This is topic can i pass obd2 with no upstream o2 sensors? in forum Tech Talk at Northern California Ford Owners  .


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Posted by Michaelmurch (Member # 12921) on :
 
i have a 2002 mustang gt with long tube headers and bbk high flow cats on an aftermarket h pipe and there are only 02 sensors after the cats!
anyways the smog guy i went to passed me for visual so with that out of the way i thought i would surely pass but my nox was high on the low speed! about 1050 and the max is 415 or something... the high speed was like 403 and max is 407 so that was close as hell too.

i had 87 octane in the car though, will that affect it?
and also because of the o2 sensors the check engine light comes on so i turned it off right before i got there and that tripped it too. i know the engine adjusts some parameters whenever you reset the computer so could the incomplete obd2 cycle be to blame for these ridiculous numbers along with the gas?
will mil delete wires fix this?
is there a window of time where the obd2 diagnostics is complete before my check engine light comes back on? i think the guy i got it from (who i cant ask anything) reset the computer and smogged it before the cel came on and after the obd2 had cycled but is there even a window of time where this is possible??
another smog guy says the egr valve wont make the nox that high and that there is no way to have the cel off and the cycle complete but it takes a long time to come back when i clear it usually..
help is appreciated lets keep these modded stangs on the road guys!
 
Posted by Wht86drop (Member # 12104) on :
 
Get mil eliminators, run 100 octane and run the drive cycle monitors. If that doesnt work you might have to do more obviously. The car wont pass if the readiness status monitors arent all ready.
 
Posted by Secnd2nun64 (Member # 1431) on :
 
Just go to an exhaust shop and have them weld in some o2 bungs into the headers. Cost you probably $40.

Also when you reset a computer it does take time for all the systems come back online and when they do the CEL will come back on. Smog machines now know when the systems are not running so just resetting the computer or pulling the CEL light out of the dash won't help you.

I'd get the o2 sensors put in and pull the CEL codes and see what else is wrong.

[ 2013-05-23, 06:09 AM: Message edited by: Secnd2nun64 ]
 
Posted by SacStangDriver (Member # 8304) on :
 
i dont know why you would run an obd2 car without the precat 02's those matter the most. the 02's help with fuel control.

[ 2013-05-23, 10:03 AM: Message edited by: SacStangDriver ]
 




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