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Thread: 96 Accord EX automatic running too rich :(

  1. #1

    Unhappy 96 Accord EX automatic running too rich :(

    Hi there....I just bought a 1996 Accord EX 4 cylinder automatic with 175k miles. They CEL came on so I swung by the auto parts store and had them read the code (p0172) which apparently is the code for running too rich in bank 1. After several hours searching google, I read that the code might be several things. First I changed the MAP sensor, disconnected the battery to clear the code....but it came back after driving around 100 miles. Then I changed the upper (pre CAT) O2 sensor...was insanely difficult to remove...I had to have a mechanic remove it and replace with the part that I brought and he cleared the code. The CEL returned just before I could change the spark plugs, and remained after I changed them. The car starts right up with no problems, but it idles kinda rough and it has no power going uphill....I desperately need some advice!

  2. #2

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    Try running some fuel injector cleaner through it. Rich running could be due to a fuel injector(s) not seating and leaking into one or more cylinders. You may also find that one or more fuel injectors are bad, though this would require more extensive testing. If you do find out you need injectors, there is a place in South Carolina that sells them cheaper new than parts stores charge for re-man and the ones I got for a Plymouth minivan worked perfectly.

  3. #3

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    I will give that a shot when I get off work, but I have been reading something about perhaps changing the fuel pressure regulator....has anyone had any experience with this? The inspection goes out this month and while it passes the emissions check...it will never pass with the check engine light on. I just moved to NJ from TX...the inspections are ridiculously strick

  4. #4

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    I suppose Lucas makes the best fuel system cleaner?

  5. #5

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    Lucas is one of the best if not the best. Sadly my problem wasn't even the injectors themselves but water I picked up with a tank from a good station. The water just wouldn't get out of the injectors even though the fuel rail was clear and I dropped the tank and cleaned it out.

  6. #6

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    ive had great succes with seafoam it worked really good to clear my injecters had prolbem with dribbling injecters and hard to start in the morning now it works great no rich runing othere then the other problems im have in a prevuse thread

  7. #7

    Unhappy PLEASE HELP

    welp...I don't think that the injector cleaner helped with my problems. Does anyone have any advice as to what my next step should be?....should I replace the fuel pressure regulator? I am at a loss and my inspection expires today...I really need to pass inspection...is it possible to clear the code with a scanner long enough to pass the inspection? (they hook up their own scanner to check) will it show that the code was cleared on thier scan?...I still intend to chase down the cause of the problem, but I need to be able to legally drive to work and back....PLEASE HELP

  8. #8

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    Quote Originally Posted by merverferker View Post
    welp...I don't think that the injector cleaner helped with my problems. Does anyone have any advice as to what my next step should be?....should I replace the fuel pressure regulator? I am at a loss and my inspection expires today...I really need to pass inspection...is it possible to clear the code with a scanner long enough to pass the inspection? (they hook up their own scanner to check) will it show that the code was cleared on thier scan?...I still intend to chase down the cause of the problem, but I need to be able to legally drive to work and back....PLEASE HELP
    you can unplug the battery for a minute that should do the trick for the code but note if it does it again it will store a code so do it less then a mile from the smog shop butt no gerinty also check the main fuel relay these are known hondas to fail map senser tps and othere stuff very unlikely to fail mainly the main relay have you tryed to google main relay for 96 accord runing rich it might be some kinda vacum leak not to shure about that how is your idle in park low normle high jump around what does that do cuz that prolbem that causon that can be the cause of runing rich but thats just my $0.02 cents$ good luck

  9. #9

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    has any heard from dude yet
    {have fun}victems 93 honda civic hatch back. 95 trans am(tranny broke). 89 accord 5speed. 2000 civic si. 1999 civic d16y8

  10. #10

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    ummm....still not fixed...and it won't pass inspection after clearing the CEL because they hook it to a scanner and get a 'not ready' code....and I don't find much in the way of googling 'main relay' applying to my symptoms, but I will keep looking.....

  11. #11

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    would the O2 sensor after the CAT cause these types of problems?....I plan on changing it later anyway, but I do need to remedy this problem quickly (and cheap as possible)

  12. #12

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    the o2 thats a possible its hard to tell it could be the ecu highly unlikely your going to nead pro help do sorry butt thats what it looks like
    {have fun}victems 93 honda civic hatch back. 95 trans am(tranny broke). 89 accord 5speed. 2000 civic si. 1999 civic d16y8

  13. #13

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    found this on the net
    Auto Repair EncyclopediaHow To - Helpful Hints
    Brakes
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    Repairs and ServicesAir Pump Check Valve Replacement
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    Catalytic Converter Replacement
    Check Engine Light Diagnosis
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    Engine Computer (ECM/PCM) Replacement
    Engine Coolant Temperature Sensor (ECT) Replacement
    Exhaust Gas Recirculation Valve Replacement
    Exhaust Manifold Replacement
    Exhaust Pipe Replacement
    Exhaust Tail Pipe Replacement
    Front Oxygen Sensor Replacement
    Knock Sensor Replacement
    MAP Sensor Replacement
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    Rear Oxygen Sensor Replacement
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    Throttle Position SensorOBD II Code P0172 and P0175Facebook Twitter |
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    Fuel System Too Rich (Bank 1 or 2)
    Our emissions expert has put together the following information about the P0172 and P0175 fault code. We have also included diagnostic procedures you can take to your repair shop if the mechanic is having difficulty analyzing the code.

