Bank 1 runnning too lean?

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

S

samsher213

10 Year 15 Year
Joined
Feb 13, 2008
Threads
13
Messages
85
Location
Durango, CO
so my check engine light came on and the scanguage is giving me P0171 for a code. i have searched here and on the internet and found that it means Bank 1 is running too lean. i am pretty mechanically inclined but dont know a whole lot about the 100s. can someone translaste this into english for me...like what is the difference between the 1st and 2nd bank, and how do i richen the mixture to make the light go off? and what else may i need to check out for this code? note: i am from the eastcoast (sea level) which i am guessing has something to do with it. thanks for the help

sam
 
The banks are the rows of cylinders in the "V". I can't remember which is which on the 100, look for a cylinder diagram that's posted around here somewhere.

There's no way to manually adjust the mixture, it's set by the ECU. I'd start looking at the fuel and air system:

- air filter
- fuel filter
- fuel pump
- throttle body
- MAF sensor
 
Would a clogged/dirty injector or injectors give this result. Or would throw a code for the individual cylinder? Or is his terms off and instead bank=cylinder #1?
Sorry more questions that help.
 
Bank 1 Sensor 1 is probably bad and giving false readings to the ECU.

If it's a bad O2 sensor, and the ECU thinks that Bank 1 is lean, then it will compensate by increasing the fuel mix to Bank 1. When it does that, it will run really rich, and you will see tell-tale evidence as black sooty buildup in the tailpipe if it's been doing it a while.

If it were a malfunctioning MAF or fuel system, then it wouldn't be just Bank 1, it would be both sides.
 
Seems like you might be able to hear a hole in the muffler.
 
If the hole is downstream of the O2 sensors, etc. etc., I don't understand how it would throw a code. I'm betting on something like the bad oxygen sensor. That makes more sense.

Oh, and after you fix the code, yeah, you should probably fix the muffler. ; )
 
FSM shows the following "trouble areas" to check for the P0171:
- Air Intake (hose loose)
- Fuel line blockage
- Injector Blockage
- O2 Sensor
- MAF
- Engine coolant temp sensor
- Gas leak on exhaust system ;)

You can also get the code if you ran out of fuel.
 
Just wanted to add to this thread based on my experience today. I had my Check engine light come on yet my car seemed to be running fine. The Code was P0171. The first thing I did was clean the air filter and then disconnect the battery to reset the CPU to see if the code would come up again. After starting my truck up it immediately was running like s*** and idled very rough. I still have no idea why it all the sudden did this. So today I went and bought a new air filter, a fuel filter, injector cleaner and electronic cleaner spray. I swapped the fuel filter (which was super super old and gunked up), cleaned the MAF sensor, swapped the air filter, and poured in the injector cleaner. I had replaced my starter a few months back and wanted to make sure that the intake manifold bolts were tight. To my surprise I actually was able to tighten them up quit a bit. After disconnecting/connecting the battery again I started her up. The truck still idled terrible. I drove it for thirty minutes and the light never came back on. The truck actually continued to run better and better and then started idling more smoothly. After about 2 hours I went for another drive and the problem seems to be fixed.

Im not sure exactly what I did that made the difference but I spent only $60 at the auto store and 45mins under the hood. So far so good.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom