbles during acceleration.
Problem goes away when vacuum advance hose (on the vacuum
advance distributor) is disconnected and plugged. What's up with
that?
◉ Timing light with ignition advance meter. Answer: This is the best,
most accurate way to measure spark advance
◉ Causes of "tapping" noise coming from top end of V8 engine.
Answer: could be caused by worn valve train components or
excessive valve train clearance, like a valve needing adjustment
could be an exhaust leak at the manifold/cylinder head junction
◉ DSO reading of disconnected or open spark plug wire. Answer:
this DSO reading would show a higher by comparison spike line
reading when compared to the other spark plugs
◉ DSO reading of closed spark plug gap. Answer: this DSO reading
would show a very low spike line in comparison to the other spark
plugs
◉ Unmetered air entering the engine. More air than the amount for
which the engine is delivering fuel. Answer: Vehicle can be started
, with great difficulty, but lacks power and will not idle. What's going
on?
◉ Crank-no-start diagnosis. Answer: Do not jump to conclusions.
Test until the defective component is identified
◉ Air blowing into crankcase during cylinder leakage test. Answer:
This would indicate worn piston, rings and / or cylinder during a
leakage test
◉ Bubbles in the radiator coolant during cylinder leakage test.
Answer: This would indicate a cracked head, cracked block and/or
blown head gasket during a cylinder leakage test
◉ Fuel Pump Electrical Diagnosis. Answer: Simply having system
voltage at the tank is not enough to condemn a pump. A multimeter
puts virtually no load on a pump circuit. Before energy reaches the
fuel pump, it must pass through the pump harness, pass-through
connector, and pump wiring. A high resistance in any of these places
can keep the pump from running properly. A test light can load the
circuit in place of the pump, to determine if there is a resistance
which will cause a significant drop in voltage available to the pump.
Typical resistance could be from relay contacts which are burned or
have insufficient pressure
