Gasoline Engine Vacuum Specifications and Testing (diagnosing)

Use the directions and read the safety warnings that came with your vacuum gauge.

    When testing, connect vacuum gauge to a vacuum port on intake manifold. You want the reading to come after the throttle plate. If you do not have to drive the vehicle, the brake booster vacuum hose is a good place to tap in. As you will get good volume. It is important not to drive the vehicle with a gauge tied into brake booster vacuum hose.

Engine Vacuum Specifications

  • Engine cranking, not starting: 2″ – 5″
  • Engine running at idle, warm: 18″ – 21″
  • Wide open throttle: 0″ – 3″
  • Engine deceleration: 21″ – 24″
  • Engine Vacuum – How to Test
    Snap throttle Jumps to 2″ then on decel moves to 25″ Healthy
    Snap throttle Jumps to 1″ then on decel moves to 22″ Fair but worn
    Idle 8″ or less Vacuum leak, loose intake manifold
    Idle Fluctuated between 14″ – 19″ Worn valve guides or head gasket blown between 2 cylinders
    Idle Reading drops from normal Burnt valve, valve stuck open, misfiring spark plug
    Idle 8″ – 14″ Valve timing incorrect or large camshaft overlap
    Idle 14″ – 16″ Ignition timing wrong
    Idle Moves between 12″ – 16″ Idle mixture incorrect
    Slow engine speed rise Needle falls then rises suddenly Blocked exhaustWeak valve springs
    3000 rpm Needle fluctuates and worsens with higher rpm Weak valve springs

    2006 BMW M6 Misfire V10 – Faulty Ignition coil – Stuck in Cylinder Head

    This 2006 BMW M6 V10 came in rough running with a misfire. The misfire was easily located and diagnosed, but trouble arose when the coil at cylinder 10 broke. The top electrical connector portion snapped off when the mechanic was attempting to remove it from the engine.

    This tech note is more about how to I got the coil out verse the usual diagnostic study.

    The tech attempted to extract the coil using needle nose hose pliers, but it would not budge. The rubber boot was stuck to the spark plug and it was slowly falling apart with each attempt at removal.

    To remove the coil, we drilled a hole in the center of the coil top.

    Then we screwed in a 3 mm sheet metal screw with a washer.

    Next, using the nub on the valve cover, we levered the coil out using a prybar. Now be careful when you get to this point. The coil is brittle and you will only get one shot at it.
    levering coil out

    You can see here how dry the boot was and the brown residue inside inside.
    dry boot

    Be sure when installing the new coil to apply a small amount of dielectric grease to the boot to prevent this from happening in the future.

    2003 Hyundai Santa Fe 2.4 Evap Leak, Fuel tank pressure sensor fault P0451



    The evaporative emission control system prevents hydrocarbon vapors from escaping from the fuel tank into the atmosphere where they could form photochemical smog. Gasoline vapors are collected in the charcoal canister. The Fuel Tank Pressure Sensor (FTP) is an integral part of the evaporative monitoring system. The PCM monitors the FTPS signal to detect vacuum decay and excess vacuum. The FTP sensor measures the difference between the air pressure inside the fuel tank and outside air pressure to check the purge control solenoid valve operation and for leak detection in the evaporative emission control system by monitoring pressure and vacuum levels in the fuel tank during the purge control solenoid valve operating cycles.


    If the oscillation of fuel tank pressure’s signal is out of the threshold value, the PCM determines that a fault exists and a DTC is stored.

    When I arrived the vehicle ECM memory had been cleared and no fault codes were present.
    2003 Hyundai Santa Fe P0451

    The FTP data PID was reading -0.3 inHg.
    2003 Hyundai Santa Fe P0451

    I opened fuel filler cap. Doing so should neutralize the FTP reading and the PID should display the equivalency of atmospheric pressure. With the cap off, the reading remained at -0.3 inHg. This told me there could have been a blockage or a short.

