driving with cel???

[ocbaud]

ok, right now my service engine light is on because of my o/r h pipe. i have mil eliminators on the way but i'm curious about something. With the engine seeing that the cats on on there, does it actually affect performance at all?

i've heard conflicting reports on it. some people on here say that it does nothing and running with the o/r midpipe does nothing bad with the light on. others say that it causes the computer to retard timing and/or run really rich. so which is it really? and where is the evidince?

 

[sgarlic]

No, it doesn't affect your driving.

The rear o2 sensors do nothing but monitor the efficiency of the catalytic converters, and then send a "good" or "bad" back to the PCM in the form of an electrical signal. MIL eliminators simply send the "good" signal to the PCM all the time.

The front o2 sensors are what affect lean/rich conditions. The evidence is in any Ford manual, common knowledge of HO2S systems, etc.

 

[03ghoststang]

it should go rich and back off timing from what i heard that is why they always recommend getting the MIL's or shutting off the rear O2's with the tuner but never actually experienced it when i installed my O/R X-pipe but then i swapped it to a catted due to how loud it was

 

[ocbaud]

see what i mean??
different reports

 

[sgarlic]

see what i mean??
different reports

Different reports, but he's wrong, and I'm right.

Here's a good read: http://v8sho.com/SHO/TSB0197HO2SServiceTips.htm

Note the difference in names. Upstream = fuel sysetm monitor , downstream = catalyst monitor