Engine - MIL ON/Misfire DTC's/Driveability Concerns
Article No.04-9-1
05/11/04
^ DRIVEABILITY - ROUGH IDLE, LOW POWER
AND/OR STALL AT IDLE WITH DIAGNOSTIC
TROUBLE CODES (DTCS) P0300-P0304 STORED IN
MEMORY - VEHICLES EQUIPPED WITH 2.0L SPI
ENGINE ONLY
^ ELECTRICAL - MALFUNCTION INDICATOR LAMP
(MIL) ILLUMINATED - DIAGNOSTIC TROUBLE
CODES (DTCS) P0300-P0304 STORED IN
MEMORY - VEHICLES EQUIPPED WITH 2.0L SPI
ENGINE ONLY
FORD:
1997-2002 ESCORT
2000-2002 FOCUS
MERCURY:
1997-1999 TRACER
This article supersedes TSB 02-09-01 to update the service and part information.
ISSUE
Some vehicles equipped with the 2.0L SPI engine may exhibit a malfunction indicator lamp (MIL) illuminated and diagnostic trouble codes (DTCs) P0300 through P0304 stored in memory. The vehicle may also have a rough idle or reduced power condition, and/or may stall at an idle. This may be caused by sticking exhaust valves due to excessive carbon build-up.
ACTION
Check for faulty fuel injectors and ignition wires. One or more exhaust valves may be temporarily sticking due to carbon build-up between the valve stem and guide. If the diagnostic checks point to a sticking exhaust valve, the cylinder head assembly may need to be replaced with a new level cylinder head assembly with revised valve guides, revised exhaust valves will also need to be installed to help prevent carbon build-up. Refer to the following Service Procedure for details.
SERVICE PROCEDURE
NOTE
THIS PROCEDURE APPLIES ONLY TO THE 2.0L SPI ENGINE.
This condition usually results in misfire when the engine returns to idle after running approximately 2000 RPM or higher.
1. Use the worldwide diagnostic system (WDS) to test for Power Balance with the engine at idle. Check for cylinder misfire. If misfire is occurring constantly, go to Step 3. If misfire is not occurring, attempt to induce misfire by performing the following step:
a. Apply the parking brake and keep the transmission in Park or Neutral. Bring the engine to approximately 2800 RPM and hold for one (1) minute. Check the WDS Power Balance display while holding engine speed constant. Allow the engine to return to idle and watch the WDS Power Balance display for a misfiring cylinder.
2. If WDS Power Balance indicates a misfiring cylinder with the previous test, one or more exhaust valves may be intermittently sticking due to carbon build-up between the valve stem and guide. Replace the cylinder head with the new level cylinder head with revised valve guides. Once stock is exhausted of the loaded cylinder heads, the cylinder head will come bare so revised exhaust valves will need to be installed in place of the original valves. The revised valve guides and exhaust valves help prevent carbon build-up. Consult the appropriate model year Workshop Manual for removal and installation procedures for the Cylinder Head Assembly.
3. If WDS Power Balance did not indicate a misfiring cylinder with the previous test or a misfire is occurring constantly, the misfire may not be due to a sticking exhaust valve. Refer to the appropriate model year Powertrain Control/Emissions Diagnosis (PC/ED) Service Manual for further diagnosis. Other possible causes may be, worn or arcing ignition wires, base engine compression, fuel injectors, fuel injector harness resistance or PCM injector driver signal. Perform diagnosis and repair as necessary.
4. After completing either Step 2 or Step 3, replace the PCV Valve (YS4Z-6A666-AC) (Motorcraft EV-244) on model year 2000-2002 Focus or 2000-2002 Escort. Vacuum fluctuations from engine misfire may prematurely wear the PCV valve on those applications.
NOTE
THE CYLINDER HEAD ASSEMBLIES LISTED BELOW WILL BE BARE CASTINGS ONCE SUPPLY OF LOADED HEADS IS EXHAUSTED, IN MOST CASES IT WILL BE NECESSARY TO REPLACE ONLY THE PARTS LISTED BELOW, ALL OTHER PARTS CAN BE REUSED.
Service and Part Number Charts
OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS: Eligible Under Provisions Of New Vehicle Limited Warranty Coverage
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