    I raised vehicle and located FTP sensor. It was behind rear of fuel tank. I back-probed the 3 wire connector and using the factory wiring diagram to determine voltages recorded my readings.
    Before I go over my readings, let’s review the wiring and note what to expect.

    Pin 1: Sensor reference voltage – 5 volts
    Pin 2: Sensor ground – Must be lower than 0.5 volts, expect around 0.1.
    Pin 3: Sensor signal – between 0.5 – 4.5 volts, fluctuates in relation to fuel tank pressure.
    2003 Hyundai Santa Fe P0451 FTP wiring

    My results:
    Pin 1: Sensor reference voltage – 5 volts
    2003 Hyundai Santa Fe P0451

    Pin 2: Sensor ground – 0.01.
    2003 Hyundai Santa Fe P0451

    Pin 3: Sensor signal – 1.9 volts.
    2003 Hyundai Santa Fe P0451

    The FTP sensor was reading a steady voltage as the scan tool data stream displayed. Next I gained access to the engine control module (ECM) and back-probed FTP sensor wire.
    2003 Hyundai Santa Fe P0451

    Seeing the sensor reading was the same, I found a 5 volt source voltage and jumped it to the FTP sensor pin on the ECM. Voltage remained at 1.9 volts. This told me the wire was shorted. Next I cut the FTP sensor signal wire into the ECM.

    The FTP data PID was now reading -1.5 inHg.
    2003 Hyundai Santa Fe P0451

    Next I jumped 5 volts to the FTP sensor wire at the ECM side I cut earlier. The scan tool now read 1.4 in Hg:
    2003 Hyundai Santa Fe P0451

    This told me there was in fact a short in the FTP sensor wire. I ran a new wire and the problem was fixed.

    I generally do not hunt down the faulty wire as it is quicker to run a new wire.

    2005 Nissan Sentra 2.5l Idle Surge – Erratic Idle

    The following vehicle had an idle surge from 1500 – 1800 RPM. A new throttle housing was installed to remedy the problem. After the part replacelent, the idle surge became worse.

    When the engine is started the idle surges up and down.

    No fault codes were stored.

    When replacing the throttle housing (throttle body) you have to perform an Idle Air Volume Relearn. It is important to follow directions very carefully. If the relearn does not work the first attempt, try again. It has taken me a few relearns in the past to push it through.

    Before performing Idle Air Volume Learning, make sure that all of the following conditions are met. Idle Air Volume Learning will fail if any of the following targets are missed for even a moment.

  • Battery voltage: More than 12.9 V (At idle)
  • Engine coolant temperature: 70 – 95 °C (158 – 203 °F)
  • PNP switch: ON
  • Electric load switch: OFF (Air conditioner, headlamp, rear window defogger)
  • Steering wheel straight-ahead position
  • Vehicle stationary
  • Transmission oil warmed-up
  • The following video highlights the idle air volume learning procedure using an advanced scan tool with Nissan factory options. When performing the throttle body adaption portion of the procedure, you will hear the throttle body open and close. If this does not occur, the procedure has failed. Attmept again or correct problem prohibiting relearn.

    If idle air volume learning cannot be performed successfully, check the following items:

  • Throttle valve is fully closed.
  • PCV valve operation.
  • Check that downstream of throttle valve is free from air leakage.
  • When the above items check OK, there may be a defective part prohibiting relearn. Run your diagnostic strategy.

    If the following conditions occur after engine has started, eliminate cause of condition and perform Idle air volume learning again:

  • Engine stalling
  • Errattic idle
  • 2005 BMW 325 P0171 P0174 227 228 Fault Codes Dinan Stage 2

    The BMW had fault codes 227 and 228 stored (P0171, P0174) indicating a lean fuel system. This means the vehicle is running lean and the DME has tried to correct the condition but has reached it upper limit. Fault codes 227 and 228 are specific to a fault when the engine is at part throttle (not idle). This tells us that it’s unlikely the lean condition caused by and engine vaccum leak.


