bad o2 sensor?

[THE REAL DEAL]

so just a bit ago, i did some logging and at idle, my o2 voltage is going around 0.00 volts to 0.05 volts at idle. the o2 trim goes all the way up to 199% at times. now it is running open downpipe but can the trim go all the way up to 199%?

 

[THE REAL DEAL]

well nevermind. i think i may know what the problem is. the damn MAS has no honeycombs at all.

 

[THE REAL DEAL]

ok so i guess it wasn't the MAS. i replaced it and the O2 trim still goes all the way to 199% at cruise and the volts at idle either sit at 0.00 or 0.05. doesn't cycle. during cruise, the voltage cycles but will go from anywhere between 0.00v to about 0.80v. I'm pretty sure this is bad but can anyone confirm?

 

[THE REAL DEAL]

anybody? beuler.........bueler?

 

[JohnCIV_Talon]

Thats defianetly a bad o2, Im surrently having the same exact problem.

 

[THE REAL DEAL]

does your idle surge? mine is doing it like mad and i think the only things i haven't done yet are clean the throttle body and replace the o2 sensor.

 

[JohnCIV_Talon]

No, my idle doesnt surge. That would probably have something to do with the tps.

 

[staticbrainwash]

TPS only reads the throttle position. Idle surge can be one of like 100 things. Check the biss, leak test, check the isc. Those are good places to start. But with how bad the o2 sounds, i bet replacing that will help A LOT.

 

[THE REAL DEAL]

well i know the o2 sensor is still bad but i think i might have found the source of the idle surge. i'm pretty sure it's the ISC. i swapped it out for a 90 ISC and the idle is steady when i unplug it but revs high and surges when it's plugged in. the old one would surge no matter if it was plugged in or not. so this weekend i'm gonna go buy a multimeter and go to the junkyard and see if i can find a good 91-94 ISC. a non-turbo one will work right? there's no turbo dsms at the junkyard i go to.

 

[staticbrainwash]

All isc's on 1g's are the same yes. If you want to make sure though, you can take yours out and take it with you and compare just to make sure.

 

[THE REAL DEAL]

so today i replaced my throttle cable, my ISC, adjusted my TPS and my idle posistion switch and the surge is gone. i'm guessing it was either the TPS was way out of adjustment or the ISC wasn't working right. my TPS was reading .4x ohms at closed throttle so i adjusted it back to .90. now i just gotta adjust my BISS and i'm gonna check my timing now that i have a steady idle.

 

[THE REAL DEAL]

ok so i followed the vfaq on setting the BISS but when i set the grounds and put the idle at 750, i take off the grounds and the idle drops down pretty low. one of my fans is running (the one that runs off the temp switch). should i unplug it and try to set the idle again?

 

[THE REAL DEAL]

unplugged the fan and it didn't make it any different. i know the ISC is good because i tested the coils. what else could be causing my idle to drop so much when i turn on the fans?