Hot answers tagged

9

There is no such thing as detectable "reversion" airflow to a MAF. Especially on a non turbocharged car. The MAF has no clue about the direction of flow, only how much energy it takes to keep the wire or film heated. I doubt that the "negative" aspect of your graph is ever seen. Even at idle, you shoud see 2-5 g/s. I wonder why the graph is kg/h... that ...


9

MAP = Manifold absolute pressure and is a sensor to measure vacuum, the computer calculates the engine air flow based on the vacuum, throttle position, and intake air temperature. The computer also measures the barometric pressure using the MAP sensor before the engine cranks, this lets the computer compensate for altitude, or how dense the air is. Typical ...


4

I wouldn't if there are no obvious defects in the housing. Sometimes parts stores will only sell items as the complete package. When buying a thermostat from oreilly's auto parts for my forenza the only thing they would sell me is the whole housing unit with the thermostat. When searching on ebay, I found the thermostat without needing to buy the housing as ...


3

Moves.. answer is a good one but you asked about advantages/disadvantages of MAF sensors. Disadvantages are: the sensor sits in the intake and thus restricts airflow. Airflow restrictions translate to performance restriction, particularly with vane style air flow meters. A simple example of this is the comparison between a Subaru STI MAF sensor and a ...


3

This is the calculation you're looking for. IMAP = RPM * MAP / IAT MAF = (IMAP/120)(VE/100)(ED)*(MM)/(R) Where manifold absolute pressure (MAP) is in kPa, intake air temp (IAT) is in degrees Kelvin, R is 8.314 J/°K/mole and the average molecular mass of air (MM) is 28.97 g/mole. Note that, in the above formula, the volumetric efficiency of the (4-cycle!) ...


3

Also, remember that MAF is a reading of the amount of air entering the engine. If you have a backflow issues (high backpressure) or even a timing issue where the valves are not opening and closing at the correct time (slack chains, jumped timing), your MAF sensor readings will reflect this as well. I know this post is late, but any who are looking into this ...


2

I just had these exact symptoms with a 2002 Vauxhall Astra. As well as the Crankshaft Sensor error (and the garage confirmed it had previously thrown out an O2 sensor error). Mine was the EGR valve, with fuels that use a lot of additives (here in the UK that's 'supermarket fuel') the valve quickly becomes caked in carbon. The EGR (exhaust gas ...


2

Checking a list of TSBs for this set of codes, this looks like a promising candidate: 01-028/04 MAZDA SPECIAL PROGRAM (MSP05) - 2004 MAZDA3 - O2 SENSOR DTC ERROR, P2195 / P2196 From what you describe, a problematic O2 sensor could easily lead to the idling, sputtering and smells that you describe. If the sensor is stuck reading full lean, it's highly ...


2

When discussing the Throttle Position Sensor You understand it's function electrically on a 5v reference. If you were to take the sensor off and look at the side that goes against the throttle body then you would notice the coil. The inductive loop works as follows. When the butterfly of the throttle body opens (up until wide open throttle) voltage ...


2

Do you have a source for that formula? Is it possible that you are reading Calculated engine load value, which would indeed be zero when you are in neutral? Range: 0 to 100 Units: % Formula: A*100/255 I did find this page which defines it as: Calculated Load Value -- Indicates a percentage of peak available torque. Reaches 100% at wide open ...


2

I think you misunderstand the purpose of the Mass Air Flow (MAF) sensor (and whoever wrote what you read doesn't understand, as well). The purpose of the MAF is to read the amount of incoming air. As the incoming air flows over the heated sensor, it cools the sensor which regulates the amount of electricity which can flow through it. It is in no way ...


2

It should be on or near the air cleaner assembly. It looks like a square thing with a 60 pin connector on it http://www.ford-trucks.com/how-tos/a/ford-f150-f250-how-to-clean-a-faulty-mass-airflow-sensor-361730


2

Yes, provided the following conditions are met: the units for the values MAF and fuel flow values are consistent. if you're using OBD-II parameters the values are usually in different units. In fact, fuel flow is usually volumetric (L/hr) and not mass flow like the reading from the MAF so you would have to correct for that by injector flow rate, I'm ...


