I have an 05 with the 5.4 3valve. A couple weeks ago we filled up the truck and my boat motor at the same fuel stop. Both my truck and my boat motor started to run crappy. It was getting a misfire on 5 and 8 and lean on bank 2.We took the truck to our mechanic and they replaced the plugs and fuel filter. Still has the misfire. We've had the truck to 3 different mechanics noone can pin point it. Here is what I have done and had done. Compression check good. Fuel pump pressure good. Coil test good. Replaced the fuel filter. Pulled the fuel rail and checked for leaking or plugged injectors, they are all good with good even spray. Checked for vacuum leaks found none. MAF sensor cleaned. Checked PCV valve and hose its good.

The code its pulling is the p0174 lean on bank 2. All other codes have gone away. It idles a little rough but it has NO power at all. Seems to misfire worse at low RPMS (i.e. in over drive at around 50 mph). Under any load at all it misses bad too. I am at a loss for ideas here. O2 sensor? Catilatic Converter? MAF sensor? TPS? Any help would be great. I have searched these forums and have tried all I have read. Thanks for any advice.

D

 

My thought would be if both the boat and truck started to run like junk you got a load of water at the gas station.

I'd try some of that fuel dryer stuff and see how that goes. Unless you have a fuel system with a water separator the new fuel filter won't do anything for your problem.

The only other option is drop and drain the tank.

That would be my guess. Good luck.

 

The fuel we got has all been burned out. And we've almost gone through a whole other tank of fuel. We've put some fuel dryer in. With no affect.

 

Go to the basics. Swap coils with known good cylinders if that dont work swap injectors with known good ones. If that dont tell you then compression..

 

Coils check out good. Compression test is good aswell.

 

PCV and EGR would be my next shot at it.

 

The PCV valve checked out ok at a shop. What would the test be for the EGR though?

 

With it idling, disconnect the vacuum hose from the EGR valve, connect a long piece of hose to it, and suck on it. If the EGR valve is working, it will stumble and possibly stall. Feel the vacuum hose you pulled off the valve, there should be no vacuum on it at idle.

 

Where is the EGR valve on this truck?

 

Cylinders 5 and 8 are on bank 2. Replace the O2 sensor driver side upstream and that should fix your problem.

 

No, you don't replace an O2 sensor to correct a rich or lean code.

 

The only function of the upstream O2 is to rich or lean the fuel. Changing the duration of spray from each injector. That's why there is 2 upstream, banks 1 and 2. The 5.4l 3v does not have an EGR. Besides the EGR would be an equal vacuum leak causing lean conditions on both banks.
The extra fuel dumped from the misfires burned in the exhaust and damaged the tip of the O2 sensor.

 

The O2 monitors the EXHAUST gasses and tells the PCM if it IS rich or lean. One of the first monitors for the a/f ratio is the MAF, along with crank and cam and temp and rpm's and throttle position....

The O2 Reports results to the PCM for fine tuning-not the other way around. So to replace an O2 to correct a rich/lean condition is like changing paper boys because the news is bad.

 

Ok, I'll give you credit for the MAF, it is the first monitor of air density and temp into the engine. But, the oxygen sensor is the final influence for the injection time duration. MAF sensor can not be damaged by contaminated fuel. I would like to see the Long term fuel trim and the short term fuel trim readings also, the output voltage of the Bank 2 sensor 1 O2 at idle and 1200 RPM. I would bet the fuel trims for bank 2 are at the maximum and the B2S1 O2 voltage does not drop below 1volt.

 

What was the compression?
Where did you find a compression tester with the correct fittings?