I have a 2002 Honda Civic EX. I am having trouble with the
cars gas mileage and also with power. Here is what its doing: Every
time I get to a ¼ of a tank it runs really bad. At first when I am
starting my car it has to crank like 4 or 5 times before it will fire
up but if I crank it once or twice and then turn it to the off position
and then try again it will fire right up like it is suppose to. The
other things it is doing is it will stall out on me when I try to
accelerate and sometimes will die unless I ride the clutch. Then when I
am just sitting at an intersection it will stutter and bog out like it
wants to die. The catch to it is though when I am on a full tank it
runs fine except for the bad gas mileage. I am not a mechanic by any
means and I have taken this car to 3 different people and have gotten 3
different answers. I am tired of wasting my money with dishonest
The check engine light is on and it reads P0171 System Too
Lean (bank 1), but why would I be getting this bad of gas mileage. When
I say I am getting bad gas mileage I am getting about 200 miles to a
tank and anyone who owns a Honda knows that's horrible. The problems
that have been told to me are this
1. That I have a crack in my exhaust manifold.
2. I need a new fuel pump.
3. My fuel gauge is off and maybe a bad injecter
I have use some injecter cleaner on the car and still nothing
so I am hoping some one on here might be able to help me out on
figuring out what's going on so I can get my car back to normal
This _is_ curious, so I did a bit of digging of my own.
It seems the term "system too lean" paradoxically means you are
In short, the ECM is being told by the oxygen sensor that
the mixture is too lean, and it therefore attempts to enrich the mixture
through the use of "fuel trim", right up to its limit of adjustment.
But since the ECM never ends up being told the mixture has been
corrected, and having reached the limits of its "fuel trim" range
without obtaining the proper report from the oxygen sensor, it reasons
the system is still too lean and sets the P0171.
The question then arises: Why is the ECM being told the system is too
lean? There is no short answer. From this Toyota site
http://www.4x4wire.com/toyota/4Runner/tech/OBDII_ECU/ comes this list of
* Air Induction System Leak
* Injector Blockage
* Mass Air Flow Meter
* Engine Coolant Temperature Sensor
* Fuel Pressure
* Gas Leakage from the Exhaust System
* Open or Short in the Oxygen Sensor or associated wiring
* Oxygen Sensor Defective
* Engine Control Unit
You need to have a competent dealer tech sort this out. I'd guess about
$100 for diagnosis.
Tegger, excellent reply! Looking over the list, most of these items
would generate a code that would also show with an OBDII reader. So,
let's assume the person who gave this guy the P0171 knew what he was
doing and that was the only code. Just curious though... has this
owner ever replaced the gas cap, like, leaving the original at a gas
pump somewhere and picking one up aftermarket? Some caps are vented,
others aren't and the wrong one on the 2002 Civic will do weird stuff.
Perhaps an easy fix!
How many miles are on the car? Usually new O2 sensors nowadays fail
anywhere from 50k-70k miles. I would probably change that first since
the P0171 on most postings indicate a problem with the O2 sensor. This
doesn't necessarily mean that the O2 sensor is bad, but from the age
of the car, I would bet that is the problem.
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