Question about Mercury Grand Marquis
What is the fuel pressure reading? it should be 42-46 pounds, these are mostly lean engine fuel mixture codes, so get the fuel pressure tested, there is a test port on the top of the engine in the fuel supply rail to the fuel injectors., also have the exhaust checked for excessive back pressure, u have EGR codes as well. I am a retired Ford master technician in electronic engine control repair, if u want to call me at ho,me that is cool with me, 925-459-0571
Posted on Jun 17, 2010
Here can find information about this OBD fault codes...
DTC P1405 - Differential Pressure Feedback Sensor Upstream Hose Off Or Plugged
If it is throwing a Service Engine light, then it is something electronic. A bad EGR valve would not turn on the Service Engine light by itself. The DPFE sensor would. If it is on the way out, that would make the light intermittent. Mine ran for months before throwing a steady light (2000 5.4 V8). Is it idling rough at low RPM as well? If so, my advice is the following - look at the DPFE sensor to see if there is any noticible damage where the harness connects (mine was melted off). It is a real simple fix to replace the DPFE sensor - about $65 at the parts store and 15 minutes of time. I also did my EGR valve while I was in there - that won't hurt but may not be necessary (about $70). For a quick easy "tune up", open up the throttle body and give a good cleaning with carb cleaner and old toothbrush. It will run rough for a few seconds, give it some gas and that should clean out all the carbon real good. Don't forget to disconnect the neg. battery first and cycle the key thru a few times to reset the sensors before changing the DPFE.
DTC P1131 - Lack Of Heated Oxygen Sensor Bank 1 Sensor 1 Switches - Sensor Indicates Lean
DTC P0171 - System Too Lean Bank 1
This TSB article is being republished in its entirety to update the Service Procedure:
The Malfunction Indicator Lamp (MIL) may illuminate and Diagnostic Trouble Codes (DTCs) P0133, P0171 and/or P1131 may be stored in memory. Additionally, there may be one or more of the following driveability symptoms:
Near stall or stall at idle
Detonation on acceleration
This may be caused by cold condensate from the A/C system dripping onto the Heated Exhaust Gas Oxygen (HEGO) sensor causing thermocycling of the HEGO sensor .
Divert water from dripping onto the sensor by installing a fabricated drain tube to the end of the A/C drain. This should reroute the water and reduce the possibility of the above conditions occurring. Refer to the following Service Procedure for details.
Fabricate a drain tube from PCV Vent Tube (F85Z-6758-BA). To create the drain tube extension, remove the rubber cylinder from the plastic tube and discard. Cut the plastic tube..
Remove the transmission fluid level indicator.
Remove the right front wheel.
Remove the right front fender well splash guard.
Clean the area around the transmission filler tube and then remove the tube. Be sure to cover the hole using duct tape (or equivalent) to prevent contaminants from entering the transmission.
Replace the right front HEGO Sensor (F88Z-9F472-AB) and leave the connector disconnected.
Modify the PCV vent tube (Figure 1) to make a drain for the A/C condensate drain.
Using needle nose pliers or equivalent, stretch the drain tube elbow fitting for ease of installation.
Refer to Figure 1 and fabricate a tool using a 61x2.5 cm (24x1") I.D. pipe as shown.
Lubricate the elbow with water.
NOTE: DO NOT USE SILICONE TO LUBRICATE THE ELBOW AS IT WILL FALL OFF.
Using the tool, install the modified drain tube at the 7:00 position toward the frame (Figure 2).
Clean the transmission filler tube.
NOTE: BE CAREFUL NOT TO DAMAGE THE O-RING AS THIS COULD CREATE LEAKS OR ALLOW CONTAMINATION INTO THE TRANSMISSION.
Lightly lubricate the transmission filler tube O-ring with petroleum jelly and reinstall the tube into the transmission.
Torque the bolt to 11-14 N-m (8-10 lb-ft).
NOTE: MAKE SURE THE BODY SIDE HEGO WIRING CONNECTOR IS IN THE LOCATOR HOLE IN THE BACK OF THE HEAD.
Connect the right front HEGO sensor connector.
