contains: MASS AIR FLOW SENSOR- Lean Driveability Symptoms Aluminum Cylinder Head - Removal From Engine Cylinder Head Straightedge Surface Check Inspection For Damage and Cleaning Procedure Installation Onto the Cylinder Block Surface Temperature Gauge - Fluctuation/Inaccurate Heater Core - Repeated Failure Audio System - Whining/Buzzing Noise From Speakers Stinky A/C A/T - 4EAT Delayed Engagement Cooling Fan and/or Gauges - Erratic Operation :!: MAF ACTION Follow the diagnostic procedures described in the following Service Tip. The revised diagnostic procedure is a more accurate means of diagnosing the symptoms. SERVICE TIP MASS AIR FLOW (MAF) DISCUSSION MAF sensors can get contaminated from a variety of sources: dirt, oil, silicon, spider webs, potting compound from the sensor itself, etc. When a MAF sensor gets contaminated, it skews the transfer function such that the sensor over-estimates air flow at idle (causes the fuel system to go rich) and under-estimates air flow at high air flows (causes fuel system to go lean). This means Long Term Fuel Trims will learn lean (negative) corrections at idle and learn rich (positive) corrections at higher air flows. If vehicle is driven at Wide Open Throttle (WOT) or high loads, the fuel system normally goes open loop rich to provide maximum power. If the MAF sensor is contaminated, the fuel system will actually be lean because of under-estimated air flow. During open loop fuel operation, the vehicle applies Long Term Fuel Trim corrections that have been learned during closed loop operation. These corrections are often lean corrections learned at lower air flows. This combination of under-estimated air flow and lean fuel trim corrections can result in spark knock/detonation and lack of power concerns at WOT and high loads. One of the indicators for diagnosing this condition is barometric pressure. Barometric pressure (BARO) is inferred by the Powertrain Control Module (PCM) software at part throttle and WOT (there is no actual BARO sensor on MAF-equipped vehicles, except for the 3.8L Supercharged engine). At high air flows, a contaminated MAF sensor will under-estimate air flow coming into the engine, hence the PCM infers that the vehicle is operating at a higher altitude. The BARO reading is stored in Keep Alive Memory (KAM) after it is updated. Other indicators are Long Term Fuel Trim and MAF voltage at idle. NOTE THE FOLLOWING PROCEDURE MAY ALSO BE USED TO DIAGNOSE VEHICLES THAT DO NOT HAVE FUEL SYSTEM/HO2S SENSOR DTCS. Symptoms ^ Lack of Power ^ Spark Knock/Detonation ^ Buck/Jerk ^ Hesitation/Surge on Acceleration ^ Malfunction Indicator Lamp (MIL) Illuminated - DTCs P0171, P0172, P0174, P0175 may be stored in memory OBDII DTCs ^ P0171, P0174 (Fuel system lean, Bank 1 or 2) ^ P0172, P0175, (Fuel system rich, Bank 1 or 2) ^ P1130, P1131, P1132, (HO2S11 lack of switching, Bank 1) ^ P1150, P1151, P1152, (HO2S21 lack of switching, Bank 2) OBDI DTCs ^ 181, 189 (Fuel system lean, Bank 1 or 2) ^ 179, 188 (Fuel system rich, Bank 1 or 2) ^ 171, 172, 173 (HO2S11 lack of switching, Bank 1) ^ 175, 176, 177 (HO2S21 lack of switching, Bank 2) ^ 184, 185 (MAF higher/lower than expected) ^ 186, 187 (Injector pulse width higher/lower than expected) :!: CYLINDER HEAD: :arrow: Aluminum Cylinder Head - Removal From Engine WARNING ALUMINUM CYLINDER HEADS ARE HIGHLY POLISHED AND MUST BE HANDLED WITH EXTREME CARE. AFTER REMOVING THE HEAD BOLTS, WITHDRAW THE HEAD FROM THE ENGINE COMPARTMENT. USE EXTREME CARE NOTING THAT THE GASKET SURFACE OF THE HEAD COULD BE DAMAGED ON THE WAY OUT OF THE VEHICLE IF ALLOWED TO HIT AGAINST OTHER ENGINE COMPONENTS. ONCE REMOVED, PLACE THE HEAD ON A BENCH, GASKET SIDE UP, USING A PIECE OF CLEAN CARDBOARD ON THE BENCH SURFACE UNDERNEATH. DO NOT SLIDE THE HEAD GASKET SURFACE ALONG THE BENCHTOP OR DAMAGE WILL OCCUR. NOTE SOME ENGINES REQUIRE A "DE-TORQUING" PROCEDURE