Year: 1999
Make: Dodge
Model: Stratus
Engine: 2.4L
Mileage: 161,000+/-

A couple of months ago, the check engine light on my Stratus began to display periodically. I had the car scanned and two engine codes showed, PO171 - Lean Condition and PO300 - Random Cylinder Misfire. I changed the plugs and the ignition wires which helped but didn't solve my problem. The plug from cylinder was heavily covered in carbon.

In the months since, I've continued to drive my Stratus but still I am experiencing issues with one of the two engine codes, PO 171 - Lean Condition. Sometimes the engine code resets itself, sometimes you have to reset it via scanner. When the code displays, often the car's idle is best described as rough, sometimes you can hear it missing through the tailpipe, the car will lack power (like being stuck in gear) and is eating gas up at a rate faster than before (I get about 80 miles less per tank now).

At my last inspection, I mentioned my troubles to the mechanic. The car passed with flying colors, no codes to be found. He suggested I bring the car back the next time the check engine light displayed which I did. To date we've changed the plugs, the ignition wires, the coil pack, the air filter and upper oxygen sensor (factory) to no avail. Getting tired of spending all of this money at the mechanic's, I began to investigate myself.

I recently invested in an inexpensive scanner and found my Long-term Fuel Trim values to be extremely high (15% - 24.2% generally). I was told this was likely due to a vacuum leak in a hose somewhere which I was able to locate and replace. This has dropped my LTFT's some (8% - 16% generally) but not nearly to normal and my check engine light continues to periodically display. The car's idle and gas mileage have also improved.

Today I sprayed down the engine with carburetor fluid to check for air leaks, none. A friend even did the 'propane' test. I also rented a fuel pressure test kit and found my fuel pressure at the fuel rail to be low, 32 psi when it should be 49 psi. I am being told that this is still likely due to a vacuum leak since my LTFT is still high but my research has led me to think maybe it is a fuel pump/fuel filter/regulator issue? Does anyone have any ideas? The fuel pump was replaced as a whole unit roughly 74,000 miles ago.

 

Have you experienced any hard starting at all?

 

Thank you for the reply. I have experienced some hard starting with this car. When you start the car, occasionally it will start but stumble as if it were fuel starved and stall out. If you give it a little gas when this happens, typically it will keep running. I have had this issue with the car since I bought it with 31,000 miles on it. The dealership could never find anything wrong but replaced the entire fuel pump assembly, plugs and oxygen sensors under warranty but the hard starts continued.

 

I had hard starting and some stumbling as I was driving. When I checked the fuel pressure it was just under 50 psi at the rail, but with key on, engine off it was zero where it should have held at least 20. I put a new fuel pump and filter in it and it's been fine.

A common issue is that mechanics almost never clean out a tank when they put in a new fuel pump. If you have crap in the tank the inlet strainer is going to get clogged quickly and you're right back to where you were before the pump was replaced. It also makes the pump work harder so it wears out faster.

 

Thank you for the feedback. The stumbling when starting is periodic but it may be a sign as you've pointed out. Its most common after sitting overnight.

When I conducted the pressure test, I had a pressure of 32 psi all around. I also had the fuel neck replaced about a year or so ago (that slipped my mind previously). In any case, it looks like I am going to have to drop the tank.