171 and 175 errors at the same time
 

I have a 2001 4.0 SOHC Ranger. I am getting 175( Too rich on bank 2) and 171 (too Lean on bank 1)error codes at the same time. The engine has low power and uses lots of gas. Would this be a bad O2 sensor? If so which one.

Bank 1 is the passenger side.

Ok so I would check ur PVC hose and make sure there is no vac leak. I'd make sure there is no vac leak at all while Im at it. I would clean your MAF sensor too. I would also check your plugs and wires. Try switching your plug wires around to see if maybe you have some bad wires. Could be a bad coil pack too. I would first check for vaccum leakes and clean the maf and wipe the codes. If they return I would start looking at your plugs, wires, coil pack. O2 sensors rarely go out on fords from my experience.

I did a vacuum leak check, I could find no vacuum leak. I am pulling about 17 in/Hg vacuum at idle. I did a leak check around the intake manifold using the carb cleaner method, no leak detected. Tried a new PCV valve. Pulled the wires off the coil pack one by one while engine was idling, I saw good spark on all coils. MAF is new

I also get missfire errors 304,305,and 306 which are missfires on cylinders 4,5,and 6. I assume because the computer is setting the fuel to that side too lean to compensate for the too rich error it is recieving on the 02 sensor. Does this mean that the 02 sensor on that side may be bad. Or would the too lean from the other bank cause the misfires on 4,5,and 6

Plug wires are the next thing, they should be replaced anyway.

Any ideas?

There should be a curved 90 degree elbow on the passenger side near the throttle body, it connects to the intake on one end and a hard tube on the other end. Its about 3/4in in diameter. I have seen alot of them that suck together and over time will develop a hole in it.

Jimmy

Make 100% sure wires are not crossed, it could be a bad crank position sensor or something along that line telling your system to fire at the wrong time. Whats your fuel pressure like? What do your plugs and wires look like? Also check the hose that splash is talking about, they usually get soft and colapse making a vacuum leak. Coil pack could also be bad too....

BINGO! Thanks 8secSplash!. That is exactly what happened. Ford by the way makes you buy the whole tube assembly that goes from the PCV valve to the intake manifold $38 :irked:

:104[1]:

Glad I could help.


Jimmy

LOl I just reread my first post I put PVC instead of PCV hahaha. Anyway glad u solved your problem!

I still had some misfires and lean/rich codes. I took the intake manifold off. It was obvious the codes were right. You see bank 2 was more discolored than bank 1. I inspected the intake openings closely and noticed leaking on cylinder 1. I went to Ford to get new Intake manifold gaskets. I had a new set of FelPro gaskets in there previously. The FelPros were thin, sloppy in the grooves, and hard to keep in place while installing the Intake. The Ford gaskets were twice as thick, fit snugly in the manifold grooves and sealed great. The engine no longer misses, no lean/rich codes and run greats.

This the second time FelPro let me down. From now on I am a OEM only guy. They may cost me more, but I have to only do the job once. The amount of gas wasted on the FelPro crap would have paid for several sets of Ford gaskets.

The OEM ford gaskets are actually very good. It's all I'll use anymore. Even on my 800hp lightning the stock gaskets hold up better than any aftermarket version.

Rich