Ford Ranger 2001 Lean on Bank 1

Hello, I have a 2001 Ford Ranger. It is a 4.0 and has a little over 200,000 miles on it. I have spent more money on mechanics that havent fixed the issue then the truck is probably worth. I have fixed the spark plugs, spark plug wires, fuel filter, mass air flow system, all o2 sensors, coil pack, taken cat off and looked at it and cleaned it. I have loss of power going up hills or when its cold out. I can reach 35-40 mph tops going up hill. And my truck shakes when I accelerate. Could it be a vacuum leak or a bad fuel injector? I cannot afford to keep bringing it back to the garage so my dad who is really good at working on vehicles is going to fix it. We are just trying to figure out what it is before we replace another thing that isnt the problem. Thanks in advance! Also the 3 codes I had before I replaced the fuel filter were : P0171, P0442, P1131. After repkacing fuel filter it seemed okay that day then the light came back on and started acting up again.

Your title says lean bank 1 but you don’t tell us how you know that nor the OBD2 code that you are reading. You’ve just told us a bunch of replaced parts but no reason for replacement. Were these parts determined to be bad or were they just replaced blindly in an attempt to get this truck to run?

Cleaning a catalytic converter is a waste of time. If they clog, they won’t clean and if they stop working, cleaning won’t help either.

Based on this, have you run a compression test? It is key to determining if the engine itself is in good enough condition to warrant replacing any more parts.


These parts were replaced by a mechanic. We replaced the fuel filter ourselves. I wrote the codes after realizing I forgot them. It has 3 codes.

I am new to this. I will try to do a better job giving more information.

So give them to us.

AND answer this…

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The codes are listed in my main post… P0171, P0442, and P1131.
I cannot answer the compression test question until I talk to him because I am not certain if the mechanic did it or not when replacing other stuff. He just said that based on my back bed he wouldnt put alot of money into it unless I am going to run it as a farm vehicle.

Not in the original post, only the edited one. You have an evap leak that needs a smoke test. And you engine is showing a lean condition on bank 1. Sounds like the mechanic threw parts at it hoping the problem would go away rather than actually finding the cause. I could be wrong, but if he didn’t run a compression test when the plugs were out, you should find a better mechanic.

What does that mean? A rusty truck bed?

Yes my back bed is really rusty. And yes I agree a better mechanic is needed. The evap leak has nothing to do with it running lean on bank 1 though correct?

If the truck bed is rusty enough for a mechanic to say he would not put money into the vehicle then there may be rust on parts that make this thing unsafe.

He said not to put money into it unless im going to replace the back bed with a flat bed. He said the rest of the truck is fine. He just based on miles and the back bed he didnt want me to waste my money fixing it when it may not be worth it at 200,000 miles.

Compression test will give you the answer or the next step to take.

Have you checked fuel pressure?

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We had bad o-rings on the plenum that threw that code.

Connect a fuel pressure gauge and monitor the fuel pressure while driving up hill.

You don’t need a compression test for a fuel system lean fault.