2002 Ford E450 - S/D O2 Readiness Monitor

[Tim Martin]

This 2002 E450 S/D with a V10 and 178,000 miles on it has an intermittant miss.

I noticed also that the O2 Readiness Monitor is not reset. Yet, when I read Mode 6 results, the O2s are working fine. My question is after having driven this thing for hundreds of miles since PCM code clear, what is keeping the O2 Readiness Monitor from resetting? Is the issue partly due to an intermittant miss? The PCM is not picking up the miss. Not even a pending code.

What am I missing? It has new plugs, boots, coils, and filters and was sent here by another shop for diagnosis.

[steven kiser]

the very first thing i look at in situations like this is operating temperature. a little not i read here, on this application there are two different sensors used. they read at different levels. if they are interchanged the system will not function. it's not an upstream downstream issue it's a reading issue. there is a specific drive cycle we follow to reset fords. these need a cold soak. you just can't hop in and drive it. if it's been driven, i think you do a koeo and a koer test. this will bypass the cold soak timer. there is a specific road test to trigger the misfire monitor, it doesn't automatically monitor. if you need it let me know and i'll get it to you.

[Tim Martin]

Steve, for the most part I understand what you are saying about drive cycles. I have that info. The matter of temperature sensors I am not following totally. Yes, they do have coolant temp sensors, cylinder head sensors, and intake air temp sensors. Which ones do you have in mind?

[steven kiser]

coolant.

[ricmorin]

You can bypass the cold soak timer by cycling the key on the off, then on again. Leave on and install scanner and set up. Start engine from key on and let idle 15 seconds. Drive 40 mph until the coolant reaches 170F. Make sure the IAT is between 40 and 100F. Then cruise at 40mph for at least 5 minutes. That is supposed to set the o2's.

Some vehicles are real finicky. I have a V10 and I can unplug an injector and it won't set a misfire for quite a long time.