OF THE CYLINDER HEAD BOLTS. CONSULT WITH THE APPROPRIATE MODEL YEAR WORKSHOP MANUAL FIRST, AS THIS PROCEDURE IS USUALLY DONE ON FOUR-VALVE ENGINES. HOWEVER, ALL ALUMINUM HEADS ARE PRONE TO WARPAGE DURING REMOVAL IF TAKEN OFF WHEN HOT OR WARM. THE ENGINE SHOULD BE COOLED SUFFICIENTLY BY THE TIME THE HEADS ARE ACCESSIBLE DURING TEARDOWN. ALLOW AN ADEQUATE COOL DOWN PERIOD. NOTE IN SOME ENGINE APPLICATIONS, IT MAY BE NECESSARY TO "RUBBER BAND" A FEW OF THE HEAD BOLTS TOGETHER DUE TO TIGHT CLEARANCES OF THE HEAD NEAR HEATER/AC PLENUMS AND THE BODY COWL. THIS WILL ALLOW THE BOLTS TO CLEAR THE BLOCK DECK AS THE HEAD IS WITHDRAWN FROM THE VEHICLE. Place CLEAN shop towels over the cylinder block bores to prevent further contamination from reaching internal parts and surfaces. If a towel is to be removed, do it SLOWLY . Debris collected on the towel can fall on the engine if care is not exercised as it is removed. Gasket surfaces are machined to near-mirror surface quality. Scratches, dents, gouges, and other impressions may allow oil, coolant, and compression gases to leak into other sealed cavities and/or the atmosphere. Surface imperfections deteriorate the head gasket's ability to seal effectively. Contamination on these surfaces will cause leaks from "shimming" the head even under full head bolt torque. Contamination will also cause marks on the polished gasket surface, creating a leak path. :!: Engine - Cylinder Head Straightedge Surface Check ISSUE Aluminum cylinder heads and blocks require flatness checks prior to gasket installation to ensure the component part is not out of factory specification. The surface quality (finish) of the cylinder head gasket surface is machined to close tolerances which enable an effective sealing joint for the MLS (multi-layered steel) gasket. ACTION Ensure all head gasket surfaces are clear of any gasket debris, RTV, oil, and coolant using Motorcraft Silicone Gasket Remover (ZC-30) and Motorcraft Metal Surface Prep (ZC-31). Use a lint free rag to mop up the deck surfaces. Shop vacuums are unacceptable for mop up as the cleaner is volatile. The block or head surface must be clean and dry before running a flatness check. SERVICE INFORMATION Use a straightedge that is calibrated by the manufacturer to be flat with 0.0002 inches (0.005 mm) per running foot length. For example, the straightedge may be 24 inches (61 cm) long. That means the machined edge must be flat within 0.0004 inches (0.010 mm) from end to end. Special care is required to ensure the tool is not damaged in handling or storage. Be sure that the machined surface is free of nicks and dents. If these properties are found, the cost of tool re-calibration most likely will exceed the cost of a new straightedge. Machine shops may not be able to hold the specified tolerance within the original cost of the straightedge. When checking for flatness, avoid running the feeler gauge butt end against the straightedge. This action will curl or warp the feeler gauge leaf and prevent entry under the straightedge. Erroneous readings will result. Instead, lay the feeler gauge leaf on the suspect area, placing the straightedge on top of the leaf. A very easy pull or looseness of the leaf under the edge will indicate a depression in the surface. Turn the edge 90 degrees to the area just checked. Confirm any suspicion by checking the area more than one time. Figure 1 demonstrates a 12 point check system using a grid format on a 4 cylinder bank. It is important to note that a localized area of approximately 1.0 to 20 sq.in. will influence the effectiveness of the MLS gasket sealing capability. Depressions or marks measured to be over 0.001 inch deep will not seal properly. The overall flatness check (head end to other end) is not as critical. :arrow: Inspection For Damage and Cleaning Procedure The overall straightness of the cylinder