cruise stumble and goofy O2 numbers

[granitestategn]

Where to start? Worked on my car Saturday and it was running pretty strong. Washed it, waxed it. Degreased the engine bay. Hosed the crap out of the engine bay. Drove it around some to dry it out. Took a couple of WOT blasts to make sure I was ready to go to the track Wed eve to see what it will run. Get home from work. Start it up and it starts smoking pretty bad, running super rich. I check the O2 on my scanmaster and they're around 900+. Pull out of the garage and it's still rich and running rough. I drive down the street and check the cc # on scanmaster and they aren't moving. This is a heated Ford O2 sensor. Almost new from Kirban's. I drive to my buddy's house and it never goes into closed loop. O2's are all over high, low, normal. Never sets a code, either. Still running rough. O2's at WOT are not bad, high 700's, low 800's, no KR. Just doesn't have the get up'n go. I take out the new heated sensor and put in my OEM original sensor w/96K on it w/ broken housing and it runs the same. Sometimes the O2 just drops out to 0. Still never set a code. Go to Autozone and buy a new Bosch (I know, they suck) sensor and put it in. Still runs the same. O2's drop out, cc# stops scrolling. With the new sensor it was VERY active at first, then slowed down considerably. At cruise with the throttle steady, the O2's bounce all over, sometimes down to 0 then back up. O2 sensors had a lot of soot on them when removed (way rich). Oh yeh, my block learn is hanging around 105. Integrator is all over. I'm not sure where to start. Vacuum leak? EGR? Broken O2 sensor wire? Screwed up something by getting it too wet? I'm disappointed because I've been working on this car for a couple months and I wanna go to the track. First the brake problem (converted to vacuum), now this. Instead of going to the track we went to a local cruise night. A couple nice cars there. New Mustang SVT Cobra w/ the supercharger. I asked the dude what it's supposed to run. He said ~12.3. I wanted to be able to tell him what the GN would run but I don't know yet. Kind of embarrassing. Nice GSX there, too. I'm bummin'

 

[granitestategn]

Anybody?

 

[blackbuick87]

With a Thrasher chip it will read zero for a couple seconds at a time sometimes when you let off the gas.

I would look at the wiring for the heated O2, I think you may have done something when you "hosed the crap out of it"

Also maybe you got the water in between the coilpack and ignition module if the gasket has a tear in it.

Try unplugging your ECM and clearing out the computer, maybe try a different chip?

Also what does your MAF sensor read? Give it a whack, though I have seen it suggested a lot and never seen that work personally

 

[granitestategn]

Thanks for the reply Blackbuick87. I'll go home and bi***slap the MAF a couple times and see if it helps. It ought to at least feel good. My O2 readings were dropping to 0 at cruise with steady throttle. The odd thing is that it ran fine Saturday night after hosing it down. Four days later it screwed up. I unplugged the heated O2 sensor and it has the new bosch unheated one installed now. I just taped up the heated O2 sensor plug and left it hangin. I'll look around for an issue with the coilpack. Could the IAC be screwing up?

 

[granitestategn]

Problem found.

Just in case someone digs this thread up in the archives. The problem was that I didn't remove the old o-ring that was stuck in the fuel rail when I changed fuel pressure regulators. A piece of the o-ring broke free and plugged the fuel return line. This made the fuel pressure jump to 80 PSI because the regulator couldn't relieve the excess pressure. 80 PSI, running rich...DUH! Just a coincedence that it happened when it did.

 

[Jimn8or]

This is why I always ask "What's the very last thing you did to your car?" before posting a reply to a 'gremlin' case...Rarely is it related to the info provided by the poster and the recent work is almost always kept a secret...Glad to hear you got your problem solved. Funny how it all fits together huh? Rich as hell, O2 sensors make no difference, BLM's wrong etc... piece of crap stuck in the return line creating 80psi
Have fun at the track and remember that the time given by the Poontang owner is one he's never actually run. I've had fun eating one of those in street trim up here and the look on his face when you tell him it's a six...well as Master Card says "Priceless"
Jim