Ok so lil while back i was have major issues with the truck not starting and running really rough and went through a couple of parts first i went through some EGR electrical components and then i replaced the o2 sensor till no luck and i was pulling a running too lean code and egr insufficent flow code then i replaced fuel pump and that did the trick but now i pull a running to rich and insufficent egr flow .. would running the the new o2 sensor while it was running lean and rough damaged it enough to misread ?

a 300-i6 should be getting better the 8.5 MPG even with the 39.5s

any suggestions, advice, or answers will be appreciated thanks

 

i dont know what kind of gas mileage your lookin for with 39.5s but even running good it shouldt get much better than that the 300 is a pig great motor but loves that fuel as for the o2 sensor its telling you that the motor is running rich so its doing its job check your plugs and they will tell you if your running lean or rich or what not

you said you replaced EGR electrical components but did you replace the EGR vavle

 

i got 14-16 mpgs with my I-6

 

before i was having fuel pump issues i was getting 12-13 with 39.5s ... and no i havent replaced egr valve ill check plugs tomora

 

have u recalibrated ur speedo? 12-13 with 39.5s, stock gearing and a 300 is comical. 8.5 sounds right.

running rich could be a bad fuel pressure regulator, plug/wires/cap/rotor. check rail pressure. could also be a stuck injector open.

egr flow tells us either the egr is stuck open or the sensor is kaddywompas. did u test the EVP before replacing?

what exact codes are u getting? im just throwing out some things, if i had the exact codes i could help a little more.

 

If you are indeed running rich, check your fuel pressure at the rail. If the pressure is higher than 39 psi without vacuum, you may have a bad fuel pressure regulator. Running rich is symptomatic of a bad regulator. If that is the problem, make sure you change you oil and the O2 sensor when the regulator is replaced.

 

nope, the 300 runs at 45-60 psi of fuel pressure.

 

it might sound comical but i aint jokin i was gettin around 11-12 miles to the gallon i did all the math and i will pull exact codes again when i find my reader.....if it was running rich wouldnt i be getting some kind of smoke out the tailpipes or smell gas occasionally ...because i dont and yes EVP was bad when replaced

 

there amazing, with those big swampers.

i would do a hard reset (disconnect the neg battery cable for 15 minutes to clean memory) and drive it until a code comes up.

but to answer the Q about the O2 sensor, no it shouldnt hurt anything. There is a crystal inside that determines lean/rich and overtime they just wear out. and yes u should have a raw gas smell or a sulfer (rotten eggs) smell if it was running rich.

 

There is no smell

 

ok pulled codes finally

173-HEGO (HO2S) sensor fault/rich

179-HEGO (HO2S) sensor fault unable to switch/ rich during part throttle

332-Insufficient EGR flow detected