head and block face is held within very tight specification. Defects known as "waviness" or "depressions" cannot be surface machined out with ordinary equipment. Machining must meet manufacturer's specification on surface finish quality and be less than 0.001" inch (0.025 mm) level as measured under a known quality straightedge using a feeler gauge. If the engine has been overheated the cylinder head may have been damaged or warped. Re-surfacing will not correct this damage. The head must not contain any impressions on its sealing surface deeper than 0.001" (0.025 mm). There must not be any scratches or gouges present, especially those which track to another sealing cavity or to the atmosphere. Ensure that the mating cylinder block surface is completely free of solid contamination, corrosion, and fluids. Use Motorcraft Metal Surface Cleaner, F4AZ-19A536-RA or equivalent, to rid the surface of any material, which could later interfere with the gasket's sealing ability. WARNING UNDER NO CIRCUMSTANCES ARE ANY ALUMINUM GASKET SURFACES TO BE CLEANED USING RAZOR BLADES, ROTARY ABRASIVE DEVICES INCLUDING ROLOC AND 3M BRANDED SCOTCHBRITE PRODUCTS, ROTARY WIRE BRUSHES, SINGLE HANDLED WIRE BRUSHES, HAND ABRASIVE SUCH AS SANDPAPER OR EMERY CLOTH, OR ANY CARBON STEEL BLADE. THESE TOOLS ARE PROVEN TO CUT AND DAMAGE ALUMINUM AND WILL DISRUPT THE POLISHED FINISH. ABRASIVE PARTICLES ARE ALSO SUSCEPTIBLE TO ENTERING THE ENGINE CAVITIES AND MAY CAUSE INTERNAL ENGINE DAMAGE. THE ONLY TOOLS ACCEPTABLE ARE PLASTIC AND WOOD SCRAPERS COMBINED WITH USE OF MOTORCRAFT METAL SURFACE CLEANER, F4AZ-19A536-RA, OR EQUIVALENT SOLVENT. The original head bolts are to be discarded. Only new head bolts are acceptable for use in a head gasket repair. Use of old bolts can cause clamp load failure because they were stretched from the last torquing procedure either from the plant or a previous field repair. The new head bolt shanks and threads should be thoroughly cleaned, dried, and lightly lubricated. Oil the bolts and let oil drip for a minimum of 5 minutes. Use of too much oil may cause hydraulic lockup in the bolt hole. The corresponding bolt holes in the cylinder block must be free of contamination consisting of dirt particles, coolant, and oil. Bolts can mechanically or hydraulically lock on top of these materials and cause for poor clamping of the cylinder head gasket. Use very lightly compressed air to blow out the bolt holes. Use care to prevent debris from scattering over the internal engine surfaces. To clean the cylinder block gasket surface, a plastic or wood scraper in combination with Motorcraft Metal Surface Cleaner, F4AZ-19A536-RA, or equivalent solvent can be used with a portable shop vacuum. Move the scraper toward the vacuum nozzle to direct loosened material quickly away from the block surface. It is not necessary to expect aluminum head surfaces to be shiny and bright after the vehicle has been in service. Sanding, scraping, or polishing will create surface depressions that cause leaks. The surface is expected to be flat within 0.001" (0.025 mm) and free of dirt, metal chips, and liquid contaminants. Any staining of the metal surface is considered normal. Machining of aluminum heads and blocks is an unacceptable field practice for quality control purposes of flatness and surface finish standards. Removing material will also raise the risk of internal reciprocating components striking each other, as well as changing the emissions calibration of the engine. Machining practices of aluminum blocks and heads are not reimbursable. Ford Remanufacturers are authorized to perform this procedure and have the necessary equipment to put the specified surface finish on the head within original factory limits. :arrow: Installation Onto the Cylinder Block Surface WARNING ANY GASKET SEALING AIDS WHICH ARE NOT LIMITED TO, AND INCLUDE AVIATION