    Related Information
    Check Engine Light
    Diagnostic Assistant
    Emission Gas Definitions
    Intake Manifold Gasket
    Mass Airflow Sensor
    Fuel Filter Replacement
    Fuel Pump Replacement
    OBD II Fault Code

    OBD II P0172
    OBD II P0175
    Fault Code Definition

    OBD II P0172 Fuel System Too Rich (Bank 1)
    OBD II P0175 Fuel System Too Rich (Bank 2)
    Symptoms

    Check Engine Light will illuminate
    In some cases, no adverse conditions may be noticed by the driver
    In other cases, there may be performance problems, such as a lack of power on acceleration and some "coughing" or misfiring. The vehicle may have trouble idling, especially when warm or when sitting at a stoplight.
    Other codes may be set, such as P0300 (random, multiple misfires)
    Common Problems That Trigger the P0172 and P0175 Code


    PCM software needs to be updated

    Mass Airflow Sensor (MAF)
    Defective Manifold Absolute Pressure Sensor (MAP)
    Engine mechanical problems
    Defective Oxygen Sensor
    Defective Fuel Pressure Regulator
    Defective Coolant and/or Air Temperature Sensor
    Thermostat is stuck open

    Ignition Misfires
    Defective Throttle Position Sensor
    Defective or restricted fuel return line
    Defective Fuel Injectors
    Common Misdiagnoses

    Oxygen Sensors
    Fuel Pump
    Fuel Injectors
    Fuel Pressure Regulator
    Polluting Gases Expelled

    HCs (Hydrocarbons): Unburned droplets of raw fuel that smell, affect breathing, and contribute to smog
    CO (Carbon Monoxide): Partially burned fuel that is an odorless and deadly poisonous gas

    The Basics
    Combustion engines operate by burning an air/fuel mixture of about 14.7 to 1—14.7 parts air to 1 part fuel. When the air ratio goes below 14.7 parts, this is called a "rich" mixture. If the air rises above 14.7 parts, it is called a "lean" mixture.

    Rich Mixture = Too much fuel, not enough air
    Lean Mixture = Too much air, not enough fuel

    To keep the engine running properly, the Engine Control Module measures the oxygen content in the exhaust with oxygen sensors and makes adjustments to the mixture by injecting more or less fuel.

    The control module operates within specific parameters and under normal conditions, it will make minor adjustments to the air/fuel mixture. When these adjustments become too large, a fault code is set. When the P0172/P0175 code sets, the oxygen sensors are detecting too little oxygen in the exhaust and the control module is removing the maximum amount of fuel in its effort to maintain the proper air/fuel mixture.

    P0172/P0175 Diagnostic Theory for Shops and Technicians
    When a vehicle has the fault code P0172 and or P0175, it means that computer can no longer automatically adjust the mixture between air and fuel. Code P0172 applies to Bank 1 and P0175 applies to Bank 2. Code P0175 mainly applies to V6 or V8 engines because 4-cylinder engines generally have only one bank, though there are a few exceptions. Some of the high performance 4-cylinder and straight 6-cylinder engines (such as those in BMW and Lexus) split the cylinders into groups of two or three and call them separate banks.

    When the code says that the Fuel System is "too rich," it means that the computer has been subtracting more and more fuel, which is called Long Term Fuel Trim. Ideally, the Long Term Fuel Trim should be close to 1 to 2 percent. When a code P0172 is set, it means that the Fuel Trim is anywhere from -15 percent to as low as -30 percent compensated. When this happens, the computer knows that there is an improper condition in the control of the Fuel System.

    The first step in the diagnosis of a code P0172 and/or P0175 is to look at a minimum of three ranges of the Long Term Fuel Trim numbers on a scanner. Check the idle reading—3000 RPM unloaded and 3000 RPM with at least 50 percent load. Then check the freeze frame information for the code to see which range(s) failed and what the operating conditions were.

    Before we get into the main causes of P0172, let's explore why this code matters.

