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Hey guys - does anyone have access to the text of Technical Service Bulletins? I know I can go to alldata and find the TSB # for free, but wondered if anyone cared to share information relating to what was actually written by Ford on how to solve some of the issues people encounter with these cars.

If anyone is able to access the actual text of the TSBs, the ones I'd be interested in are:

01-7-1 APR 01 Rear Suspension - Squeaking Noise Over Bumps

00-21-2 OCT 00 Hood - Difficult to Close

99-11-1 JUN 99 Noise/Vibration/Harshness-TSB Special

98-23-10 NOV 98 Mass Air Flow Sensor Contamination-Service Tip

And the grandpappy of them all:
99-15-3 JUL 99 Cup Holder Not Deep Enough to Hold
Large Cups
:lol:
No, I don't actually need this one. I was surprised it was in there at all. I can't imagine someone actually bringing the car back for this!!

My car actually has these problems, and I'm going to have the warranty work done. However, I'd really like to see what all the hubbub is about and what the dealership plans to do with the car before I take it in. It may be something I can do.

Appreciative of any help, as always.
 

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Here you go, if you do not have them already. If you want me to email to you let me know.

00-21, Publication Date: SEPTEMBER 29, 2000

FORD:
1994-2000 MUSTANG

ISSUE:
Some vehicles may exhibit a hood that is hard to close. This may be cause by a hood latch support bracket that is improperly adjusted.

ACTION:
Adjust the hood latch support bracket. Refer to the following Service Procedure for details.


SERVICE PROCEDURE

1. Loosen the bolt that attaches the pencil bracket to the bottom of the radiator support («Figure 1»).

2. Check to see if the hoodlatch is interfering with the striker (on inside of hood).

a. Gently push hood down after engaging secondary latch and see if the hood is forced sideways in either direction.

b. Inspect the hood latch to see if paint has been chipped off of either corner. This may help to determine if the hood latch is misadjusted.

3. If there is interference between the hood latch and striker, loosen the three (3) fasteners in the hood latch support bracket that attaches it to the radiator support (one on the top side and two on the forward side) («Figure 2»).

4. Move the hood latch support bracket approximately 2mm in the opposite direction of the interference and tighten the top fastener.

5. Perform Step 2 to see if the interference condition has been eliminated; if not, repeat Step 4 until the hood latch freely engages the striker.

6. Secure all three (3) fasteners holding the hood latch support bracket to the radiator support to 12 N-m (9 lb-ft) («Figure 2»).

7. Place a pair of channel lock pliers on the front side of the hood latch support bracket and force upward until the bracket is bent approximately 4 degrees (bend bottom of bracket forward). Do this by bending the bracket on both sides of the latch.

8. Check the hood closing effort by raising the hood 25 cm (10") and close to ensure that condition has been eliminated. If a hood closing effort still exists, repeat Step 7 until it has been eliminated.

9. Secure the fastener that attaches the pencil bracket to the bottom of the radiator support to 12 N-m (9 lb-ft) («Figure 1»).

OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage



DEALER CODING



OASIS CODES: 111000, 112000


Figure 1 - Article 00-21-2


Figure 2 - Article 00-21-2

01-7, Publication Date: MARCH 30, 2001



FORD:
1999 MUSTANG

ISSUE:
A "squeak" may be heard on some vehicles from the rear suspension when driving slowly over speed bumps. This may be caused by the outer sleeve of the lower control arm bushing rubbing on the outboard sub-frame ear.

ACTION:
Install spacer washer between the inner sleeve of the control arm bushing and the inboard sub-frame ear. Refer to the following Service Procedure for details.


SERVICE PROCEDURE

1. Raise vehicle on hoist and inspect both rear lower control arm bushings for signs of contact with the sub-frame ear («Figure 1»).

a. If signs of contact are evident, install Spacer Washers (XR3Z-5561-AA).

2. Remove both rear wheels.

3. Remove the bolts from both rear exhaust pipe support brackets. Press out the remaining four (4) exhaust pipe rubber hangers and let the rear part of the exhaust system hang.

