o2 gone bad

[eric27]

does a bad o2 make that side run rich? been having bad mpg. and replaced almost everything.........what type of drivability problems would a bad o2 bring? im getting codes 998, 116, 159. :thumbdwn: any help would be greatly appreciated

 

[MrShorty]

Was the 116 a KOEO code (see my "notes on pulling EEC-IV codes" thread in the EEC-IV forum if you don't know how to distinguish KOEO from CM codes)? KOEO 116 is most often a result of running the KOEO test on a cold engine.

Was the 159 a KOEO code? While a bad O2 sensor can cause the engine to run rich, it rarely will trigger the 998 code. More often it seems that an MAF code accompanying the 998 points to something wrong with the MAF or the MAF circuit.

 

[eric27]

i thought it may be the wires also. and thanks for the info about the cold test. guess i was doing that. i bought the truck for 1200 with problems. got it running great for a week. then started having different problems. currently i have over 1300 hundred in parts....is it normal to have 6 volts at the iac harness with koeo? the hard fault is what gets me too??? with the maf unplugged i get 11 mpg,but runs good. plugged in i get 8 mpg and the drivers side plugs get all black....also major black soot from exhast. new parts all aruond. only parts not new are....the drivers side o2 and computer in the passanger kick panel.........but the 6 volts???? is that from the comp or from a short?

 

[MrShorty]

is it normal to have 6 volts at the iac harness with koeo?

I'm not sure. I know the fuel pump circuit likes to show about 6 V when the pump isn't running, which seems to be a "ghost" voltage that comes from the PCM. Perhaps the IAC is the same.

 

[Iron Weasel]

VPWR (Red wire) between the IAC solenoid harness and battery ground should be 10.5v or higher Key On, Engine Off.

Key On, Engine Running the operating range is from 3 - 11.5 volts @ 3000 RPM.

 

[eric27]

so check wireharness then ecc? i looked at the ecc and seen a very small amount or corrision. could that cause the 6 v? thanks ill look into the harness more hopefully its just an open wire. wishful thinkin ill keep you posted

 

[eric27]

....cat on.....and purrs like a kitten. didnt think it could be that quiet. almost cranked it when it was on already.....but the bad gas and mileage continue. update now is new catalytic converter, koer code 159. and a new one 157. koeo codes 998? hard code? whats that. . . . it didnt show on the koeo. also checked referance voltage at iac and maf( both brand new)(2nd brand new maf, warranty) both had 10.7 koeo.........im left clueless. only parts i havent got new are one o2(still) and the ecc..... guess next step is the o2?