CEMENT, COPPER SPRAYS, OR GLUES ARE NOT TO BE USED. THE GASKET MUST BE FITTED DRY WITHOUT SUPPLEMENTAL SEALING AIDS. ATTEMPTS TO SEAL WITH THESE COMPOUNDS WILL CAUSE HEAD SHIMMING AND/OR NEW LEAK PATHS. THESE COMPOUNDS HAVE ALSO BEEN KNOWN TO CAUSE EMISSIONS SENSORS TO FAIL THEREBY TRIPPING FAULT CODES IN THE PCM. Ensure that all surfaces of the cylinder block, cylinder head, and gasket are fully free of any solid or liquid contamination and have been prepared for assembly using Motorcraft Metal Surface Cleaner, F4AZ-19A536-RA, or equivalent solvent. Also ensure that any residual dirt on the engine was removed successfully from the surrounding areas of the block to head face of the head and the block. Using Workshop Manual procedures, assemble the head to the block carefully. Do not allow the gasket surfaces to scrape or bang against other engine parts. The head may pick up material along the way, if this is allowed. Once in place, with dowels properly aligned to the head and ensuring that the head is fully square, seated, and resting on the block deck in a level condition, install new "torque-to-yield" cylinder head bolts to a finger tight condition. Refer to the appropriate model year Workshop Manual for the procedure to torque the head bolts in the correct sequence and at the intervals specified. Failure to follow these instructions may result in a warped head, and damaged head bolt threads. Do not use "cheater pipes" on torque wrenches. Use a known quality, calibrated torque wrench. Pull evenly and steady on each bolt. Do not exert side pressures on the bolt hex, which can disrupt the integrity of the bolt head and give a false reading on the final torque value of the fastener. Once the engine is fully reassembled, be sure that fluid levels have been topped off as required for the operation. When the engine is ready for starting, ensure that the engine 6i1 pump is (was) primed properly and is in a "ready to start" condition with all engine oil galleys having been charged with oil. WARNING DO NOT RACE THE ENGINE UPON INITIAL STARTUP. MAINTAIN ENGINE IDLE TO BUILD OIL PRESSURE. USE OF A MECHANICAL PRESSURE GAUGE WILL ENSURE THAT OIL FLOW HAS DEVELOPED ON THE PUMP'S PRESSURE SIDE. A DEFECTIVE GAUGE OR LIGHT IN THE INSTRUMENT PANEL WILL NOT VERIFY PRESSURE HAS BEEN OBTAINED. SEVERE INTERNAL ENGINE DAMAGE WILL RESULT IF PRESSURE IS NOT OBSERVED AND STEADILY MAINTAINED. Allow a warm up period, which brings the engine to normal operating temperature. Check for leaks around the gasket joints of the head, front cover, and associated component parts. The vehicle should be road tested within normal guidelines to raise the engine to operating temperature and verify the repair is sound. Shut down the engine, allow for a cool-down and drain-back period to enable fluids to return to levels. Check fluid levels using owner guide recommendations (dipstick, sight gages, etc.). :!: Temperature Gauge - Fluctuation/Inaccurate ISSUE: Some vehicles may show temperature gauge fluctuations and/or inaccurate (high) readings (affected engines are 3.0L/4.0L Ranger. 4.0L Explore and 1.9L Escort/Tracer). The inaccurate (high) readings may result in a customer concern with the perception of engine overheating. This is caused by Gauge/Sender design characteristics which create a sensitive gauge indication. ACTION: Replace the gauge and sender with a new Temperature Indication Service Kit. Refer to the following for Additional Concerns and Service Procedure for details. ADDITIONAL CONCERNS Please verify the following two (2) concerns before implementing the fix for the above concern. 1. Perform cooling system diagnosis per TSB 93-24-8. 