4. Remove the nuts from both lower control arm bushing bolts and pull the bolts back about 25mm (1") (just far enough to provide clearance so that the washer can be installed). DO NOT remove bolts («Figure 2»).

5. Install spacer washers in front of the bushing as shown in «Figure 2».

NOTE:
NOTE: THE CONTROL ARM BUSHINGS MUST BE NEUTRALIZED BEFORE THEY ARE TIGHTENED.

6. Push bolts back in and install nuts. Do not tighten at this time.

7. Tack-weld the washer to the sub-frame ears to prevent it from turning and causing a squeak («Figure 3»).


NEUTRALIZING CONTROL ARM BUSHINGS

1. Place a tall screw-type jack stand at the front of vehicle under the front crossmember, just below the steering gear. Adjust the stand to make contact with the crossmember, but do not raise the vehicle («Figure 4»).

2. Place an automatic transmission jack or screw-type jack under the lower control arm and compress the arm as far as possible without raising the vehicle off the hoist («Figure 5»).

3. Torque the lower control arm bolt to 250 N-m (184 lb-ft).

4. Install wheels and road test vehicle to confirm the repair.



OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage



DEALER CODING



OASIS CODES: 304000, 702000, 702200


Figure 1 - Article 01-7-1


Figure 2 - Article 01-7-1


Figure 3 - Article 01-7-1


Figure 4 - Article 01-7-1


Figure 5 - Article 01-7-1


99-11, Publication Date: MAY 27, 1999
FORD:
1995-97 PROBE, THUNDERBIRD
1995-99 CONTOUR, CROWN VICTORIA, ESCORT, MUSTANG, TAURUS

LINCOLN-MERCURY:
1995-97 COUGAR
1995-98 MARK VIII
1995-99 CONTINENTAL, GRAND MARQUIS, MYSTIQUE, SABLE, TOWN CAR, TRACER
1999 COUGAR
2000 LS

LIGHT TRUCK:
1995-97 F SUPER DUTY, F-250 HD, F-350
1995-99 ECONOLINE, EXPLORER, F-150, F-250 LD, RANGER, VILLAGER, WINDSTAR
1997-99 EXPEDITION, MOUNTAINEER
1998-99 NAVIGATOR
1999 SUPER DUTY F SERIES

ISSUE:
This TSB article is being published as a comprehensive Noise, Vibration and Harshness (NVH) diagnostic procedure. This procedure will also be in 2000 model year and future Workshop Manuals in the NVH Section.

ACTION:
Utilize the flowchart diagrams to work a problem from SYMPTOM to SYSTEM to COMPONENT to CAUSE. The tools and techniques section is expanded to include ALL NVH diagnostic "tools". There are expanded SYMPTOM CHARTS to assist with problem resolution. A revised NVH course is available through regional training centers. The course is "NVH Principals and Diagnostics", course code # 30s03t0. This course utilizes the same techniques that are in the revised diagnostic procedure.

Refer to the

² Noise, Vibration and Harshness Work Shop Manual Section attached.

OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: INFORMATION ONLY

OASIS CODES: 497000, 597997, 701000, 702000, 703000

98-23, Publication Date: NOVEMBER 10, 1998


FORD:
1990-97 THUNDERBIRD
1990-99 MUSTANG, TAURUS SHO
1991-99 CROWN VICTORIA, ESCORT, TAURUS
1992-94 TEMPO
1993-97 PROBE
1995-99 CONTOUR

LINCOLN-MERCURY:
1990-97 COUGAR
1991-99 CONTINENTAL, GRAND MARQUIS, SABLE, TOWN CAR, TRACER
1992-94 TOPAZ
1993-98 MARK VIII
1995-99 MYSTIQUE

LIGHT TRUCK:
1990 BRONCO II
1990-97 AEROSTAR
1990-99 RANGER
1991-99 EXPLORER
1994-96 BRONCO
1994-97 F SUPER DUTY, F-250 HD
1994-99 ECONOLINE, F-150, F-250 LD, F-350
1995-99 WINDSTAR
1997-99 EXPEDITION, MOUNTAINEER
1998-99 NAVIGATOR
1999 F-250 HD, SUPER DUTY F SERIES

ISSUE:
This TSB article is a diagnostic procedure to address vehicles that exhibit lean driveability symptoms and may or may not have any Diagnostic Trouble Codes (DTCs) stored in memory.

