Question about Cars & Trucks
I had P0171, P0174. Later, P0101 and P0102, then P0506. After looking under the hood at my Cold Air intake, since some of these are Mass Air Flow (MAF) sensor related, I discovered that my Cold Air Intake (CAI) was allowing fresh air to enter (not seated correctly) at the throttle body on my 2004 GTO with LS1 5.7. I removed and reconnected the CAI and made sure there were no leaks. The car now runs well and no new codes have appeared. I realize this was a late answer, but hope it helps others in the future. Bottom line, fresh air after MAF is a bad thing.
Posted on Jan 01, 2015
Sounds like a fuel delivery problem or a vacuum leak. Check fuel pressure. If the car is stumbling upon acceleration or trying to die at stoplights, suspect bad fuel filter or fuel pump. Check for vacuum leaks by spraying brake cleaner on suspect areas while engine is idling. If a change is noticed, you have found a leak.
Posted on Apr 01, 2014
P0171 p0174 indicate lean ...check for vacuum leaks around intake manifold...spray carb cleaner(or brake cleaner if flammable)around intake manifold..if rpm goes up you have a vacuum leak....fix leak ..clear codes and test drive.....at least two drive cycles
Posted on Apr 01, 2014
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Posted on Jan 02, 2017
SOURCE: PO174 HOW TO CLEAR THE CODE
Okay so the more oxygen in the exhaust (lean condition) the lower the voltage from the O2 sensor and the more fuel the computer calls for. Then the oxygen content in the exhaust drops (because it is being used up in the combustion process), and the voltage increases (rich condition) and the process repeats, for as long as the car is running, hundreds of times a minute. A gasoline internal combustion engine needs oxygen to burn the fuel. If the mixture is ideal (or 14.7:1) then all of the oxygen is consumed as the fuel is burned. The exact amount of fuel needed to produce a 14.7:1 air/fuel ratio varies with barometric pressure (altitude), relative humidity and fuel quality and condition; thus the need for oxygen sensors.
So knowing all of this what should we check when we have those pesky rich or lean codes? The most common issues for lean codes are:
1. Vacuum leaks - check for failed or loose vacuum lines, leaking intake gaskets, intake air tubes loose or any other source of un-metered air leaks (leaks after the Mass Air Flow Sensor)
2. Restricted fuel filter or bent/pinched fuel system lines
3. Incorrect input from other sensors, such as the Mass Air Flow Sensor, which may not always drop a separate code
4. Engine misfire – Yes I know this one may seem weird. You might think that if there is a misfire then you will have all that unburned fuel and it should read rich; right? Well the O2 sensors read only oxygen content in the exhaust, so if you have all that unburned fuel from incomplete combustion then, you guessed it, you also have all that unburned oxygen. High O2 content in exhaust equals a lean reading!
There are also some other possibilities such as an internally leaking EGR system, (but this will typically set a separate code). A leak in the exhaust system before the O2 sensor will also cause incorrect readings. And always check for after- market modifications. These can throw a wrench into the works! The only other possibilities (however unlikely), are wiring issues, computer concerns or a bad O2 sensor!
P0174 is a Lean condition on the side of the engine where cylinder # 2 is. Good luck and hope this helps.
Posted on May 01, 2009
well i'm sorry that you got the miss information here on fixya. because all internal combustion engines need a pcv valve to operate properly.
now the information you got first is correct and pcv valve can set false codes like o2's and lean bank conditions also can cause you vechile to run or idle rough.
no there are a few different styles pcv valves and some times don't look like your convetional pcv. some are heated in different ways either by coolant ( witch look like a conventioanl pcv but with a coolant tube around them) then electricaly heated and they don't look like them at all. but one thing that has to stay the same is the pcv valve has to ventilate the crank case and will be found somewhere on or near the valve cover because it is the easiest and most accessible point of the engines crank case area. so i would look for that and usally on that vechile it is on the passanger side valve cover in the middle.
with that said and seeing you did all those repairs i would go right for that as my next step. but there is other thing that cold cause this issue like leaky injectors and is almost more likely becuase of the o2 sensor code and backfire. do you have the code # so i can look it up and best assist you?
see vechiles are hard to fix over the computer as i am trying so if you have any more question/info about this issue please ask and i will be glad to help.
Posted on Sep 22, 2009
Testimonial: "Cool thanks, i'll check the pcv valve/ line going into the back of the intake, if that doesn't work i'll go for the codes again....thanks again...."
Check the wire leads and clean them before reconnecting the wire leads. It wouldn't hurt also to clean the MAF sensor with MAF cleaner, the code your getting is most common to the high performance oil base filters like K&N.
Good luck and this should help you resolve your MAF issues. Thank you for using Fixya
Posted on Mar 12, 2010
P0100 OBD-II Trouble Code
Mass Air Flow (MAF) Circuit Malfunction
Basically this means that there's a problem with the Mass Air Flow (MAF) sensor or circuit.
You will likely not notice any serious driving problems, but there may be symptoms like a general decrease in power or sluggishness.
A code P0100 may mean one or more of the following:
* The MAF may be disconnected, or a wiring connection may be bad.
* The MAF sensor may be faulty.
Use an OBD II Reader (or go tou your local parts store and they will for free) and reset the code and see if it comes back.
Then start with the cheapest, easiest repair procedures:
* Check the Mass Air Flow Sensor wiring/harness is connected properly and that there are no broken / frayed wires.
* Unplug and reconnect the MAF wiring harness a few times to clear the contacts.
* Check the voltage of the MAF sensor (refer to a repair manual for vehicle specific information).
* Replace the MAF sensor.
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Posted on Sep 28, 2010
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