2. Vehicles built from 1/1/93 to 4/1/93 may experience high temperature gauge indications which may have been due to the installation of improperly manufactured temperature sending units. The customer concern is that the gauge indication is beyond the letter "L" in the word "NORMAL". If this condition occurs, inspect the temperature sender for an "A3" stamped date code on the hex of the sending unit. If an "A3" unit is found, replace with "NON-A3" service stock. :!: Heater Core - Repeated Failure ISSUE Some vehicles may exhibit (repeat) heater core leaks. This may be caused by a chemical reaction called electrolysis. Electrolysis involves an ion exchange between the heater core and engine coolant which can result in a breakdown of the heater core material. This is similar to the operation of a battery. ACTION Check for electrolysis on any vehicle with a heater core failure. If electrolysis is verified, flush the coolant and follow additional steps as required. Refer to the following Service Procedure for details. SERVICE PROCEDURE Electrolysis Inspection If there is a condition of a heater core leaking or repeal heater core leak, check for electrolysis using the following procedure: 1. To check for electrolysis use a DVOM set on DC volts. Place the positive probe of the meter in the engine coolant and the negative probe on the negative battery post. 2. Adjust engine throttle to 2000 RPM to properly get coolant flow and true electrolysis voltages. 3. If more than .4V is recorded, flush the coolant and recheck (follow guidelines in TSB 98-23-16 for Cougar). See Coolant Fill Procedure below to remove trapped air on 4.6/5.4/6.8L modular engines. NOTE EXPORT MARKETS, BE SURE THE WATER IS DESALINATED. 4. If there is still excessive voltage present in the coolant, check the engine to body/battery grounds. Also, verify proper grounding of any aftermarket electrical/electronic equipment which has been installed into the vehicle. Improperly grounded electrical devices can cause electrolysis to occur. 5. If the condition is still present after the grounds have been checked, it may be necessary to add extra grounds to the heater core and engine. A hose clamp can be used to secure a 16 AWG stranded copper wire to the heater core inlet tube. The other end should be secured to an EXISTING FASTENER on the body sheet metal. Extra grounds to the engine should be attached between EXISTING FASTENERS on the engine and body sheet metal. Verify continuity of any added grounds to the negative battery terminal. 6. If the condition is still present, add a restrictor (part F1UZ-18D406-A) on the inlet hose with the arrow facing the direction of coolant flow (toward heater core). Cut the line and install with 2 hose clamps. It is important that the restrictor be installed in the right direction of flow and as close to the engine block as possible (not near the heater core itself). :!: Audio System - Whining/Buzzing Noise From Speakers ISSUE A "whining"/"buzzing" noise in the speakers of the entertainment radio or two-way radio on vehicles with an in-tank electric fuel pump may be caused by electrical noise from the fuel pump. ACTION Install an electronic noise Radio Frequency Interference (RFI) Filter (F1PZ-18B925-A) on the fuel pump inside the fuel tank. Refer to the following Test Procedure to confirm that the concern exists, then refer to the Service Procedure for repair details. NOTE IF THE VEHICLE HAS AN ELECTRONIC RETURNLESS FUEL SYSTEM, DO NOT INSTALL A RFI FILTER INLINE TO THE FUEL PUMP. ONLY VEHICLES WITH MECHANICAL RETURNLESS FUEL SYSTEMS (PRESSURE REGULATOR IN THE TANK), OR SYSTEMS WITH THE PRESSURE REGULATOR ON THE FUEL RAIL SHOULD BE APPROVED FOR THE RFI FILTER INSTALLATION. NOTE SOME LIGHT TRUCKS REQUIRE ONE (1) RFI FILTER FOR EACH IN-TANK ELECTRIC FUEL PUMP ON MULTI-TANK VEHICLES. NOTE THIS TSB DOES NOT INCLUDE TAURUS FLEXIBLE FUEL VEHICLES (FFVS) OR 1999 RANGER 3.0L FFVS. TEST PROCEDURE Fuel pump radio noise is relatively constant and changes only slightly with vehicle speed. If the frequency of the noise varies or the noise comes and goes with the vehicle speed, then it is not the fuel pump and this fix will not be effective. The following procedure will help determine if the fuel pump is the cause of the radio noise: 1. Turn on the radio before the key is turned on (assuming the radio will operate without the ignition key - you may need to put the ignition key in the Accessory position). 