Please help me! All kinds of problems!

[ff_jeff]

plugged cat or slow 02s probably.

just replace the o2's. mine was very similar, and new o2 fixed prob.

[408.Luke]

ive been told to replace my o2's 2 times (lean 02 code) and i havent once done it. it took me a while to find the problem but what it was is i had a leak in my exhaust manifold gasket off cylinder 7 so it was pulling fresh air into the exhaust before the o2 sensor making it read lean and the truck started dumping in alot of fuel and making it smell like it was running rich so if u havent do a quick check for a leak some where, if ur trucks loud u might not have hear it

[GasGuzzler]

update

my fuel trim bank 1 is reading -20, which is rich, and my fuel trim bank 2 is reading +3, which is lean.. Why such a big difference from the right and left side of the engine? Also, my EVAP purge solenoid is always always always venting. This is wierd! Because i thought that the evap system was only supposed to purge while you are running down the highway at high engine speeds. also i accelerated the engine a small amount at a time, like 500 rpm every 10 seconds and the fuel trim on both sides eventually evens out at about -15, which is still rich. This kills my gas mileage seriously. i used to get about 16 and now i get 11, easin around on it.. no WOT's for me hardly ever. if i do happen to floor it and it shifts into first my mpg drops to about 9 for maybe 20 minutes afterwards then it goes back to normal. so anybody that can help with this please reply. i have a feeling its a vaccuum leak.

There are a lot of technical issues with the post and I hope NITROUS comes along and explains the stuff I miss but....

First, are you talking long term FT or short? If short, forget it. If long, forget about +3 (or -3) fuel trim. Some of these things run perfectly at or above +/-10. It's when you get past the mid teens either way that there could be an issue. The PCM has the ability to adjust so the +/-10 is nothing.

-20 is an issue if LTFT is what you're talking about. If you have cats it is pretty likely the LH (driver side) cat is dying. Then again, since LT and ST fuel trims are averaged per bank, you could have one almost inoperable injector causing a lean condition that is being covered up by enrichment, a leaking fuel pressure regulator (depending on the year) a fualty B1O2S1...anything that is specific to Bank1.

The EVAP purge solenoid never vents...even on a malfunctioning system. You may have the purge solenoid and the vent solenoid confused. The PC is on the intake manifold, the VS is underneath near the fuel tank. IF the PS was stuck open you'd have a huge vacuum leak and very lean FT's on both banks. If the PS was stuck closed you'd only have an SES light. If the VS was stuck open you'd only have a SES light. If the VS was stuck closed you'd have an SES light, fuel smell, and hard to fill tank situation.

The fact the trims change at higher but nearly steady RPM means something but the data you've supplied is a little confusing. What scanner/system are you using to retrieve DTC's and trims? -20 aught to set a DTC (+/-17% in many cases and +/-25% is max)....

[devin_deville]

I use the genesis scan tool.. and it is the vent solenoid, sorry typo. i did a crankshaft relearn, and all the rich codes went away for a little while, but then they came back

[devin_deville]

and yes i am talking about ltft

[devin_deville]

a fualty B1O2S1...anything that is specific to Bank1.

what is B1O2S1??

[GasGuzzler]

Bank 1 Oxygen Sensor 1.

Beg, borrow, or steal (not that option please) a Kent-Moore exhaust backpressure gauge and test both converters.

[devin_deville]

okay. i think im gonna buy some new o2 sensors tommorrow.

[devin_deville]

what psi should the backpressure read?

[GasGuzzler]

Less than 1.5" of Hg in front of the converters at idle and less than 2" at 2500 RPM.