[V8] The continuing saga of the check engine light (93 4.2)

[Buchholz, Steven]

There is little doubt that an OXS is one of the possible culprits for causing the "outside control parameters" code ... But it is not the only one.  If you have one or more cylinders misfiring it can create exhaust that the OXS will indicate as being too rich ... As mentioned before the fuel pressure regulator is another candidate.  I usually recommend against shot-gunning the problem ... Take the message as the ECU telling you that you need to give the engine a good once over ... Pull the plugs to see if you have any indications of misfire ... Check the dizzy caps and rotors ... All the old stand by tune up items ... 

Steve B
San José, CA (USA)
> 
> that sound EXACTLY like mine about 2 weeks ago. replaced the 
> o2 sensor, been fine every since.
> mine was also smoking heavily when cold (bluish grey) that 
> has also stopped. I wired in an o2 sensor for a 88 ford tarus 3.0.
> 
> --- Carter Johnson <carterjohnson3 at yahoo.com> wrote:
> 
> > So, after blindly assuming that the check engine light had 
> something 
> > to do with the oil level, that appears to be more of a coincidence 
> > than anything else - a strange coincidence, but a 
> coincidence none the 
> > less.  The light was back on in force today as milage once again 
> > plummeted into the teens despite a recent oil change and 
> full level.  
> > SOOOOOOO
> >    
> >   Off to the mechanic.  Checked the code - oxygen sensor regulator, 
> > and oxygen sensor out of maximum adjustment (or something to that 
> > effect...).  Mech thinks full pressure regulator sticking open, 
> > causing enrichment and oxygen sensor unable to cope.  Ok, 
> intake comes 
> > off and waaaaalaaaaaaa - one of the problems - the return  
> fuel line 
> > is leaking (driver's back to passenger bank, the lower 
> hose).  So we pull all that appart and test the fuel pressure 
> - dead on 50.5lbs at idle, 58-59 at WOT.  Ok, so that's in 
> spec.  Replace the line, and light goes off.
> >  It's stayed off for the time being, but he's pretty sure 
> that leaking 
> > line was NOT the cause of the CEL.
> >    
> >   Stumped again.  Still thinking O2 sensor?  Why am I smelling raw 
> > fuel prior to the light coming on then, and the sensor is 
> attempting to correct the problem?