2. Turn the ignition key to the Run position (do not start the engine). 3. The fuel pump should run for about 1 second with the key in the Run position with the engine not running. Listen for noise in the radio. If noise is present while the pump is running and stops when the pump stops, then the noise is being generated by the pump and this procedure should help. :!: stinky A/C ISSUE Musty and mildew type odors may come from the air conditioner and heater system. This odor is caused by mildew-type fungi growth in the A/C evaporator. It is most noticeable when the A/C is first turned on. ACTION A new Disodorizer(R) which encapsulates the mildew is now available to reduce these odors. This is a seasonal repair. Engineering effort to provide a long term repair for A/C odors will continue. Apply the Ford A/C Disodorizer(R) product (F6AZ-19G210-AA or YN-18) to the A/C system as directed in the following A/C Odor Treatment Procedure. WARNING : AVOID CONTACT WITH EYES AND SKIN. CONTACT WITH EYES AND SKIN WILL CAUSE IRRITATION. WEAR SAFETY GLASSES WHEN USING. WARNING : THIS PROCEDURE SHOULD ONLY BE PERFORMED IN WELL VENTILATED AREAS. OPEN ALL WINDOWS AND DOORS OF THE VEHICLE. LEAVE DOORS AND WINDOWS OPEN DURING THE ENTIRE PROCEDURE. AVOID BREATHING VAPORS. WARNING : AVOID FLAMES, SPARKS OR LIT TOBACCO PRODUCTS. THIS PRODUCT IS COMBUSTIBLE. WARNING : READ ALL INSTRUCTIONS AND WARNINGS PACKAGED WITH THE DISODORIZER(R). :!: A/T - 4EAT Delayed Engagement FORD: 1995-97 ESCORT LINCOLN-MERCURY: 1995-97 TRACER ISSUE: Some vehicles may exhibit an engagement delay when shifting the vehicle from "Park" to "Reverse" and/or "Drive" at initial driveaway. This may be caused by transaxle fluid draining from the torque converter while the vehicle is parked for more than 12 hours. ACTION: Install a revised valve body to reduce the possibility of fluid draining back from the torque converter. Refer to the following Service Procedure for details. SERVICE PROCEDURE NOTE :THIS TSB ARTICLE DOES NOT APPLY TO VEHICLES PARKED FOR AN EXTENDED PERIOD OF TIME (3 DAYS OR MORE). 1. Verify the transaxle fluid level is within specification at normal operating temperature with the engine running. 2. Turn the engine off and wait a minimum of 5 minutes and record the fluid level while on a flat surface. Park the vehicle overnight. Recheck the oil level with the engine off. If the oil level rises 30 mm or more, verify the concern at initial engagement. 3. If the concern is present, replace the valve body with revised Valve Body (F7CZ-7A100-AA). Refer to the appropriate Escort/Tracer Service Manual. :!: Cooling Fan and/or Gauges - Erratic Operation FORD: 1997 ESCORT LINCOLN-MERCURY: 1997 TRACER ISSUE: The gauges and/or cooling fan may experience irregular operation. This may be caused by high resistance at the ground attachment. ACTION: Remove the ground screw and remove the paint underneath the ground screw attachment. This should reduce the possibility of high resistance. Refer to the following Service Procedure for details. SERVICE PROCEDURE 1. Locate ground circuit # G146 in the engine compartment below the engine compartment fuse box on the body rail. The ground eyelet is bent at a 90 degree angle and its location is identified in the 1997 Escort/Tracer Electrical/Vacuum Troubleshooting Manual (EVTM), Page 151-1, Location/Zone D10. 2. Remove the ground screw. 3. Remove some of the paint at the point where the eyelet contacts the sheet metal. 4. Reinstall the ground eyelet and the screw.