What causes P0172 - Fuel Trim too Rich (Bank 1) [2001 Honda CR-V]?

Question

I have a 2001 Honda CR-V SE. A couple of months ago it started idling low and a couple of times on the freeway it was jumpy...
Soon after that, the engine check light came on. I went out and purchased an OBD-II code reader and SW... The code I got was P0172 - Fuel Trim Too Rich (Bank 1).

I did a freeze frame and this is what I got:
Short Term Fuel Trim - Bank 1: 1.6%
Long Term Fuel Trim - Bank 1: -16.4%
Intake Manifold Absolute Pressure: 80kPa
also some other readings (speed, rpm, load value, coolant temp, etc... which don't seem to important)

1. Does anyone know what causes the fuel trim to be too rich?
2. Does anyone know where I can get the specs for all the sensor readings for the car so I can see what is in spec vs. out of spec?

Your help will greatly be appreciated...

Here are more details in US units...

Fuel system status: Closed loop
Calculated Load Value: 20%
engine Coolant Temperature: 187F
short Term Fuel Trim: -28.9%
Long Term Fuel Trim: -3.1% (but varies a lot)
Intake manifold Absolute Pressure: 6.2 psi
Engine RPM: 1747 rpm
Vehicle Speed: 42 MPH
Ignition Timing Advance for #1 Cylinder: 34 deg.
Intake Air Temperature: 93.20F
Absolute Throttle Position: 11%
O2 Sensor Bank1 Sensor1: 0.585V - -17.2%
O2 Sensor Bank1 Sensor2: 0.895V - -20.3%

I did a sensor reading while driving the vehicle (well not me driving ;-)

Answer 1

Look at the values again! Read the long term and compare with the short term.
The LONG term is trying to TAKE away fuel, and a LOT of it, not add it
There is a condition somewhere causing the computer to "see" too much fuel and tries to reduce it.

Possible causes
EVAP system failure (Should set a code)
Fuel pressure high
Coolant temp sensor (Should set a code)
EGR system failure
MAF slightly out of range (Should set a code if it is severe enough)

Your car doesn't use an oxygen sensor for fuel control, only for monitoring the CAT; fuel control is handles by what is called a WIDEBAND AIR/FUEL RATIO sensor, and they are very expensive. They are in the place of the front oxygen sensor, and their purpose is to maintain very close control of fuel so as to keep LAMBDA as near perfect as possible.
It would be smart of you to purchase a HONDA shop manual if you are going to repair the little car yourself.
Then read and understand the strategies used for fuel control and powertrain management, and follow the proper diagnostic and repair procedures discussed in the manual.
If you choose something other than a HONDA manual, you MAY be spending bad money, as Haynes, Children's, Clymers and others don't really delve that deeply in the computer controls for emissions.
Otherwise, you would probably be money and time and effort and frustration ahead to take it to a dealer or a REPUTABLE EMISSIONS repair shop displaying the ASE Shingle for the diagnostics and necessary repairs.

Good Luck

Answer 2

If it's a 4 cyl you only have one bank. So have you checked the air filter yet. Cuz that's my first suspect < not enough air >

If you replaced the air filter and it still does it, clean the MAF sensor. < dirt can cause them to overestimate air flow>

next do a fuel pressure and fuel leak down test < excessive fuel pressure or a leaky injector could cause that >

remember (this is difficult for most guys to grasp ) the sensor does not see how much fuel you have in the exhaust, It can only read oxygen levels. So, rich means exhaust gasses are nearly void of any oxygen.
The long fuel trim reading of -16.x indicates that your computer has seen the rich condition and is correcting for it by cutting back on injector pulse width.
Now change that filthy air filter.

Because if it were being caused by an excessive fuel or overfueling condition you'd have black smoke and it wouldn't make it chug when cut back occurs, and your exhaust would be glowing red hot.

I don't know how much a Kpa is, I need it in psi.
or better yet Hz

Answer 3

You really should have posted the other values also, because if you have a engine coolant temperature sensor it can make your car burn rich. Also it could be related to the oxygen sensor. There are a number of things that could make the light come on. Your best bet would be to take it to a mechanic and have them do some tests to verify the problem.

Answer 4

If it incredibly is a 4 cyl you in basic terms have one economic organization. So have you ever checked the air clear out yet. Cuz it is my first suspect < no longer adequate air > in case you replaced the air clear out and it nevertheless does it, sparkling the MAF sensor. < airborne dirt and dirt can cause them to overestimate ventilation> next do a gas rigidity and gas leak down attempt < severe gas rigidity or a leaky injector ought to reason that > undergo in concepts (it is complicated for many adult men to hold close ) the sensor would not see how a lot gas you have interior the exhaust, it may in basic terms study oxygen ranges. So, wealthy capacity exhaust gasses are almost void of any oxygen. The long gas trim examining of -sixteen.x shows that your laptop has considered the wealthy condition and is correcting for it by capacity of reducing on injector pulse width. Now substitute that filthy air clear out. using fact if it have been being brought about by capacity of an severe gas or overfueling condition you will possibly have black smoke and it does no longer make it chug while minimize returned happens, and your exhaust could be gleaming pink warm. i do no longer know how a lot a Kpa is, i want it in psi. or extra helpful yet Hz

Answer 5

2001 Honda Crv Value