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

l Lack of Power

l Spark Knock/Detonation

l Buck/Jerk

l Hesitation/Surge on Acceleration

l Malfunction Indicator Lamp (MIL) Illuminated - DTCs P0171, P0172, P0174, P0175 may be stored in memory


OBDII DTCs

l P0171, P0174 (Fuel system lean, Bank 1 or 2)

l P0172, P0175 (Fuel system rich, Bank 1 or 2)

l P1130, P1131, P1132, (HO2S11 lack of switching, Bank 1)

l P1150, P1151, P1152, (HO2S21 lack of switching, Bank 2)


OBDI DTCs

l 181, 189 (Fuel system lean, Bank 1 or 2)

l 179, 188 (Fuel system rich, Bank 1 or 2)

l 171, 172, 173 (HO2S11 lack of switching, Bank 1)

l 175, 176, 177 (HO2S21 lack of switching, Bank 2)

l 184, 185 (MAF higher/lower than expected)

l 186, 187 (Injector pulse width higher/lower than expected)

NOTE:
DO NOT DISCONNECT THE BATTERY. IT WILL ERASE KEEP ALIVE MEMORY AND RESET LONG TERM FUEL TRIM AND BARO TO THEIR STARTING/BASE VALUES. THE BARO PARAMETER IDENTIFICATION DISPLAY (PID) IS USED FOR THIS DIAGNOSTIC PROCEDURE. ALL OBDII APPLICATIONS HAVE THIS PID AVAILABLE. THERE ARE SOME OBDI VEHICLES THAT DO NOT HAVE THE BARO PID, FOR THESE VEHICLES OMIT THE BARO CHECK AND REFER ONLY TO STEPS 2, 3, AND 4 IN THE DIAGNOSTIC PROCEDURE.

1. Look at the BARO PID. Refer to the Barometric Pressure Reference Chart in this article. At sea level, BARO should read about 159 Hz (29.91 in. Hg). As a reference, Denver, Colorado at 1524 meters (5000 ft.) altitude should be about 144 Hz (24.88 in. Hg.). Normal learned BARO variability is up to ±6 Hz (±2 in. Hg.). If BARO indicates a higher altitude than you are at (7 or more Hz lower than expected), you may have MAF contamination. If available, Service Bay Diagnostic System (SBDS) has a Manifold Absolute Pressure (MAP) sensor that can be used as a barometric pressure reference. Use "MAP/BARO" test under "Powertrain," "Testers and Meters." Ignore the hookup screen. Connect GP2 to the reference MAP on the following screen.

NOTE:
REMEMBER THAT MOST WEATHER SERVICES REPORT A LOCAL BAROMETRIC PRESSURE THAT HAS BEEN CORRECTED TO SEA LEVEL. THE BARO PID, ON THE OTHER HAND, REPORTS THE ACTUAL BAROMETRIC PRESSURE FOR THE ALTITUDE THE VEHICLE IS BEING OPERATED IN. LOCAL WEATHER CONDITIONS (HIGH AND LOW PRESSURE AREAS) WILL CHANGE THE LOCAL BAROMETRIC PRESSURE BY SEVERAL INCHES OF MERCURY (±3 Hz, ±1 in. Hg.).

NOTE:
BARO IS UPDATED ONLY WHEN THE VEHICLE IS AT HIGH THROTTLE OPENINGS. THEREFORE, A VEHICLE WHICH IS DRIVEN DOWN FROM A HIGHER ALTITUDE MAY NOT HAVE HAD AN OPPORTUNITY TO UPDATE THE BARO VALUE IN KAM. IF YOU ARE NOT CONFIDENT THAT BARO HAS BEEN UPDATED, PERFORM THREE OR FOUR HEAVY, SUSTAINED ACCELERATIONS AT GREATER THAN HALF-THROTTLE TO ALLOW BARO TO UPDATE.



