Hi all,

My 96 4Runner was sitting on the driveway since last November, so about 10 month. I started it once in a while. It had full tank of gas with stabilizer in it.
I put it back on the road yesterday, but it failed emission test (exhaust pipe probe) both in idle and 2500 RPM.
After the test I drove it some more and check engine (CEL) came on.
I used to have P0442 (evap) for years, but this time it was also P0171.
I took out MAF sensor and cleaned with CRC MAF cleaner spray.
Changed air filter.
Dried, put it back, CEL comes on again after 10 miles - P0171.
My MAF is 22250-20020 like a Camry one


Any ideas?

I planned to siphon old gas, but it proved impossible.

 

Check for vacuum leaks. Check your fuel trim readings and MAF reading. If the fuel is in bad shape, it could cause a P0171

 

for the benefit of future generations
problem solved by replacing front O2 sensor, it was dangling out of the pipe as the nuts have completely corroded, the same thing happened to the rear 02 sensor more than 5 years ago.