Panduan Singkat Mencari Penyebab Kerusakan Mobil Bensin Berdasarkan Gejala yang Timbul (yg berhubungan dg fuel, emisi, & engine management system)

Troubleshooting mungkin dapat diartikan secara bebas sebagai mencari sebab permasalahan.
Berikut ini adalah panduan troubleshooting permasalahan pada mobil bensin berdasarkan gejala-gejala yang timbul. Panduan ini dibuat khusus untuk mobil yang memakai engine management system. Namun, bisa juga Anda gunakan untuk mobil-mobil konvensional sebagai panduan umum. Bedanya, mobil konvensional tidak memiliki sensor-sensor ataupun ada yang tidak memakai fuel injektor, melainkan memakai karburator.

MAP = Manifold Absolute Pressure
MAF = Manifold Air Flow
EGR = Exhaust Gas Regulator
TPS = Throttle Position Sensor
IAC = Idlespeed Control


Engine noise
- Hiss (bunyi mendesis) – vacuum leaks
- Adanya loncatan busur api atau Electrical arching (snapping noise)

Engine mau distart tetapi engine tidak mau hidup
- charcoal canister full of fuel
- faulty MAP, MAF, or coolant sensor or circuit
- EGR valve stuck open
- Faulty canister vent valve
- Fuel pressure lack
- Fuel empty
- Water in fuel
- Aki soak (putaran starter pelan/lemah)
- Busi kotor
- Severe vacuum leak
- Injektor mampet
- Sirkuit start rusak
- Faulty air flow sensor
- IAC valve defective

Engine sulit hidup – dingin
- Leaking injectors

Engine sulit hidup – panas
- Aki soak
- Air filter sumbat
- Defective coolant sensor/circuit
- Defective intake air temperature sensor/circuit
- Defective MAP or MAF
- Faulty TPS or circuit
- Aki kotor
- Ground jelek
- Busi kotor
- Fuel pressure
- Air flow sensor faulty
- PCV valve stuck open
- Vacuum/air leak

Engine hidup tetapi tidak mau jalan
- Faulty canister vent valve
- EGR stuck open
- Coil & alternator loose
- Intake manifold vacuum leaks
- Airflow kurang

Engine “lopes” idle, rough, erratic
- Air filter clogged
- Throttle plate/bore kotor
- EGR
- Vacuum leak
- Air leak in intake duct/manifold
- IAC
- Lean injector
- Rich injector
- Fuel pump
- Cold only = PCV stuk
- Warm only = TPS or MAF

Engine mati saat langsam/idle.
- Busi kotor/gap
- Kabel busi
- EGR valve
- Fuel filter/line
- Vacuum leak
- Incorrect timing
- Kompresi silinde low/sinjal

Excessive idle speed
- vacuum leak
- throttle linkage macet

Engine misses throughout driving speed range
- Fuel filter kotor
- Fuel pump pressure
- Busi
- Kabel busi
- Kompresi piston lemah
- Ignition system
- Vacuum leak
- Lean injector

Hesitation/stumbles/stalls kalau pedal gas diinjak/ditekan untuk akselerasi.
- Busi kotor
- Fuel filter
- TPS
- Air temperature sensor
- MAP
- Air leak di manifold
- MAF
- Throttle plate/bore kotor
- Ignition coil/kabel
- Fuel pump pressure
- Fuel injektor

Engine lack power/sluggish performance
- Air filter mampet
- Exhaust mampet
- Vacuum leak
- EGR valve stuck open
- MAP
- Busi gap
- Fuel filter
- Vacuum leak
- Injektor

Stall on decal/coming to a quick stop
- EGR valve stuck/leakage around base
- TPS
- Idle air control valve malfunction
- Fuel filter
- Gap busi
- Vacuum leak

Surging at steady speed
- Air filter
- Vacuum leak
- Air leak
- EGR valve stuck/leak at base
- O2 sensor
- TPS
- MAF, MAP
- Loose fuel injector connector
- TCC (torque converter connector)
- Fuel pressure, pump
- Lean injector
- Defective computer/information sensor

Engine tidak mau mati (diesel/runs on) saat kunci kontak di-off-kan atau idle speednya terlalu tinggi
- vacuum leak
- EGR Valve
- Excessive engine operation temperature, overheating
- Incorrect spark plug selection

Engine "nembak" /Back firing (baik dari intake dan/atau exhaust)
- vacuum leak di PCV or canister purgeline
- vacuum leak at fuel injector, intake manifold air control valve or vacuum line
- Faulty secondary ignition system (busi retak, kabel)
- EGR
- Emission control system
- Faulty air valve
- Valve clearance
- Damaged valve spring, sticking, burned check by vacuum gage

Bensin boros
- air filter mampet
- PCV
- O2 sensor
- Timing
- Fuel leak
- Injector worn/damage
- Rem mampet
- Ban kempes/kurang angin

Detonasi (spark knock)
- EGR valve inoperative
- Vacuum leak
- Busi
- Knck sensor
- Fuel quality

Exhaust banyak asapnya
- Black (rich): air filter, intake duct mampet, O2 sensor
- Blue (burning oil): PCV valve stuck, PCV filter
- Brown/yellow (lean): fuel filter, lean injector

Bau bensin
- tank overfilled
- tank cap gasket
- lines leaking
- injector stuck open
- injector leak internally
- injector leak externally
- EVAP canister filter in EEC mampet
- Vapor leaks from Evaporative Emission Control System lines


Beberapa Tools yang sangat baik untuk dimiliki karena akan sangat membantu dalam troubleshooting:

- stetoskop khusus otomotif (ujungnya yang ditempelkan berbentuk panjang seperti tubing, sedangkan yang punya dokter, yang ditempelkan berbentuk bulat)
- Analyzer
- Vacuum gage
- termometer laser
- timing light
- power cylinder pessure gage

trims