2. On a fully warmed up engine, look at Long Term Fuel Trim at idle, in Neutral, A/C off, (LONGFT1 and/or LONGFT2 PIDs). If it is more negative than -12%, the fuel system has learned lean corrections which may be due to the MAF sensor over-estimating air flow at idle. Note that both Banks 1 and 2 will exhibit negative corrections for 2-bank system. If only one bank of a 2-bank system has negative corrections, the MAF sensor is probably not contaminated.

3. On a fully warmed up engine, look at MAF voltage at idle, in Neutral, A/C off (MAF V PID). If it's 30% greater than the nominal MAF V voltage listed in the Powertrain Control/Emissions Diagnosis (PC/ED) Diagnostic Value Reference Charts for your vehicle, or greater than 1.1 volts as a rough guide, the MAF sensor is over-estimating air flow at idle.

4. If at least two of the previous three steps are true, proceed to disconnect the MAF sensor connector. This puts the vehicle into Failure Mode and Effects Management (FMEM). In FMEM mode, air flow is inferred by using rpm and throttle position instead of reading the MAF sensor. (In addition, the BARO value is reset to a base/unlearned value.) If the lean driveability symptoms go away, the MAF sensor is probably contaminated and should be replaced. If the lean driveability symptoms do not go away, go to the PC/ED Service Manual for the appropriate diagnostics.

NOTE:
DUE TO INCREASINGLY STRINGENT EMISSION/OBDII REQUIREMENTS, IT IS POSSIBLE FOR SOME VEHICLES WITH MAF SENSOR CONTAMINATION TO SET FUEL SYSTEM DTCs AND ILLUMINATE THE MIL WITH NO DRIVEABILITY CONCERNS. DISCONNECTING THE MAF ON THESE VEHICLES WILL, THEREFORE, PRODUCE NO IMPROVEMENTS IN DRIVEABILITY. IN THESE CASES, IF THE BARO, LONGFT1, LONGFT2, AND MAF V PIDs INDICATE THAT THE MAF IS CONTAMINATED, PROCEED TO REPLACE THE MAF SENSOR.

After replacing the MAF sensor, disconnect the vehicle battery (5 minutes, minimum) to reset KAM, or on newer vehicles, use the "KAM Reset" feature on the New Generation Star (NGS) Tester and verify that the lean driveability symptoms are gone.

OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: INFORMATION ONLY

OASIS CODES: 206000, 610000, 610500, 610600, 610700, 611000, 611500, 612000, 612500, 614000, 614500, 614600, 69829800-21, Publication Date: SEPTEMBER 29, 2000

FORD:
1994-2000 MUSTANG

ISSUE:
Some vehicles may exhibit a hood that is hard to close. This may be cause by a hood latch support bracket that is improperly adjusted.

ACTION:
Adjust the hood latch support bracket. Refer to the following Service Procedure for details.


SERVICE PROCEDURE

1. Loosen the bolt that attaches the pencil bracket to the bottom of the radiator support («Figure 1»).

2. Check to see if the hoodlatch is interfering with the striker (on inside of hood).

a. Gently push hood down after engaging secondary latch and see if the hood is forced sideways in either direction.

b. Inspect the hood latch to see if paint has been chipped off of either corner. This may help to determine if the hood latch is misadjusted.

3. If there is interference between the hood latch and striker, loosen the three (3) fasteners in the hood latch support bracket that attaches it to the radiator support (one on the top side and two on the forward side) («Figure 2»).

4. Move the hood latch support bracket approximately 2mm in the opposite direction of the interference and tighten the top fastener.

5. Perform Step 2 to see if the interference condition has been eliminated; if not, repeat Step 4 until the hood latch freely engages the striker.

6. Secure all three (3) fasteners holding the hood latch support bracket to the radiator support to 12 N-m (9 lb-ft) («Figure 2»).

7. Place a pair of channel lock pliers on the front side of the hood latch support bracket and force upward until the bracket is bent approximately 4 degrees (bend bottom of bracket forward). Do this by bending the bracket on both sides of the latch.