    First I ran engine until it reached operating temperature. Then monitored fuel trim at idle using my scan tool. As you can see the Idle Load fuel trim is normal.

    Next I went for a drive in the vehicle. I ran the engine through each RPM range from idle, steady cruise to WOT (wide open throttle). You can see the Part Load fuel trim is indicating a lean condition, (by adding fuel) during my entire test drive. Part Load does take some time to update, so I suggest a 15 minute test drive at the minimum.
    During my test drive I am able to eliminate many possible causes of the lean condition. For example; I monitor Idle Load fuel trim at idle to see if it could be a vaccum leak. That coupled with freeze frame data ruleda vacuum leak out.
    I also perform a WOT test on the fuel system. If the oxygen sensor holds above 800 mv for the entire time I am at WOT, the fuel pump and fuel delivery system can deliver enough fuel. Next I check the engine and exhaust system by looking at G/PS or Kg/H. This reading tells me about engine efficiency. I can estimate the amount of air at a given RPM, therefore testing the MAF sensor without touching it.

    The 325 had Dinan performance software and an airbox, or what they refer to as Stage 2. I was convinced the problem was with the Dinan components but I have only an hour to prove this to be correct.

    The airbox in modified by introducing a cold air intake, removing a baffle and changing the filter from a panel to a version of a cone style.

    Here’s what I did.

    I found the area where the baffle was removed (Dotted White Line) and temporarily mounted a piece of plastic in place.

    I plugged the cold air intake port with a plastic cap.

    Next I reprogrammed the car back to the factory DME software.

    I went for a test drive, repeated the same RPM ranges as my previous one. The Part Load fule trim began to drop into an acceptable range.

    Next I contacted Dinan with the information. They agreed to write a custom DME map for this car. Once I received the map I programmed the car again with Dinan’s MIP tool. It took a week or so to receive the new DME map, so the vehicle owner had to drive with the MIL light ON.

    Once programmed I test drove the vehicle aagin, within the same RPM ranges. You can see part load came back down to a normal range and the vehicle is no longer exhibiting a lean condition.

    This is a tricky fix. Without my standard fuel trim drive cycle test (to test components during the test drive), I may have replaced parts that were not faulty. It is important to approach each and every fuel trim fault the same way. A structured test plan will build confidence and make quick work of these common faults.

    EMISSIONS WARRANTIES for US Cars ad Trucks from 1995

    Below is the US FEderal Government Emission Warranty Information

    United States Air and Radiation EPA420-F-96-020
    Environmental Protection March 1996

    Office of Mobile Sources
    EPA Environmental Fact Sheet


    Federally required emission control warranties protect you, the
    vehicle owner, from the cost of repairs for certain emission related
    failures that result from manufacturer defects in materials and
    workmanship or that cause your vehicle to exceed federal emission
    standards. Manufacturers have been required by federal law to provide
    emission control coverage for vehicles since 1972. There are two
    federal emission control warranties discussed in this fact sheet: (A)
    “Performance Warranty” and (B) “Design and Defect Warranty”. This
    fact sheet explains each warranty in detail, provides you with a list
    of some of the parts covered under these warranties, explains the
    procedures for making an emissions warranty claim, and answers some of
    the most commonly asked questions about emissions warranties.
    Finally, we will give you some tips on how to prevent future
    emission-related failures and maintain the longevity of your vehicle’s


    The Performance Warranty covers repairs which are required during
    the first 2 years or 24,000 miles of vehicle use because the vehicle
    failed an emission test. Specified major emission control components
    are covered for the first 8 years or 80,000 miles. If you are a
    resident of an area with an Inspection and Maintenance (I/M) program
    that meets federal guidelines, you are eligible for this warranty
    protection provided that:

    * Your car or light-duty truck fails an approved emissions test;

    * Your vehicle is less than 2 years old and has less than 24,000
    miles (up to 8 years/80,000 miles for certain components); and

    * Your state or local government requires that you repair the
    vehicle; and

    * The test failure does not result from misuse of the vehicle or a
    failure to follow the manufacturers’ written maintenance
    instructions; and

    * You present the vehicle to a warranty-authorized manufacturer
    representative, along with evidence of the emission test failure,
    during the warranty period.

