Ok, first off, I have a 99 Ranger 4.0 4x4 with 113k miles on it.

I've had rough starting for a while now, but it's never really been a big deal. You start the engine, it has a very rough idle for 2-3 seconds and then idles up normally.

The other day, the check engine light came on. I read the code using a code reader and it shows up with a P0171 code - Lean condition bank 1. No big deal because I knew I hadn't changed my fuel filter in a while and figured this was the problem. I took it to a local service center and had them change it when I had the oil changed.

Now, several days later, the CE light came on again, this time showing P0171, P0174, and P0300. The first two are lean condition codes and the third is a random, mulitple misfire detected.

I checked the fuel filter and noticed the fuel flow arrow was pointed back towards the tank. I asked a friend that used to work at a Ford service center and he told me this might actually be correct, as there are two lines from the fuel tank.

It seems odd to me, but I think the guys at the service center might have put the fuel filter on wrong. Does anyone know which direction it goes for sure?

I know it's not the IAC, because I changed that out about 30k miles ago. The MAF I've never cleaned or changed so I'll check that, and I use a K&N air filter that was cleaned about 10k miles ago.

Can anyone think of another suggestion to help solve the problem?

Oh yeah, plugs and wires are about 30k old too.

 

I just recently changed the fuel filter in my truck and the arrow pointed towards the front of the truck as that is the direction of flow. Could be fuel qaulity or a vacuum leak somewhere. Do you notice any lack of performance? How many lines do you have going to the fuel filter, not sure when the 4.0 went with a returnless system. I know mine is returnless as I have three lines at the fuel filter. If you have three as well then there is only one way the filter can go on.

 

how rough are you on your truck?
if you are really rough on it it may be the Distributor
also take a flat head screwdriver to all of your injectors and make sure they click. If it hessitates alot its most likely a fuel injector or carbon build up on the pistons. If you use crappy gas its gonna give you problems

 

Distributor??

 

I'm not sure what its called on the rangers

 

I don't really notice a lack of power, at least not one that 113k miles didn't bring, but I did notice a sound today.

When I begin to move from a stop in first gear, I hear a "crinkle" type sound. Kind of like water dripping onto tin foil.

As for the fuel lines, I can only see one, but I think there's two there - the other being farther back into the frame.

I'm still thinking its because of the fuel filter and the directional flow on the filter being backwards, but I tried once to change the filter and even with the disconnect tool was not able to get the line off.

 

My truck does the same start up thing. So did a friend of mines 99 4.0 4x4. He had his fixed under warnatee. They changed both heads (and gaskets respectivly) and that fixed it. Mine is one cylander, and it fouls plugs and causes a miss, about one plug every 5-6 months. Thats something to think about for your start up problem...

 

If you only have two fuel lines then the arrow for flow should be pointing torwards the engine.

As far as the heads it could be a leaky gasket or pourus head cause a slight bit of coolant to get into the cylinders causeing a miss, a leaky fuel pressure regulator can cause the same affect but in your instance that would be setting a P0172 and P0175 if it was the FPR.

 

But do you think that simply a improperly installed fuel filter, causing the lean bank conditions, could also be causing the misfire problem?

 

Yes

 

and if you dont wanna replace the head gaskets try giving it a motor vac...its good for the engine...but deffinetly check the flow of the fuel filter first

 

Alright, a little update....

I've changed the fuel filter, this time putting the flow in the proper direction. I noticed my gas mileage came up from before I changed it.

I reset the codes, hoping all would be well...

After several weeks of driving, it came back on.... to attempt cheap remedies, I did the following...

Cleaned the MAF, temperature sensor, changed the PCV Valve, changed the plugs (none appeared abnormal), and flushed the intake using seafoam.

Since using the seafoam, my rough start/idle problem has gone away. I disconnected the PCM and started it up. It didn't take 2 days for the PCM to spit the same two codes back out, P0171 and P0174.

Can anyone think what else this may be? There doesn't seem to be a stumble at idle, so I don't think it's the injectors or a cylinder.

 

Mixture codes are among the most difficult to diagnose because there are so many possibilities. Setting aside the items that you've already eliminated, here are a couple of more guesses:

Check for any unmetered air leaks, especially in the PCV hoses or intake manifold gaskets. These are both common leakers.

At 113K, your oxygen sensors may have become tired and they could be misreporting the mixture. This problem can give you lean codes and reduced fuel economy.

 

I guess I should have added that the bank 1 O2 sensor and the O2 sensor behind the cat were both changed around 15k miles ago, so I doubt it's the O2 sensors... <sigh>

 

usually lean back 1/2 are failing 02 sensors...id check what bob suggeted.

has the idle been rough lately again?

 

Not really that I've noticed. The only thing I have noticed lately is the "marble" sound at idle seems to be a little louder than it used to be.