    Why Does a P0172/P0175 Code and Running "Too Rich" Matter?
    "Rich" running cars and trucks are highly polluting vehicles. CO pollution, which is poisonous and helps create ozone, is caused by vehicles that are running too rich. A rich condition can also cause misfires from "overfueling" (too much fuel for the Ignition Spark to burn), which puts raw fuel (HCs) into the atmosphere. When inhaled, these raw fuel droplets are very poisonous to living beings and contribute to the yellow/brown color in a polluted sky. When you are driving behind a "rich" running car or truck, it can smell very bad, somewhat like rotten eggs, and make you feel dizzy. This is caused by the Catalytic Converter consuming too much sulfur (part of vehicle fuel). However, it should be noted that a "rich" running engine can also have little or no smell, since CO itself is odorless.

    P0172 is not an Oxygen Sensor problem. Before a P0172 code is possible, the computer first ran a series of tests to validate the readings from the oxygen sensors. Since the oxygen sensors passed their readiness tests and didn't set any codes, the computer then looked to the Fuel Trim adjustment. When the computer determined the air-to-fuel mixture to be too rich, it then set the P0172 code.

    What Are Some Common Causes of Code P0172/P0175?
    Always check to make sure that there is not a PCM software update due or available. Often, as the vehicle's engine wears, the PCM's Fuel Map software inaccurately compensates for this condition. The fuel mixture grows rich and eventually, the code sets.

    An "over reporting" Mass Air Flow Sensor can be a common cause of a code P0172 and P0175. Essentially, this means that the Air Flow Sensor is telling the computer that much more air is entering the engine than actually is. Based on this large amount of air entering the engine, the engine computer or PCM sprays more fuel into the combustion chambers.

    Since the oxygen sensors are telling the computer that less fuel is needed, this causes confusion in the computer because the Mass Air Flow Sensor is still saying there is too much air and the Oxygen Sensor is reporting that the mixture is still too rich. The computer tried to compensate, but since resolution is impossible, it sets the code. It is important to restate that the Oxygen Sensors are accurate—the fuel mixture is too rich. In this case, the Air Flow Meter or Sensor is inaccurately reporting the real amount of air entering the engine.

    How Do I Know if the Problem Is the Mass Air Flow Sensor?
    There is a very effective "truth test" for any Mass Air Flow Sensor. Start the engine, let it idle, and then check the Barometric Pressure reading on the scan tool data. If the reading is about 34.5 Hg and you are close to sea level, you know that you have a defective Air Flow Meter because it is telling you that you are at about 4000 feet below sea level. (These conversion tables will help.) When the Mass Air Flow Sensor sees this Barometric reading, it adjusts its Air Density table and then "over reports" the actual amount of air entering the engine. It does this because the Barometric Pressure Sensor is actually part of the Mass Air Flow Sensor.

    Sometimes the Air Flow Sensor and the sensing wire get covered with dirt, dust, or oil residue, which can also set a P0172. Cleaning the sensor might hold off problems for a while, but eventually, the MAF sensor should be replaced. Always make sure the Air Filter and its enclosure are dirt-, dust-, and oil-free. If you clean and replace the filter and its enclosure as needed, you will prevent the new MAF from failing.

    Additional Causes of Code P0172/P0175

    Defective Manifold Absolute Pressure (MAP) Sensor and/or its vacuum line. Check the MAP reading and then do a manual vacuum reading. An engine needs to have at least 17 to 18 inches of vacuum in order to run properly. When the MAP reading is low, the PCM thinks that the vehicle is under heavy load and increases the fuel supply.
    Mechanical engine problems will cause a low MAP sensor reading because engine vacuum is low or erratic. A slipped or inaccurately installed Timing Chain or Timing Belt and/or leaking Head Gasket can cause poor vacuum and MAP readings. If the engine has a mechanical misfire from valve train problems or weak cylinder compression, it will send puffs of oxygen into the exhaust system. This will cause the Oxygen Sensors to receive false "lean" readings (high exhaust oxygen content).
    A defective Oxygen Sensor can sometimes cause a P0172. If the Oxygen Sensor heater element only works intermittently—well enough to pass the readiness test, but fails once the car has been driven for a while—the vehicle will go into "open loop."
    A stuck Fuel Pressure Regulator can cause a rich condition since the Fuel Pressure will be too high, causing an "over fueling" condition. Be sure to verify proper Fuel Pressure under various driving conditions.
    An inaccurate Coolant Temperature or Air Temperature Sensor can cause a rich condition because they will report that the engine is still cold, which will cause the PCM to keep the mixture rich long after the engine is at proper operating temperature.
    A Thermostat stuck in the open position can mechanically cause a code P0172, especially in cold climates. The engine won't warm up, preventing it from going into "closed loop" fuel control.
    Ignition misfires, like mechanical misfires, cause puffs of oxygen to keep hitting the Oxygen Sensors. Since the sensors will think the mixture is running lean, the PCM will add fuel to the mixture.
    A worn or stuck wiper in the Throttle Position Sensor will tell the PCM that more power is being requested by the operator. The PCM will add fuel to accommodate this false TPS reading.
    If the vehicle is not hoisted properly, the fuel return line can be pinched, causing a high Fuel Pressure condition. Always verify Fuel Pressure for any code P0172.
    Shorted Fuel Injector windings can cause the injectors to spray too much fuel, causing a rich condition. Be sure to verify the Pulse Width (the PCM "on" time) with the Labscope Injector Firing pattern. Be sure to "Ohm check" the injector winding resistance as well in order to verify that it's within specification.
    {have fun}victems 93 honda civic hatch back. 95 trans am(tranny broke). 89 accord 5speed. 2000 civic si. 1999 civic d16y8