    During the first 2 years/24,000 miles, the Performance Warranty
    covers any repair or adjustment which is necessary to make your
    vehicle pass an approved, locally-required emission test and as long
    as your vehicle has not exceeded the warranty time or mileage
    limitations and has been properly maintained according to the
    manufacturer’s specifications.


    The Design and Defect Warranty covers repair of emission related
    parts which become defective during the warranty period. The Design
    and Defect warranty for model year 1995 and newer light-duty cars and
    trucks is outlined below:

    Design and Defect Warranty Coverage for 1995 and newer light-duty

    * Emission control and emission related parts are covered for the
    first 2 years or 24,000 miles of vehicle use; and

    * Specified major emission control components are covered for the
    first 8 years or 80,000 miles of vehicle use.

    According to federal law, an emission control or emission related
    part, or a specified major emission control component, that fails
    because of a defect in materials or workmanship, must be repaired or
    replaced by the vehicle manufacturer free of charge as long as the
    vehicle has not exceeded the warranty time or mileage limitations for
    the failed part.

    Design and Defect Warranty coverage may vary depending on the
    type of vehicle you have (e.g., heavy-duty trucks, motorcycles or
    recreational vehicles have different time and mileage requirements).
    To determine the length of warranty coverage that applies to your
    vehicle, look for the emissions warranty information in your owner’s
    manual or warranty booklet. If you own a California vehicle, you may
    be entitled to additional warranty coverage.

    The owner’s manual or warranty booklet will also provide you with
    guidance on the procedures for obtaining warranty coverage. If you
    have questions about the emissions warranties on your vehicle or need
    help in filing a warranty claim, contact your local car dealer or the
    manufacturer’s zone or regional representative listed in your owner’s
    manual or warranty booklet.

    What Emission Control and Emission Related Parts Are Covered by The
    Design and Defect Warranty?

    An emission control part is any part installed with the primary
    purpose of controlling emissions. An emission related part is any
    part that has an effect on emissions. Listed below are some examples
    of parts or systems which fall under these definitions. A more
    complete list can be found in your owner’s manual/warranty booklet.
    If any of the parts listed below fail to function or function
    improperly because of a defect in materials or workmanship, causing
    your vehicle to exceed federal emission standards, they should be
    repaired or replaced under the emissions warranty if your vehicle is
    less than 2 years old and has been driven less than 24,000 miles. One
    manufacturer may use more parts than another, so the following list is
    not complete for all vehicles.


    Exhaust Gas Conversion Systems

    oxygen sensor thermal reactor
    catalytic converter dual-walled exhaust pipe

    Exhaust Gas Recirculation System

    EGR valve thermal vacuum switch
    EGR solenoid EGR spacer plate
    EGR backpressure transducer Sensor and switches use to
    control EGR flow

    Evaporative Emission Control System

    purge valve fuel filler cap
    purge solenoid vapor storage canister and filter

    Positive Crankcase Ventilation (PCV) System

    PCV valve PCV solenoid

    Air Injection System

    Air pump diverter, bypass, or gulp valve
    reed valve anti-backfire or deceleration valve

    Early Fuel Evaporative (EFE) System

    EFE valve thermal vacuum switch
    heat riser valve

    Fuel Metering System

    electronic control module (unit) or EFI air flow meter, computer
    command module or mixture control unit, deceleration controls,
    electronic choke, fuel injectors, fuel injection units and fuel
    altitude compensator sensor, bars or rails for EFI or TBI systems,
    mixture settings on sealed fuel mixture control solenoid, diaphragm
    or other systems, fuel metering components that achieve closed/other
    feedback control sensors/loop operation switches and valves

    Air Induction System

    thermostatically controlled air cleaner, air box

    Ignition Systems

    electronic spark advance timing advance/retard systems,
    high energy electronic ignition

