fuel consumption VOLKSWAGEN CORRADO 1993 Repair Manual

H - TESTS W/O CODES
Article Text (p. 2)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:11PM
* For Cabriolet, see: D - ADJUSTMENTS
* For Corrado SLC, see: D - ADJUSTMENTS
* For EuroVan, see: D - ADJUSTMENTS
* For Fox, see: D - ADJUSTMENTS
* For Golf, GTI, Jetta, see: D - ADJUSTMENTS
* For Passat GL 2.0L 4-Cylinder, see: D - ADJUSTMENTS - 4-CYL
* For Passat GLX 2.8L VR6, see: D - ADJUSTMENTS - VR6
I - SYS/COMP TESTS ARTICLES MENU
NOTE: For the appropriate I - SYS/COMP TESTS article, go to:
* For Cabriolet, see: I - SYSTEM/COMPONENT TESTS
* For Corrado SLC, see: I - SYSTEM/COMPONENT TESTS
* For EuroVan, see: I - SYSTEM/COMPONENT TESTS
* For Fox, see: I - SYSTEM/COMPONENT TESTS
* For Golf, GTI, Jetta, see: I - SYSTEM/COMPONENT TESTS
* For Passat GL 2.0L 4-Cylinder, see:
I - SYSTEM/COMPONENT TESTS - 4-CYL
* For Passat GLX 2.8L VR6, see:
I - SYSTEM/COMPONENT TESTS - VR6
SYMPTOMS
SYMPTOM DIAGNOSIS
Symptom checks cannot be used properly unless the problem is
actually happening while the vehicle is being tested. To reduce
diagnostic time, ensure battery voltage is okay and starter motor
turns engine over before attempting to diagnose a symptom.
Check engine mechanical condition (compression pressure,
valve timing, etc.), wiring harness and connections (terminals not
corroded or pushed back), and vacuum hose (not disconnected or
leaking).
Also check for correct tire sizes, as recommended by
manufacturer. Ensure wheels rotate freely (brake drag or bad wheel
bearings). Ensure no speed reducing accessories are installed.
Symptoms available for diagnosis include the following.
* Engine Does Not Start Or Is Difficult To Start When Cold
* Engine Does Not Start Or Is Difficult To Start When Warm
* Uneven Idle Or No Idle With Cold Engine Or During Warm-Up
* Engine Starts But Stalls
* Idle Speed Exceeds Specification
* Poor Acceleration With Cold Engine Or During Warm-Up
* Engine Stalls While Driving
* Poor Performance
* Engine Run-On (Dieseling)
* High Fuel Consumption
* Engine Knock
* Engine Runs Unevenly Over Entire Speed Range

H - TESTS W/O CODES
Article Text (p. 5)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:11PM
ENGINE STALLS WHILE DRIVING
* Check fuel pump.
* Check auxiliary air intake system.
* Check injector fuel pressure and volume.
* Check idle and full throttle switches.
* Check intake air preheating system.
* Check ignition timing, spark plugs, distributor, secondary
ignition wiring and coil.
POOR PERFORMANCE
* Check fuel pump.
* Check throttle cable adjustment.
* Check auxiliary air intake system.
* Check airflow sensor lever adjustment and control plunger.
* Check throttle potentiometer.
* Check fuel system differential and residual pressures.
* Check injector fuel pressure and volume.
* Check full throttle switch.
* Check mass airflow sensor (if equipped).
* Check intake air preheating system.
* Check catalytic converter.
* Check ignition timing.
ENGINE RUN-ON (DIESELING)
* Check fuel evaporative frequency solenoid(s).
* Check fuel system for leaks.
* Check cold-start valve.
* Check injector fuel pressure and volume.
* Check airflow sensor lever adjustment and control plunger.
HIGH FUEL CONSUMPTION
* Check fuel system for leaks.
* Check oxygen sensor control circuit.
* Check cold-start valve.
* Check injector fuel pressure and volume.
* Check airflow sensor lever adjustment and control plunger.
* Check throttle potentiometer.
* Check injector fuel pressure and volume.
* Check full throttle switch.
* Check mass airflow sensor (if equipped).
* Check intake air preheating system.
* Check exhaust system for leaks (between cylinder and
oxygen (O2) sensor).
* Check ignition timing.
ENGINE KNOCK
* Check knock sensors (if equipped).

TROUBLE SHOOTING - BASIC PROCEDURES
Article Text (p. 29)
1993 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Wednesday, March 22, 2000 09:26PM
Detonation advanced See TUNE-UP
Faulty ignition system Check ignition timing,
See TUNE-UP
Spark plugs loose or Retighten or replace
faulty plugs
Fuel delivery system Inspect lines, pump and
clogged filter for clog
EGR valve inoperative Replace EGR valve
PCV system inoperative Inspect and/or replace
hoses or valve
Vacuum leaks Check vacuum system and
repair leaks
Excessive combustion
chamber deposits Remove built-up
deposits
Leaking, sticking or Inspect and/or replace
broken valves valvesÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄExternal Oil Fuel pump improperly seated Remove pump, replace
Leakage or worn gasket gasket and seat
properly
Oil pan gasket broken or Straighten pan and
pan bent replace gasket
Timing chain cover gasket Replace timing chain
broken cover gasket
Rear main oil seal worn Replace rear main oil
seal
Oil pan drain plug not Remove and reinstall
seated properly drain plug
Camshaft bearing drain Remove restriction
hole blocked
Oil pressure sending Remove and reinstall
switch leaking sending switch
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄExcessive Oil Worn valve stems or guides Replace stems or
Consumption guides, See ENGINES
Valve "O" ring seals Replace "O" ring seals,
damaged See ENGINES
Plugged oil drain back holes Remove restrictions
Improper PCV valve Replace PCV valve
operation
Engine oil level too high Remove excess oil
Engine oil too thin Replace thicker oil
Valve stem oil deflectors Replace oil deflectors
damaged
Incorrect piston rings Replace piston rings,
See ENGINES
Piston ring gaps not Reinstall piston rings,
staggered See ENGINES
Insufficient piston ring Replace rings, See
tension ENGINES
Piston ring grooves or oil Replace piston rings,