I've been chasing the dreaded lean bank 1 and bank 2 error codes, which i really didn't care, but the rev limiter kicking in i did. This has been a problem for better than 8 months and i finally got it to stop. Now not quite a fix, but a work around.

At this point i have done all the O2 sensors the big three the brake booster line, MAF, upper and lower intake, plus but i was still getting the dreaded lean codes.
I started by disconnecting and plugging both vacuum lines from the EVAP purge valve, but i was still getting the lean codes as well as the rev limiter kicking in at 3k. I left both vacuum lines plugged, but then unplugged the wires leading to the valve. This caused the car to throw an immediate code for the EVAP, but the car ran perfect. The following morning I hit the highway, and the next three days i traveled from Florida to New Hampshire in the high speed lane, with no rev limiter kicking in at 3k rpms or lean codes. All in, I traveled better than 1200 miles in three days. Where the car is running really well, i am looking for technical feed back on if this can cause any damage to the car?

Now comes that part that doesn't make sense. At highway speeds the car seems even smoother than before, and the fuel economy has increased substantially. Heading North, one leg of the trip when the temp dropped below 85, I hit 29 mpg and averaged 26 most other tanks full of gas. Prior to disconnecting the valve, I was averaging around 21.

Either way, the lean codes are gone, and more importantly the rev limiting problem is gone.

Hope this helps someone else.

It is bed time in my time zone, so i will check back in tomorrow.



Ron

 

No idea if this would cause any damage, the only thing I would suggest is that when you change O2 sensors be sure to use Denso originals as there are plenty of cases (including mine) on here of aftermarket ones still throwing the codes.

 

Thank you for your reply,

I did Denso and Bosch for O2 sensors.

Ron

 

If your car really isn't running in a lean condition anymore, then the ECU is not having to increase the fuelling to try & compensate for the lean running & your MPG will increase overall.

 

I only use Denso,very sensitive are our X types

 

RONKS, from what you describe, you have an EVAP solenoid that is failing and dragging down something in the ECU. I would look at getting a new EVAP solenoid and replacing what you have. I have had issues in the past where I was getting the "small leak" code (P0456?) and I found that if I took off the EVAP solenoid and cleaned it with some carb cleaner, when I reinstalled it, the car ran much better.

 

Hi Thermo,
I have a new valve waiting to go in, but i would like to check the rest of the evap system out. Should the vacuum line heading back to the canister hold vacuum, and if so for how long?

Thanks,

Ron

 

Ronks, it is not going to hold for too long. It is going to vary based on how much fuel you have in the tank. A fairly full tank will result in a quicker dropping vacuum than a fairly empty tank. The car simply tries to draw a slight vacuum and if it can, then it calls the "small leak check" sat. If that fails, then it tries the other valve and it has a slightly bigger orifice to see if it can draw a vacuum on the gas tank. If it can, then it knows it is a small leak. if it can't, then it is a big leak. Things like a leaking gas cap or the vent valve on the charcoal canister leaking can have an affect on things. I cannot say that I have heard of a "standard" to say if a gas tank is tight or not.