    Miscellaneous Parts

    hoses, gaskets, brackets, clamps and other accessories used in the
    above systems


    These are examples of other parts of your vehicle which have a
    primary purpose other than emissions control but which nevertheless
    have significant effects on your vehicle’s emissions. If any of these
    parts fail to function or function improperly, your vehicle’s
    emissions may exceed federal standards. Therefore, when any of the
    parts of the following systems are defective in materials or
    workmanship and have failed in a way that would be likely to cause
    your vehicle’s emissions to exceed federal standards, they should be
    repaired or replaced under the emissions warranty:

    Fuel Injection System

    fuel distributor

    Air Induction System

    turbocharger intake manifold

    Exhaust System

    exhaust manifold

    Ignition System

    distributor spark plugs
    ignition wires and coil

    Miscellaneous Parts

    hoses, gaskets, brackets, clamps, and other accessories used in
    the above systems.

    What Are Specified Major Emission Control Components?

    There are three specified major emission control components,
    covered for the first 8 years or 80,000 miles of vehicle use on 1995
    and newer vehicles:

    * Catalytic converters.

    * The electronic emissions control unit or computer (ECU).

    * The onboard emissions diagnostic device or computer (OBD).

    Catalytic converters are critical emission control components
    that have been installed on most cars and trucks manufactured since
    1975. Since engines don’t burn fuel completely during the combustion
    process, the exhaust contains a significant amount of harmful
    pollutants such as carbon monoxide, hydrocarbons, and oxides of
    nitrogen. The catalytic converter aids the conversion of these
    pollutants to less harmful substances such as carbon dioxide, water
    vapor, nitrogen, and oxygen before the exhaust is expelled into the

    The electronic emissions control unit or computer monitors
    certain powertrain functions and controls various operating parameters
    to help the vehicle run efficiently and with the lowest possible
    emissions. Ignition, transmission function, air injection, exhaust
    gas recirculation (EGR), engine operating temperature and fuel system
    parameters are some of the systems monitored and/or controlled by the
    electronic emissions control unit.

    The onboard emissions diagnostic device monitors the operation of
    a vehicle’s emission control system and alerts the driver with a
    dashboard light when malfunctions occur. The system will record where
    the problem is occurring and assist automotive technicians in
    diagnosing and repairing emission control malfunctions. Since some
    emission control malfunctions do not have an adverse effect on vehicle
    performance, they can go undetected by the driver for quite some time.
    The onboard diagnostic device will help catch malfunctions early,
    preventing a significant output of harmful exhaust emissions from your
    vehicle, and possibly in time to be covered by the emissions control
    warranty. Often this “device” is part of the electronic control unit
    mentioned above.

    In the future, there may be other parts or components that
    qualify for this coverage. Check your owner’s manual or warranty book
    for possible additional coverage.

    How Long Do the Emissions Warranties Apply to Individual Parts of My

    For 1995 and newer model year vehicles, emission control and
    emission related parts are warranted for the first 2 years or 24,000
    miles of vehicle use. Specified major emission-control components are
    warranted for the first 8 years or 80,000 miles of vehicle use.

    Parts with a stated replacement interval, such as, “replace at
    15,000 miles or 12 months,” are warranted up to the first replacement
    point only.

    How Do I Know Whether I Am Entitled to Coverage Under the Emissions

    If you or a qualified automotive technician can show that an
    emission control or emission related component, or a specified major,
    emission-control component, is defective, the repair or replacement of
    the part is probably covered under the Design and Defect warranty. If
    your vehicle failed a federally approved emissions test and has not
    exceeded the time and mileage limitations for the Performance
    warranty, any repairs or adjustments necessary for your vehicle to
    pass should be covered by the manufacturer if the failure was not
    caused by improper maintenance or abuse. When you believe you have
    identified a defective part, or your vehicle fails an emission test,
    you should follow the procedures for making a warranty claim as
    identified by the manufacturer in your owner’s manual or warranty
    booklet. When taking your vehicle in to have repairs performed under
    the Performance Warranty, be sure to have with you a copy of the I/M
    test report as proof of your emissions test failure.

