I had to have the valves replaced for #3 cylinder. They got overheated and stetched. I was told this was a result of towing my 22' trailer. It has a max loaded rate of 5900lbs (it isn't ever near that). My truck is rated to tow 6600lbs. I was told that the temps in the combustion chamber got high enough to overheat the valves even though there wasn't any change in temp gauge. Has anyone else had this problem? My truck doesn't even have 170000kms on it. I do live in a quite mountainous area.

 

I have never in my life heard of valves stretching. If you are still under warranty, then this just sounds like an excuse to not honor the warranty.

If you are out of warranty then it sounds like someone is just making up a story to try to explain why it is not Fords fault that your "valves stretched".

Sounds more like burnt valves. Most likely the head came from the factory without enough cam to rocker roller clearance with the lash adjuster collapsed.

I have heard some crazy explanations from service managers, a person who probably doesn't know what the part he is talking about looks like.

Valves stretching Thats a good one. Are they made of play-dough?

 

I am not an expert on this, but I would think if you got the engine hot enough to heat steel to the point it would stretch, an aluminum head the valves were in would melt. (These engines do have aluminum heads, don't they?)
I may be wrong but, sounds like BS to me.

 

There just trying to duck the warranty. Big time BS from the service department.

 

Regardless, if you are within your factory tow specs, they do not have a leg to stand on. I would ask if this was a heat issue then why was it linited to #3.
I suspect the valves in #3 were not heat treated properly and fell out of the manufactuer process. It's a defect no matter how you slice it.

 

This is on a 98 f-150. It is not under warrenty. The job was done by a private shop. They did farm out the machining work. The valves were stretched enough that I didn't have any compression in that cylinder. The shop that did the work I Have known the head mechanic for 26 yrs. The explination came from the machinist. He also said that he had seen a few like this. He also said that he has not had any come back after he has fiwed them. I kind of think (agree) that they were inferior valves. Thanks guys.

 

on the 04'+ models The 4.6L Engines are Iron Heads...the 4.2L and 5.4L are Aluminum.

I just realized and read the guy is talkin about a 98' wrong forum section for that.

 

Opps sorry new user and didn't look close enough at where I was.

 

Have them take a close look at the Baro reading on their scan tool, the mass airflow sensors are known to go bad and report a higher altitude then it actually is to the engine module, high altitude = lean fuel mixture = detonation, valve problems, too high combustion temps, nothing good comes out of to lean of a mixture.

 

Thats may be so but I doubt detonation due to the knock sensor, and the O2 sensor will try and keep it at 14.7:1 fuel mixture. So a major lean condition will really not happen, it may not get actually to 14.7, and run a little rough but it will not lean out enough to cuase a catastrophic failure.
Massairflow sensor only helps in the fine tune to acquire the actual 14.7:1. BTW a bad massairflow sensor will turn on the check engine light and return a code of P0100 to P0104.

 

...Moved ....

 

Our shop has seen a few of them with maf sensors causing lean condition, one of them detonated the tops off some of the pistons (towing a camper) The others had lean codes but no maf codes because it hadn't failed it was just out of calibration, Here is a bulliten from fomoco about it,



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1998 Ford Truck F 150 4WD Pickup V8-4.6L SOHC VIN W
Vehicle Level Powertrain Management Technical Service Bulletins All Technical Service Bulletins Engine - Lean Driveability Symptoms


Engine - Lean Driveability Symptoms
Notes

Article No.
98-23-10

11/23/98

MASS AIR FLOW (MAF) - SENSOR
CONTAMINATION - SERVICE TIP

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

^ 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)

NOTE O 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 not 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 tow 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









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