8. Check the hood closing effort by raising the hood 25 cm (10") and close to ensure that condition has been eliminated. If a hood closing effort still exists, repeat Step 7 until it has been eliminated.

9. Secure the fastener that attaches the pencil bracket to the bottom of the radiator support to 12 N-m (9 lb-ft) («Figure 1»).

OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage



DEALER CODING



OASIS CODES: 111000, 112000


Figure 1 - Article 00-21-2


Figure 2 - Article 00-21-2

01-7, Publication Date: MARCH 30, 2001



FORD:
1999 MUSTANG

ISSUE:
A "squeak" may be heard on some vehicles from the rear suspension when driving slowly over speed bumps. This may be caused by the outer sleeve of the lower control arm bushing rubbing on the outboard sub-frame ear.

ACTION:
Install spacer washer between the inner sleeve of the control arm bushing and the inboard sub-frame ear. Refer to the following Service Procedure for details.


SERVICE PROCEDURE

1. Raise vehicle on hoist and inspect both rear lower control arm bushings for signs of contact with the sub-frame ear («Figure 1»).

a. If signs of contact are evident, install Spacer Washers (XR3Z-5561-AA).

2. Remove both rear wheels.

3. Remove the bolts from both rear exhaust pipe support brackets. Press out the remaining four (4) exhaust pipe rubber hangers and let the rear part of the exhaust system hang.

4. Remove the nuts from both lower control arm bushing bolts and pull the bolts back about 25mm (1") (just far enough to provide clearance so that the washer can be installed). DO NOT remove bolts («Figure 2»).

5. Install spacer washers in front of the bushing as shown in «Figure 2».

NOTE:
NOTE: THE CONTROL ARM BUSHINGS MUST BE NEUTRALIZED BEFORE THEY ARE TIGHTENED.

6. Push bolts back in and install nuts. Do not tighten at this time.

7. Tack-weld the washer to the sub-frame ears to prevent it from turning and causing a squeak («Figure 3»).


NEUTRALIZING CONTROL ARM BUSHINGS

1. Place a tall screw-type jack stand at the front of vehicle under the front crossmember, just below the steering gear. Adjust the stand to make contact with the crossmember, but do not raise the vehicle («Figure 4»).

2. Place an automatic transmission jack or screw-type jack under the lower control arm and compress the arm as far as possible without raising the vehicle off the hoist («Figure 5»).

3. Torque the lower control arm bolt to 250 N-m (184 lb-ft).

4. Install wheels and road test vehicle to confirm the repair.



OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage



DEALER CODING



OASIS CODES: 304000, 702000, 702200


Figure 1 - Article 01-7-1


Figure 2 - Article 01-7-1


Figure 3 - Article 01-7-1


Figure 4 - Article 01-7-1


Figure 5 - Article 01-7-1


99-11, Publication Date: MAY 27, 1999
FORD:
1995-97 PROBE, THUNDERBIRD
1995-99 CONTOUR, CROWN VICTORIA, ESCORT, MUSTANG, TAURUS

LINCOLN-MERCURY:
1995-97 COUGAR
1995-98 MARK VIII
1995-99 CONTINENTAL, GRAND MARQUIS, MYSTIQUE, SABLE, TOWN CAR, TRACER
1999 COUGAR
2000 LS

LIGHT TRUCK:
1995-97 F SUPER DUTY, F-250 HD, F-350
1995-99 ECONOLINE, EXPLORER, F-150, F-250 LD, RANGER, VILLAGER, WINDSTAR
1997-99 EXPEDITION, MOUNTAINEER
1998-99 NAVIGATOR
1999 SUPER DUTY F SERIES

ISSUE:
This TSB article is being published as a comprehensive Noise, Vibration and Harshness (NVH) diagnostic procedure. This procedure will also be in 2000 model year and future Workshop Manuals in the NVH Section.