    May I Have My Regular Repair Facility Perform Warranty Repairs?

    If you plan to have the manufacturer pay for a repair under
    either of the emissions warranties, you must take the vehicle to a
    facility authorized by the vehicle manufacturer for repair to give
    them the opportunity to diagnose and repair it. Note that if your
    regular repair facility is not authorized by the vehicle manufacturer,
    they are not obligated to advise you of parts that are covered under
    warranty. Before giving your automotive technician the “go ahead” to
    perform repairs, check your owner’s manual/warranty booklet for
    possible warranty coverage.

    Do the Emissions Warranties Apply to Used Vehicles?

    Yes. It does not matter if you bought your vehicle new or used
    from a dealer or anyone else. As long as the vehicle has not exceeded
    the warranty time or mileage limitations, these warranties apply.

    IMPORTANT NOTE: Before buying a used vehicle, be sure that all of
    the emission control components as originally installed by the
    manufacturer are present and functioning properly. If emission
    control components are missing or have been tampered with, or the
    configuration of the exhaust system has been changed, the emissions
    warranties on this vehicle may be void. In addition, if you live in
    an area with an I/M program, the vehicle will probably not pass
    inspection and you will incur the expense of parts or repairs
    necessary for the vehicle to pass.

    Can Any Portion of An Emissions Warranty Repair Be Charged to Me?

    If you have valid warranty claim, you cannot be charged for any
    costs associated with the diagnosis or repair of the problem,
    including labor charges, parts, or miscellaneous items that are
    necessary to complete the repair. For example, if a manufacturer
    agrees to replace a catalytic converter under the emissions warranty,
    you should not be charged for the diagnosis of the bad converter, or
    any pipes, brackets, adjustments, or labor needed to complete the

    What Reasons Can the Manufacturer Use to Deny a Warranty Claim?

    If your vehicle is within the age and mileage limits for the
    applicable emissions warranty, the manufacturer can only deny coverage
    if evidence shows that you have failed to properly maintain and use
    your vehicle, causing the part or emission test failure. Some
    examples of misuse and malmaintenance include the following:

    * vehicle abuse such as off-road driving or overloading; or

    * tampering with emission control parts or systems, including
    removal or intentional damage of such parts or systems; or

    * improper maintenance, including failure to follow maintenance
    schedules and instructions specified by manufacturer, or use of
    replacement parts which are not equivalent to the originally
    installed parts.

    What Should I Do If My First Attempt to Obtain Warranty Coverage Is

    If your first attempt to receive emissions warranty coverage is
    denied, you should do the following:

    1) Ask for a detailed explanation, in writing as to why emissions
    warranty coverage was denied; and

    2) Ask for the name(s) of the person(s) involved in the decision
    to deny coverage, including anyone from the manufacturer’s
    regional or zone office; and

    3) Ask for the name(s) of the person(s) with the manufacturer you
    should contact to appeal the denial of coverage under the
    emissions warranty.

    4) Contact and, if necessary, write to the person mentioned above
    requesting coverage and giving the basis for your request. Repeat
    and continue the appeal process until you are satisfied or have
    exhausted all means of appeal.

    What If the Dealer Claims That My Vehicle Can Pass the I/M Test
    Without Repair?

    The law does not require that you fail every I/M test in order to
    trigger the warranty. If a valid test shows that you have an emission
    problem or there is a defective part, you should get it fixed, while
    your vehicle is still within the warranty period. Otherwise, you
    might fail a future test because of the same problem and have to pay
    for the repair yourself. If you doubt your original test results or
    the dealer’s results or diagnosis, you can always get another opinion
    from another dealer or your I/M program.

    How Can Maintenance Affect My Emission Warranty Coverage?

    Performance and the cost of scheduled maintenance are your
    responsibility. You may either perform scheduled maintenance yourself
    or have a qualified repair facility perform it for you.

