Bank 1 / Bank 2 Too lean

[p38fln]

Had this 2003 ranger for just under a year now, and the check engine light has started coming on. A code scanner gives two codes - Bank 1 lean, bank 2 lean. I also noticed that the misfire count went up by 1 when the code went to pending, and then went to 2 when the code went active, and at the same time there was a fairly loud ticking sound coming from the engine.

The freeze frame data said that the fuel mix was at 99% when the code was triggered, this is almost always at about 5% when I just look at it with the data feed.

Tried running 91 octane no-ethanol/oxy gasoline and clearing the codes, the problem came back in two drive cycles.

Looked carefully under the hood and noticed all of the spark plug wires going to the right side of the engine were touching each other, and the insulation had mostly worn off the parts that were touching.

Unplugged all the wires and routed them so they didn't touch each other anymore - the ticking sound was gone. The check engine light came back on a week later with the same bank 1 bank 2 lean code and showing a misfire on the misfire counter.

What are the possiblities that new spark plug wires could fix this? It seems somwhat random and always related to a cylinder misfire.

 

[Big Jim M]

From your description I'd venture a guess that about 99-1 for new wires would be the Vegas odds.
Big Jim

 

[snoman6115]

i had the "both banks lean" code and turned out to be a vaccum leak. the upper intake was leaking, replaced my valve cover gaskets, they were leaking slightly, and now i dont get that code. easiest is to replace wires first and plugs. all else fails look for vaccum leaks

 

[trader007]

when i got that code, first cleaned my maf sensor (carefully too!). that helped, but i soon found out 1 o2 sensor was bad, so i replaced all 3 of them. that helped tremendously, but it still wouldnt keep the light off for more then a day or so. im pretty sure it was still running in open loop the whole time

finally, replaced the pcv valve and that finally did it. i know in my case i had other problems, but no reason not to check the simple things first. like snoman says, vacuum leaks/plugs can cause this code in a heartbeat!

 

[01_ranger_4x4]

as stated earlier, its most likely a vacuum leak. there are two elbows near the intake plenum on these SOHC 4.0's that crack and begin to leak vacuum (see photo below) its a very common issue with these motors but its a simple fix.

 

[Yellowsplash]

as stated earlier, its most likely a vacuum leak. there are two elbows near the intake plenum on these SOHC 4.0's that crack and begin to leak vacuum (see photo below) its a very common issue with these motors but its a simple fix.

Vacuum leak, vacuum leak, and lastly vacuum leak...dont even dare touch your O2's. Above is a pefect picture of what happens. I help customers replace one about once a week due to this problem. Once you are for sure there is absolutely positively no vacuum leaks, I'd think about venturing elsewhere. Your fuel trim tells you everything...

 

[p38fln]

I plugged in my scan tool in and got these results (I tried to only select the ones that would matter)
Coolant: 192 F
ST FTRM1: 7.0%
LT FTRM1: 24.2%
ST FTRM2: 2.3%
LT FTRM2: 24.2%
Fuel Sys 1: CLSD
Fuel Sys 2: N/A
MAF Gr/Sec: 4.26
ST FTRM11: 9.3%
ST FTRM21: 3.1%

 

[p38fln]

Found the leak, the #1 cylinder is leaking at the air intake gasket.

 

[p38fln]

All but one of the intake gaskets were leaking slightly but the main leak was the elbow on the PCV vacuum hose.

No more leak - The O2 sensors are all bouncing around 0% +/- now.

 

[Yellowsplash]

Good to hear you found it...