Start the vehicle and verify water flow direction. Make sure no condensation drips onto the exhaust manifold bolt.
Reinstall the right front splash guard.
Reinstall the right front wheel.
Clean and reinstall the transmission fluid level indicator.
NOTE: DEALERS MUST ALSO PERFORM TSB 97-26-19 TO REPROGRAM THE POWERTRAIN CONTROL MODULE (PCM).
PART NUMBER PART NAME
F85Z-6758-BA PCV Vent Tube
F88Z-9F472-AB Heated Exhaust Gas Oxygen (HEGO) Sensor
DTC P1130 - Lack Of Heated Oxygen Sensor Bank 1 Sensor 1 Switches - Fuel Trim At Limit
DTC P1150 - Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Fuel Trim At Limit
DTC P1151 - Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean
Try to look for the TSB(Technical Service Bulletin)...
DTCs P1131, P1151, P1132 AND P1152: UPSTREAM HO2S(S) NOT SWITCHING. DTCs P1130 AND P1150: FUEL SYSTEM NOT SWITCHING AT FUEL TRIM (RICH OR LEAN)
Diagnostic Trouble Codes (DTCs) P1131 bank 1 (Cylinder 1) and P1151 bank 2 indicate the fuel/air ratio is correcting rich for an overly lean condition. The HO2S voltage is less than 0.45 volt. DTCs P1132 bank 1 (Cylinder 1) and P1152 bank 2 indicate the fuel/air ratio is correcting lean for an overly rich condition. The HO2S voltage is greater than 0.45 volt.
DTCs P1130 and P1150 indicate the fuel control system has reached maximum compensation for a lean or rich condition and the HO2S is not switching.
DTC/HO2S Reference List
HO2S-11 = DTCs P1131, P1132 and P1130
HO2S-21 = DTCs P1151, P1152 and P1150
Excessive fuel pressure.
Leaking fuel injector(s).
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Contaminated fuel injector(s)
Air leaks after the MAF.
Vacuum leaks (vacuum lines and gaskets).
Restricted air inlet.
Fuel purge system.
Improperly seated engine oil dipstick.
Stuck open EGR valve.
Exhaust leaks before or near the HO2Ss.
Check intake air system for leaks, obstructions and damage.
Check air cleaner element, air cleaner housing for blockage.
Verify integrity of the PCV system.
Check for vacuum leaks.
Posted on Jun 17, 2010
Here is what i came up with after some searching:
It does appear that the CEL codes pertain to either air, heated air or air pressure)
Garnered from Auto Repair Forums at www.jonko.com... Sticky please?
MASS AIR FLOW (MAF) - SENSOR
CONTAMINATION - SERVICE TIP
1990-99 MUSTANG, TAURUS SHO
1991-99 CROWN VICTORIA, ESCORT, TAURUS
1991-99 CONTINENTAL, GRAND MARQUIS, SABLE, TOWN CAR, TRACER
1993-98 MARK VIII
1990 BRONCO II
1994-97 F SUPER DUTY, F-250 HD
1994-99 ECONOLINE, F-150, F-250 LD, F-350
1997-99 EXPEDITION, MOUNTAINEER
1999 F-250 HD, SUPER DUTY F SERIES
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.
Follow the diagnostic procedures described in the following Service Tip. The revised diagnostic procedure is a more accurate means of diagnosing the symptoms.
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.
^ Lack of Power
^ Spark Knock/Detonation
^ Hesitation/Surge on Acceleration
^ Malfunction Indicator Lamp (MIL) Illuminated -
DTCs P0171, P0172, P0174, P0175 may be stored in memory
^ 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)
^ 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: 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 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.
for more info, hit this one: http://www.modularfords.com/forums/showthread.php/103142-97-Mercury-Grand-Maquis-CEL
Posted on Jun 17, 2010
Wait!! here is a tutorial video that may knock out some of those codes. I have used this method twice on my car and worked fabulousy! removing the check engine light and added Horse Power
Check it out!
Posted on Oct 25, 2015
I have a 1996 ford f150 4.9 liter.The truck runs great but bad gas mileage.the only problem is i am getting codes p0401and p0402 what should i do.
Posted on Dec 18, 2009
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