    If a part fails as a direct result of your vehicle not being
    properly maintained or being used in a manner inconsistent with the
    manufacturer’s recommendations, or a part fails as a result of the
    vehicle being involved in an accident, the manufacturer may not be
    required to repair or replace the failed part under warranty. For
    example, failure to replace the spark plugs at the intervals specified
    in the maintenance schedule can lead to misfiring and eventual damage
    to your catalytic converter – a very expensive part to replace. If
    the maintenance is not performed properly as recommended, the
    manufacturer may deny warranty coverage.

    To ensure maximum air pollution reduction from the emission
    control system, as well as to ensure continued warranty coverage,
    better gas mileage and performance, and longer vehicle life, you
    should have all maintenance performed as recommended by the
    manufacturer’s schedule. A list of scheduled maintenance for your
    vehicle can be found in the owner’s manual or warranty booklet.

    Do I Have to Show Any Maintenance Receipts Before I Can Make an
    Emissions Warranty Claim?

    No. Proof of maintenance is not required in order to obtain
    coverage under the emissions warranty if an emission control or
    emission related component, or a specified major emission control
    component, is found to be defective in materials or workmanship.
    However, when it is likely that the lack of proper maintenance has
    caused the particular part to fail, you may be asked to show that
    scheduled maintenance was performed.

    If you perform scheduled maintenance yourself, you should keep a
    detailed log of work performed and any receipts for parts purchased to
    perform the maintenance. In some instances, you may be asked to
    qualify your ability to perform such maintenance. Vehicles should
    always be maintained according to manufacturers’ specifications.

    Are Dealers the Only Persons Allowed to Perform Scheduled Maintenance
    Recommended by the Manufacturer?

    No. Scheduled maintenance may be performed by anyone who has the
    knowledge and ability to perform the maintenance and repair. You may
    even maintain the vehicle yourself, as long as the maintenance is
    performed according to the manufacturer’s instructions provided with
    the vehicle.

    For your protection, before taking your vehicle to a repair
    facility to have any maintenance performed, check your maintenance
    booklet and make a list of the scheduled maintenance to be performed
    at that time. We suggest that you present this list to your auto
    technician as opposed to merely asking for a “tune-up” or a “12,000
    miles servicing.” Your receipt should list all the maintenance
    performed and should be kept for your records.

    If you maintain the vehicle yourself, you should keep receipts
    for parts and a maintenance log to verify your work.

    If I Need Replacement Parts, Must I Use the Vehicle Manufacturer’s
    Parts Only?

    No. A manufacturer cannot require the use of any specific brand
    of parts in the maintenance of your vehicle. However, the
    manufacturer can require you to use parts that are of equal quality to
    the original parts.

    If I Buy a Used Vehicle, How Do I Know Whether It Has Been Maintained
    According to The Maintenance Schedule?

    The best way to learn whether the vehicle has been maintained
    according to its schedule is to ask the seller for receipts proving
    that all of the scheduled maintenance was performed. Having the
    receipts on hand will provide necessary evidence if the question of
    maintenance arises when considering repairs under warranty. To
    prevent any loss of your vehicle’s emission performance, you should
    continue to follow the maintenance schedule in the owner’s manual or
    warranty booklet.

    If the seller does not have the owner’s manual, warranty booklet
    or maintenance schedule, you can obtain them from the manufacturer.

    How Will I Know If My Claim Has Been Accepted As Valid?

    After you present your vehicle for a Performance Warranty claim,
    the manufacturer has 30 days to either repair the vehicle or notify
    you in writing that the claim has been denied. If you are making a
    Performance Warranty claim and your I/M program imposes a shorter
    repair deadline, the manufacturer must meet the deadline. Because of
    the significance of these deadlines, you should get written
    verification from the dealer showing that they acknowledge the date by
    which repairs must be made.

    There are no specific requirements for Defect Warranty claims,
    however, manufacturer responses should be made within a reasonable
    time period.

