I've gone through all the obvious stuff and am still getting these codes.

I warmed up the car, then cleared the codes, then drove it for 10 miles. Never once did my short term fuel trims go below -8, but still after 10 miles it threw the rich codes again.

When the car is cold, the short term trims are really negative (-30). Once it warms up the trims are negative, but just a few points. Temp never gets hotter than 185, but it is wintertime.

Plugs aren't awful, but do seem to indicate it actually is rich (as opposed to only *thinking* it's rich). Fuel rail pressure is 45psi consistent. Vacuum is -18 at idle, -22 at 2500rpms. No vacuum leaks I can find.

I've gotta get this MIL off so I can pass emissions. Here are the results of my scan tool when at idle warmed up.

STFT1 +0.8
STFT2 -2.3
LTFT1 -4.7
LTFT2 -2.3
MAP 4.08
RPM 672
TIMING 9.0
AIRTEMP: 72
TMP 176
MAF: 0.66
TPS 0.8
O2-1voltage: 0.46
O2-2voltage: 0.44

Do not know how to diagnose and/or exonerate the evap solenoid, clogged exhaust, or some of the other possible causes, so all advice is desperately welcome.

Thanks!

 

What year/Model?
Mileage?

Try cleaning MAF sensor with MAF cleaner with cold engine.

Ever replaced 02 sensors? What's the voltage swing on the front ones?
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Also, please list the "obvious things" you've already checked so no one wastes time suggesting things you've already done.

Thanks.

 

Read about the ETCS posted in this forum.