oxygen sensor question

[Beppe]

hey guys why does my car run great with my oxygen sensor disconnected? my car seems to be running rich. black tailpipe i don't know if this is a sign of a rich condition or not. i don't understand how the sensor can be bad its a brand new denso oxygen sensor. is there anything else that can cause a rich condition? do not really have any mods. only headers, no cat. and a catback. oh and the EGR is blocked off because i did not have the gaskets at the time. i also have trouble reaching anything over 85-90 miles an hr. my fuel pressure is about 50-54 the book states 47-49 i believe. would that little over cause it to run rich? thanks!


timing belt changed
water pump
perfectly timed
new thermostat
coolant sesnor
ect

 

[skandel11]

your car would run if it was unpluged, the car just cant tell how much oxygen is in the exhaust. how do you know that the sensor is bad? have you tested it or sumthing?

 

[heckles]

Id look into getting a new fuel pressure regulator. , that increase in psi. would definitely cause a rich condition. while the o2 is plugged in, it sends a signal to the ecm stating a rich or lean mixture. In its lean state the ecm sends a signal to add more fuel, by means of the injectors and evap system. And in its rich state the ecm in turn sends a signal to lean out the mixture. Using a volt/ohm you can test it in the car.

 

[Beppe]

well the car still ran kind of crappy so i plugged it back in. i dont think the oxygen sensor is bad because it does go into closed loop. as far as the FPR. on the 420a i believe is on the bottom of the car near the fuel filter. now if i was to get a adjustable FPR would i have to by pass the one thats already on the car? i mean what use is a adjustable FPR if one of the car is doing the job to begin with? i could be wrong though. the thing is some days the car has lots of pull and runs great. after running awhile or certain days the go gets blah. think maybe injectors can be breaking down after running so long? now i did a fuel pessure check like i said in previous post i get like 50-54 lbs. the book specs are like 47-49 now will these few lbs over make me run rich.? or am i ok? thanks