ACTION:
Utilize the flowchart diagrams to work a problem from SYMPTOM to SYSTEM to COMPONENT to CAUSE. The tools and techniques section is expanded to include ALL NVH diagnostic "tools". There are expanded SYMPTOM CHARTS to assist with problem resolution. A revised NVH course is available through regional training centers. The course is "NVH Principals and Diagnostics", course code # 30s03t0. This course utilizes the same techniques that are in the revised diagnostic procedure.

Refer to the

² Noise, Vibration and Harshness Work Shop Manual Section attached.

OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: INFORMATION ONLY

OASIS CODES: 497000, 597997, 701000, 702000, 703000

98-23, Publication Date: NOVEMBER 10, 1998


FORD:
1990-97 THUNDERBIRD
1990-99 MUSTANG, TAURUS SHO
1991-99 CROWN VICTORIA, ESCORT, TAURUS
1992-94 TEMPO
1993-97 PROBE
1995-99 CONTOUR

LINCOLN-MERCURY:
1990-97 COUGAR
1991-99 CONTINENTAL, GRAND MARQUIS, SABLE, TOWN CAR, TRACER
1992-94 TOPAZ
1993-98 MARK VIII
1995-99 MYSTIQUE

LIGHT TRUCK:
1990 BRONCO II
1990-97 AEROSTAR
1990-99 RANGER
1991-99 EXPLORER
1994-96 BRONCO
1994-97 F SUPER DUTY, F-250 HD
1994-99 ECONOLINE, F-150, F-250 LD, F-350
1995-99 WINDSTAR
1997-99 EXPEDITION, MOUNTAINEER
1998-99 NAVIGATOR
1999 F-250 HD, SUPER DUTY F SERIES

ISSUE:
This TSB article is a diagnostic procedure to address vehicles that exhibit lean driveability symptoms and may or may not have any Diagnostic Trouble Codes (DTCs) stored in memory.

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

l Lack of Power

l Spark Knock/Detonation

l Buck/Jerk

l Hesitation/Surge on Acceleration

l Malfunction Indicator Lamp (MIL) Illuminated - DTCs P0171, P0172, P0174, P0175 may be stored in memory


OBDII DTCs

l P0171, P0174 (Fuel system lean, Bank 1 or 2)

l P0172, P0175 (Fuel system rich, Bank 1 or 2)

l P1130, P1131, P1132, (HO2S11 lack of switching, Bank 1)

l P1150, P1151, P1152, (HO2S21 lack of switching, Bank 2)


OBDI DTCs

l 181, 189 (Fuel system lean, Bank 1 or 2)

l 179, 188 (Fuel system rich, Bank 1 or 2)

l 171, 172, 173 (HO2S11 lack of switching, Bank 1)

l 175, 176, 177 (HO2S21 lack of switching, Bank 2)

l 184, 185 (MAF higher/lower than expected)

l 186, 187 (Injector pulse width higher/lower than expected)

NOTE:
DO NOT DISCONNECT THE BATTERY. IT WILL ERASE KEEP ALIVE MEMORY AND RESET LONG TERM FUEL TRIM AND BARO TO THEIR STARTING/BASE VALUES. THE BARO PARAMETER IDENTIFICATION DISPLAY (PID) IS USED FOR THIS DIAGNOSTIC PROCEDURE. ALL OBDII APPLICATIONS HAVE THIS PID AVAILABLE. THERE ARE SOME OBDI VEHICLES THAT DO NOT HAVE THE BARO PID, FOR THESE VEHICLES OMIT THE BARO CHECK AND REFER ONLY TO STEPS 2, 3, AND 4 IN THE DIAGNOSTIC PROCEDURE.

1. Look at the BARO PID. Refer to the Barometric Pressure Reference Chart in this article. At sea level, BARO should read about 159 Hz (29.91 in. Hg). As a reference, Denver, Colorado at 1524 meters (5000 ft.) altitude should be about 144 Hz (24.88 in. Hg.). Normal learned BARO variability is up to ±6 Hz (±2 in. Hg.). If BARO indicates a higher altitude than you are at (7 or more Hz lower than expected), you may have MAF contamination. If available, Service Bay Diagnostic System (SBDS) has a Manifold Absolute Pressure (MAP) sensor that can be used as a barometric pressure reference. Use "MAP/BARO" test under "Powertrain," "Testers and Meters." Ignore the hookup screen. Connect GP2 to the reference MAP on the following screen.

