For the past year, my 2000 Dodge Stratus SE (2.4 engine) has been plagued intermittently by a check engine code, PO171 - Lean Fuel Condition. This vehicle has nearly 150,000 miles on it and has been maintained in accordance with the manufacturer's recommendations.

About a year ago, I was driving and received two engine codes: PO301 - Cylinder #1 Misfire and PO171 - Lean Fuel Condition (Bank #1). I cleared the codes using a borrowed scanner and the codes cleared. A few weeks later, the vehicle coded again but this time only the code PO171 appeared and has been with me intermittently ever since.

I've received many suggestions to possibly remedy my vehicle's problem but none have been successful to date. I've changed spark plugs, spark plug wires, PVC valve, replaced the "Bank #1" oxygen sensor twice (once with an aftermarket and once with a factory one), looked for exhaust leaks and even had the car smoked to no avail. The pressure from the fuel pump is good (that was replaced only 40,000 miles ago) and the timing belt/water pump were replaced nearly 60,000 miles ago (no problems back then).

In the past few months, I've noticed a change in the vehicle. When starting the vehicle, the vehicle will start and run smoothly 95% of the time. But the other 5% of the time, the vehicle will run extremely rough and often the code PO171 is not far behind. Once the PO171 code appears, the car "sucks" gas and lacks power until started again (smoothly) or the code is cleared (either by scanner tool or on its own).

Another thing I have noticed is that when the engine is under certain stresses, the PO171 code is more likely to appear. Often when you have to get out into traffic and get on the gas pedal, the engine code appears. This is especially true if you are going up a slight incline as well. Where I live, there are two (medium sized) hills that cause the vehicle to code nearly every time. Yet, the code never appears when using "cruise control."

If anyone has any ideas, please feel free to let me know. This vehicle used to consistently knock-off 27 - 28 mpg in the warmer months and now 24 - 25 mpg is the best we can do.

 

You ignored that P0301. That may be the root cause of the problem. Every time you wipe out the memory, it takes a while for the misfire monitor to start counting again, so...you won't see the P0301 most of the time, even though you feel a misfire. If your fuel level stays at or below 1/4 tank, the misfire monitor will NOT reset.

 

Thank you for the feedback. I've always been suspicious of the PO301 engine code but I was told to discount that code. First, the code has only shown up once, when the PO171 engine code began to appear. Since, its been non-existent.

Second, the PO301 engine code was determined to be the result of a bad spark plug in cylinder #1. When the spark plug from cylinder #1 was placed in cylinder #2, cylinder #2 then began to misfire (PO302) and cylinder #1 was fine. At this time the spark plugs and spark plug wires were replaced (I've never had spark plugs last more than 23,000 miles in this vehicle, even platinum spark plugs).

Since my last post, I have noticed that in addition to the conditions I listed in my original posting, when the car is at or exceeds 2100 RPM's, the check engine light is most likely to come on (and once again going up hill). I've also noticed a distinct misfire when the check engine light comes on and the PO171 engine code is displayed. The misfire is only detectable through the exhaust pipe though. So, the search continues!

 

Mkay, you left that out of your first post. Hey, you could be a service advisor...lol. Mine give me 2/3 of the story most times if i'm lucky! (: J/K


You're probably going to have to catch it happening with a fuel gauge on it. Also go back and look at your O2 wires very carefully and see if they are rubbing something.