  14. #14

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    another this might be better
    P0172 OBD-II Trouble Code
    Technical DescriptionSystem Too Rich (Bank 1)

    What does that mean?Basically this means that an oxygen sensor in bank 1 detected a rich condition (too little oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.

    Note: This DTC is very similar to P0175, and in fact your vehicle may show both codes at the same time.

    SymptomsYou will more than likely not notice any drivability problems, although there may be symptoms such as a misfire.

    CausesA code P0172 may mean that one or more of the following has happened:

    The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
    There could be a vacuum leak.
    There could be a fuel pressure or delivery problem
    Possible SolutionsPossible solutions include:

    Inspect all vacuum and PCV hoses, replace if necessary
    Cleanthe MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
    Inspect fuel lines for cracks, leaks, or pinches
    Check the fuel pressure at the fuel rail
    Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced.
    Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)

    Related P0172 Forum Topics
    {have fun}victems 93 honda civic hatch back. 95 trans am(tranny broke). 89 accord 5speed. 2000 civic si. 1999 civic d16y8

  15. #15

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    if not then you will need pro help
    {have fun}victems 93 honda civic hatch back. 95 trans am(tranny broke). 89 accord 5speed. 2000 civic si. 1999 civic d16y8

  16. #16

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    if you have face book look up a guy named eric the car guy
    {have fun}victems 93 honda civic hatch back. 95 trans am(tranny broke). 89 accord 5speed. 2000 civic si. 1999 civic d16y8

  17. #17

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    whew...that was a sizable amount of information....thanks...I ordered a Haynes repair manual and I will be looking into this later this week...I will update with any solutions that I find

  18. #18

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    so what was the problem
    {have fun}victems 93 honda civic hatch back. 95 trans am(tranny broke). 89 accord 5speed. 2000 civic si. 1999 civic d16y8

  19. #19

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    well I put on a new fuel pressure regulator and snapped the freaking bolt in the fuel rail....I removed the fuel rail lastnight as well as the fuel injectors...they are filthy. I will be cleaning them later today and I am trying to remove the broken bolt from the fuel rail.....oh and I will probably replace the fuel filter as well, but I want to make sure that I don't have any leaks at the regulator before I mess with the filter

  20. #20

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    as for as doing a leak test i just turn the kye and it would be a good idea to replace the fuel filter since your doing all of that thats my 2 cents good luck
    {have fun}victems 93 honda civic hatch back. 95 trans am(tranny broke). 89 accord 5speed. 2000 civic si. 1999 civic d16y8

  21. #21

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    after an hour of frustration, I removed the broken bolt from the fuel rail I cleaned the fuel rail and injectors and while I was in the neighborhood, I cleaned the EGR ports....I slapped everything back in and it seems to be running better....I didn't have much time to test drive it, but it was fine going to work this morning...it seemed to have more "go" than it did, and it hasn't bogged down like before (flooding because it was too rich?) anyway....I believe that I will drive it around today after work and tomorrow to see if it throws a CEL for anything

  22. #22

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    is working better
    {have fun}victems 93 honda civic hatch back. 95 trans am(tranny broke). 89 accord 5speed. 2000 civic si. 1999 civic d16y8

  23. #23

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    no it is not running better.....the CEL is back on....i assume for the same code because it is behaving in the same manner as it did before....lack of power, smelly exhaust, and rough idle....i dunno what to do...i guess i will take it to the shop and see if they can figure something out without breaking me

  24. #24

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    have you checked the egr ports and passeges the egr might be bad you should try the seafoam it worked for me there really aint much more to do then take out the main relay and check it for cracks burnd spots i dont think its that though
    {have fun}victems 93 honda civic hatch back. 95 trans am(tranny broke). 89 accord 5speed. 2000 civic si. 1999 civic d16y8

  25. #25

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    any luck
    {have fun}victems 93 honda civic hatch back. 95 trans am(tranny broke). 89 accord 5speed. 2000 civic si. 1999 civic d16y8

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