NOTE:
REMEMBER THAT MOST WEATHER SERVICES REPORT A LOCAL BAROMETRIC PRESSURE THAT HAS BEEN CORRECTED TO SEA LEVEL. THE BARO PID, ON THE OTHER HAND, REPORTS THE ACTUAL BAROMETRIC PRESSURE FOR THE ALTITUDE THE VEHICLE IS BEING OPERATED IN. LOCAL WEATHER CONDITIONS (HIGH AND LOW PRESSURE AREAS) WILL CHANGE THE LOCAL BAROMETRIC PRESSURE BY SEVERAL INCHES OF MERCURY (±3 Hz, ±1 in. Hg.).

NOTE:
BARO IS UPDATED ONLY WHEN THE VEHICLE IS AT HIGH THROTTLE OPENINGS. THEREFORE, A VEHICLE WHICH IS DRIVEN DOWN FROM A HIGHER ALTITUDE MAY NOT HAVE HAD AN OPPORTUNITY TO UPDATE THE BARO VALUE IN KAM. IF YOU ARE NOT CONFIDENT THAT BARO HAS BEEN UPDATED, PERFORM THREE OR FOUR HEAVY, SUSTAINED ACCELERATIONS AT GREATER THAN HALF-THROTTLE TO ALLOW BARO TO UPDATE.



2. On a fully warmed up engine, look at Long Term Fuel Trim at idle, in Neutral, A/C off, (LONGFT1 and/or LONGFT2 PIDs). If it is more negative than -12%, the fuel system has learned lean corrections which may be due to the MAF sensor over-estimating air flow at idle. Note that both Banks 1 and 2 will exhibit negative corrections for 2-bank system. If only one bank of a 2-bank system has negative corrections, the MAF sensor is probably not contaminated.

3. On a fully warmed up engine, look at MAF voltage at idle, in Neutral, A/C off (MAF V PID). If it's 30% greater than the nominal MAF V voltage listed in the Powertrain Control/Emissions Diagnosis (PC/ED) Diagnostic Value Reference Charts for your vehicle, or greater than 1.1 volts as a rough guide, the MAF sensor is over-estimating air flow at idle.

4. If at least two of the previous three steps are true, proceed to disconnect the MAF sensor connector. This puts the vehicle into Failure Mode and Effects Management (FMEM). In FMEM mode, air flow is inferred by using rpm and throttle position instead of reading the MAF sensor. (In addition, the BARO value is reset to a base/unlearned value.) If the lean driveability symptoms go away, the MAF sensor is probably contaminated and should be replaced. If the lean driveability symptoms do not go away, go to the PC/ED Service Manual for the appropriate diagnostics.

NOTE:
DUE TO INCREASINGLY STRINGENT EMISSION/OBDII REQUIREMENTS, IT IS POSSIBLE FOR SOME VEHICLES WITH MAF SENSOR CONTAMINATION TO SET FUEL SYSTEM DTCs AND ILLUMINATE THE MIL WITH NO DRIVEABILITY CONCERNS. DISCONNECTING THE MAF ON THESE VEHICLES WILL, THEREFORE, PRODUCE NO IMPROVEMENTS IN DRIVEABILITY. IN THESE CASES, IF THE BARO, LONGFT1, LONGFT2, AND MAF V PIDs INDICATE THAT THE MAF IS CONTAMINATED, PROCEED TO REPLACE THE MAF SENSOR.

After replacing the MAF sensor, disconnect the vehicle battery (5 minutes, minimum) to reset KAM, or on newer vehicles, use the "KAM Reset" feature on the New Generation Star (NGS) Tester and verify that the lean driveability symptoms are gone.

OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: INFORMATION ONLY

OASIS CODES: 206000, 610000, 610500, 610600, 610700, 611000, 611500, 612000, 612500, 614000, 614500, 614600, 698298

BubbaFett
 
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