A friend of mine has a 2000 Ranger 2wd with the 3.0 V6 in it. The truck has recently started running rough and through a check engine light. I pulled the code and got a P0171 (bank 1 lean). I briefly checked it over for vacuum leaks and found the hose that connects the PVC system to the air intake was off so I reconnected it and cleared the code. The truck ran a little better but the light came back on with the same code so I looked at the short fuel trim on both banks. Bank 1 was at 42% and bank 2 was around 2%. Thinking the O2 sensor must be bad I replaced it with a new one, cleared the codes again, and rechecked with my scanner. Same thing bank 2 in spec and bank 1 at 42% so at this point I'm at a loss. Is there a vacuum line that could be causing only bank 1 to be lean? Do these engines have any known intake gasket problems? Although I've never seen a injector go "bad" could this be a problem and if so would I not also get a misfire code? I know 5.0Ls and 4.6Ls like the back of my hand, but this is the first time I've ever laid eyes on a 3.0 V6 and don't know its ins and outs so any help would be greatly appreciated.

 

Welcome to FTE.

You said this 3.0L recently began running rough, so what event preceeded it's beginning to act out?????

What do the O2 sensor PID switching speeds look like, on your scantool????

Have you done a fuel injector listen test, to determine if you can hear a difference & maybe catch one acting out????

Any other codes found, including any pending codes????

 

pawpaw,

It's not mine so I can't say what was going on before my friend who knows very little about cars said something to me about it running poor. It's accually his dad's truck that he is barrowing so he knows very little about it too. I can tell you the O2 switching on both banks looks about the same, but then againg I don't really know exactly what to look for. As far as the injectors are concerned would you recommend I use a automotive stethascope to test them? There are no other pending codes and the P0171 comes back almost immediately after being cleared. If fact the CE light will flash when you give some gas and after a few minutes will say on. I can also say that although I've never driven a 3.0L I have driven the 2.9L and the 4.0L and a range of 4 cylinder trucks and compairing I think it's way down on power. I've also heard these engines can have EGR problems so I'm going to look at that next. Thanks for your help.

 

Well you can fashion a stethoscope from a long screwdriver, broom handle, piece of hose, ect & listen to each injector & maybe determine if one is acting out. The acting out ones' clicks should sound different.

If both O2 sensors were Quickly switching at about the same speed, I suppose we could kinda set them aside as suspects, for now. But if they were lazy in their switching speed, especially bank one, then maybe they still belong on the suspect list.

With this many miles on his ride, do you know if it's ever had the O2 sensors replaced, other than the one you did????

Has the MAF sensor ever been cleaned in all those miles????? I know it affects both banks, but maybe bank 2 is on the borderline of setting a code, but the system is still able to compensate just enough to prevent the code.

The fuel trim numbers, sure indicate something is going on with bank one.

Now if it were a 4.0L, we could suspect a leaky intake manafold gasket, as it's common on the 4.0L, not common on the 3.0L.

Doesn't mean it can't be leaking though, but you said you've done vacuum leak checks, but then again we don't know what kind of vacuum leak checks you've performed.

Have you hooked up a vacuum gauge to monitor the engine. A vacuum gauge can tattle on a number of conditions.

Just some more thoughts for pondering.

 

Pawpaw,

The truck has 98K miles on it and the bank 2 sensor was replaced by a shop less than a year ago the bank 1 sensor had never been replaced so I replaced it a few days ago. I briefly inspected the vacuum lines that I could see and only found the one leak that I fixed which helped but didn't fix the issue. I also checked the MAF sensor and it looks spotless. This coming weekend I'm going to replace the fuel filter, check the fuel pressure, connect and vacuum gauge, and give it a real good inspection for vacuum leaks. With a 5.0L I know where every vacuum line is, what is does, and where it goes. On this thing I'm going to have to hunt and trace them to see whats going on since I have no clue where they go on the intake. Is there a vacuum port on the intake of this thing that just goes to a cylinder on bank 1? Thanks for your help.

 

Did you replace the O2 sensor with a Motorcraft, or one that states it meets Fords design requirements & installed it to Fords specifications????

For instance some O2 sensors must breathe through their electrical connectors, so if we change the wires covering, or add a electrical grease to the connector, we can plug things up, or upset it's calibration, or operation.

Other physical design features will figure in on the response time of the O2 sensor & will affect how the computors program uses this feedback to control fuel trim.
So if the O2 sensors output doesn't fall within Fords operational parameter requirements, the computer may get confused.

An exhaust leak close to the O2 sensor can upset it.

I'm trying to think of things that would affect only bank one & also cause driveability problems.

Kinda hard to believe that all the injectors on bank one are dirty & clogged to the point that they are causing a lean code only on bank one.

Seems to me it would be kinda hard to have an intake manafold leak that only affects bank one too.

So, in the absence of any other codes, in my mind right now, I keep wanting to come back to the O2 sensor, as a corrupt, or out of tolerance output from it, could confuse the computer & cause it to foul up the injectors squirt time.

In other words, maybe something is causing the computer to think the air/fuel ratio is too rich on bank one & it's cutting the fuel injectors "on" duty cycle back.

Good idea to hook up a vacuum gauge to the intake & see what it indicates. I'm not familiar enough with the 3.0L's vacuum lines to know what might be available on the intake manafold, so maybe some 3slow members will chime in.

Things like an acting out EGR system, MAF, EVAP system, can cause a P0171, but you usually have other codes to go along with problems in those systems, not a stand alone P0171.

So maybe think about what could cause a bank one ONLY, lean condition.

Just some addtional thoughts for pondering.
Keep us posted on what you find.

 

The O2 sensor I used is a Bosch for this truck. I have checked the EGR system and EVAP system and they both seem fine. The funny thing is I did notice that bank 1's fuel trim seems to be between 0% and 8% at idle but when you give it some gas, is with it goes up to 42% and the check engine light starts flashing. Truck also seems to idle high at around 900RPMs, so I back to thinking vacuum leak.

 

When the CEL is flashing, that means there is a misfire occuring at that time and at that RPM. Initially I think you have to assume the misfiring cylinder is in Bank 1 (passenger side) somewhere.

I've heard of some similar vintage Ranger 3.0L's with valve problems causing similar symptoms, but I don't think you should jump to that conclusion yet. You should first check things likes the secondary ignition (spark plugs and wires) and make sure that the fuel injectors are all firing like they are supposed to.