    What Happens If the Manufacturer Does Not Respond to My Performance
    Warranty Claim Within the 30-Day Deadline?

    You may agree to extend the deadline, or it will be automatically
    extended if the delay was beyond the control of the manufacturer.
    Otherwise, a missed deadline means the manufacturer forfeits the right
    to deny the claim. You may then have the repair performed at a
    facility of your choice, at the manufacturer’s expense. (This
    requirement only applies to Performance Warranty claims.)

    What Do I Do If the Manufacturer Will Not Honor What I Believe to Be a
    Valid Emissions Warranty Claim?

    If you believe the manufacturer has not honored a valid claim and
    your vehicle has not exceeded the time and mileage limitations, you
    should contact an authorized warranty representative and follow the
    procedures outlined in your owner’s manual or warranty booklet. If the
    authorized dealer denies your warranty claim, contact the
    manufacturer’s regional or zone office for further assistance. If you
    are still not satisfied, follow the appeals procedure outlined in your
    manual or warranty booklet.

    Of course, you are entitled to pursue any independent legal
    actions you consider appropriate to obtain coverage under the
    emissions warranties. In addition, the Environmental Protection
    Agency (EPA) is authorized to investigate the failure of manufacturers
    to comply with the terms of these warranties. If you have followed
    the manufacturer’s procedures (including those for appeals) for making
    a warranty claim as set out in your owner’s manual or warranty
    booklet, have received a written denial and you are not satisfied with
    the manufacturer’s determination, you may submit a letter to EPA at
    the following address. It should provide details of the situation
    including the basis for the claim, a copy of the written denial,
    copies of your letters to the manufacturers, and copies of any
    receipts for emission control parts and repairs you have paid for:

    U.S. Environmental Protection Agency
    Vehicle Programs & Compliance Division (6405J)
    Attn: Warranty Complaints
    401 M Street, SW
    Washington, DC 20460

    Other sources of assistance may be your local or State consumer
    protection agency or office of the Attorney General. You also should
    be aware that low-cost or free legal assistance may be available
    through a local legal aid office, the State bar association, or a law
    school clinic staffed by law students.

    In Summary

    If an emission control or emission related part, or a specified
    major emission control component is defective, or if your vehicle
    fails an I/M test, and your vehicle is within the time and mileage
    limitations for emissions warranty coverage:

    * Present a warranty claim to an authorized warranty representative.

    If your warranty claim is denied:

    * Ask for the reason for denial, in writing.

    * Follow the appeal procedures in your owner’s manual.

    If you are not satisfied with the manufacturer’s decision:

    * Contact the EPA, which will investigate the denial of a
    valid emissions warranty complaint.

    Keep This With Your Vehicle for Future Reference.

    BMW E39 M5 Dual Mass Air Flow MAF Testing Specifications

    Use the following information as an aide when testing BMW E39 dual MAF sensors. Keep in mind, a problem with mechanical engine components can affect MAF readings and besure you have a solid base engine before condeming parts.

    KOEO (Key On – Engine OFF)taken at sensor back probing with DVOM
    B1 AFM 1.02 Volts
    B2 AFM 1.02 Volts
    Using scan toolBoth AFM sensors read 0.9 Volt on GT1 under maf data stream.

    Hot, engine running at idle taken at sensor back probing with DVOM
    B1 AFM 1.30 Volts
    B2 AFM 1.29 Volts
    Using scan toolBoth AFM sensors read 1.0 Volt on GT1 under maf data stream.

    2500 RPM taken at sensor back probing with DVOM
    B1 AFM 1.85 Volts
    B2 AFM 1.75 Volts
    Using scan toolBoth AFM sensors read 1.5 Volt on GT1 under AFM data stream


    IAT sensor not used on bank 2 AFM. However sensors are interchangeable.

    Testing using a labscope. In Park or
    Neutral, parking brake on.
    Snap throttle to reach max voltage output.
    (scope pattern shows a dual trace of both
    The sensors should be within 0.1 volts of each other.