1

Well, it turns out that the 1996 Ford E350 doesn't have a Mass Air Flow sensor - hence the trouble finding it :-) Instead, it has a MAP (Manifold Absolute Pressure) sensor, which looks like this: And can be found here: Thanks for your help with this!


1

There is no one-size-fits-all formula Perhaps an analogy can help explain why this is. The volumetric efficiency of an engine is analogous to a person's ability to fill their lungs with air. To continue with the analogy, the various OBDII parameters are like a person's vital signs, such as heart rate, blood pressure and O2 saturation. To say that the ...


1

P0100 A code P0100 may mean that one or more of the following has happened: The MAF may be disconnected, or a wiring connection may be bad The MAF sensor may be faulty If the MAF sensor element is dirty use disc brake cleaner. Do not use Throttle body cleaner because it will leave a residue that will muck up the sensor. A residue on the hot wire element ...


1

This is gas cap check valve. I tried to edit my post but It would let me. So here is a follow up for clarification. The check valve in the gas cap helps to regulate the pressure in the EVAP system.


1

Milan, I recommend that you purchase a paper Chilton's or Haynes repair manual for your car. They cost around $30 at your local autoparts store. Many manufacturers have provided a 'secret' code that you can use to turn your check engine light into a blinking code reader. The instructions for that tend to be written in the repair manual (not all ...


1

The Peugeot 207 petrols have a little bit of a reputation for clogging up on the throttle body. Using a tin of throttle body cleaner and a common bath room tooth brush, remove the hose to the throttle body. Spray in and around the throttle and clean off any 'dirt' with the tooth brush. Hold the throttle blade open and clean as much as possible in and around ...


1

In most cars, they are exactly the same between banks 1 & 2. In fact in a lot of cars, you could use the down stream sensors as the upstream sensors (this all assumes OBD2). So, yes, order exact for both sides. Secondly, the reason your car runs better when you pull the MAF is the same reason it runs the way it does in open loop. When you pull the MAF, ...


1

The 50 g/s max flow reading that you are getting is far lower than what merely altitude can explain. The chart above shows that at about 5,200 ft above sea level, the density of air is 83% of what it is at sea level (0.062 lb/cu.ft vs. .075 lb/cu.ft). So to account for the altitude, you should multiply your expected mass flow by 0.83. According to the VAG-...


1

The fault code P0171 descriptor is Bank 1 running weak. The fault code P0174 descriptor is Bank 2 running weak. This means that your engine has too much air or not enough fuel for proper ignition. This can be a faulty MAF sensor as it is common to both banks. It can also mean that you have an air leak between the MAF sensor and the throttle body, a faulty ...


1

The part you're pointing to is this one. EGR VACUUM SOLENOID Alternate/OEM Part Number(s): F57Z9J459C, F63Z9J459AA, ZZM32035A, ZZM42035A


1

I have a 2005 Hyundai Elantra, and I was getting OBDII error codes: P2626 Hyundai - HO2S Pumping Current Trim Circuit/Open Bank 1 Sensor 1 .. and later, I also got P2196 Hyundai - HO2S Signal Stuck Rich Bank 1 Sensor 1 My car was sputtering, somewhat intermittently. It would intermittently lose power rather suddenly while accelerating. The egine was also ...


1

These motors were plagued by problematic cylinder heads. Usually the end result in cases like yours are replacement of the Cylinder Head. Most likely there is either a blown head gasket or burnt exhaust valve. If there are no vacuum leaks and MAF is good then you need you start looking deeper into the engine.


1

It could be caused by ignition cables, coils, plugs, I have had the same problem in my Skoda Octavia ´00, in the morning it was like one of cylinders is not having a spark, combustion was very bad and power was reduces but only for max 5 minutes, then after engine got heated a bit it disapeared, also this problem is related to damaged gasket under the ...


1

I wish I had a clue or had watched this video before I spent over $600 way back in 2003 when my MAF went bad in my 2000 Sentra. The video should speak for itself: http://youtu.be/vPT8rL0noYg



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