O2 sensor problems, when will rich mixtures ruin a cat?

Ryanm07 · Post by **Ryanm07** » Wed Mar 28, 2007 7:33 pm

Ok I had a thread about this in the forced induction forum, but I got some more info and figured it pertains more to the car in general then the turbo system. with that being said...

When I plug in my sensors they throw "shorted to voltage" codes and the car reads rich, and tries to lean it out until the car stalls, unplugged the car runs fine (for not having o2 sensors). I tried new sensors, and checked the wiring. I brought it in this week to get a custom downpipe made with a magnaflow high flow cat, and to get the sensors figured out. They made the pipe but in the end couldnt fix the sensors. The mechanic told me he thinks the sensor is too sensitive and to try an "old style" sensor which made no sense to me, because noone else has this problem and it doesnt bounce around, it goes to high voltage and stays. I'm leaning towards a short in the PCM somewhere, I have a new one already but I need to get it flashed. Does this sound like a PCM problem? or is it possible another sensor, or anything but the sensor or wiring could cause this problem? And now that I have a cat on my car and no O2 sensors how easy is it to destroy it from rich fuel mixtures?

Thanks Guys!!! any help is GREATLY appeciated, this is 8 months i've been at this.

ragek23 · Post by **ragek23** » Wed Mar 28, 2007 8:16 pm

If you solve this problem you will be my HERO! I have the exact same problem! Paid the dealer close to $600 in labor costs before they gave up.

I am thinking this problem may be caused by a faulty rad. relay? or maybe a short in the engine heater? I all know is many are baffled about this problem.

Ryanm07 · Post by **Ryanm07** » Wed Mar 28, 2007 11:39 pm

That sucks...I felt better about it when I was the only one with the problem. rad. relay? engine heater? what would those have to do with an O2 sensor? the wires goto the automatic shut down relay, heater relay, ground, and signal. and the code i get is basically saying that its shorting out somewhere, if its not one of those wires it has to be the PCM right? i dont see what else it could be besides the sensors, wiring, or PCM. is there anything else it could be?

kc2005ptgt · Post by **kc2005ptgt** » Thu Mar 29, 2007 12:40 am

with your 01, you could go look for a backup pcm from a junkyard and try that, only way to find out without spending mucho skrilla...
I personally would be checking some wires, could be that the extra heat from the turbo could have "burnt" some wires??? maybe... wouldnt hurt to look!

ragek23 · Post by **ragek23** » Thu Mar 29, 2007 8:40 pm

Ryanm07- have you had any luck?

this week i should be getting my 02 sensor so if that doesn't work ( idont' think it will) i am going under the car and checking the harnesses for both o2 sensors. next step after that is getting new realays since i don't have a ohm meter up here.

Ryanm07 · Post by **Ryanm07** » Thu Mar 29, 2007 11:06 pm

no since i got it from the shop i havent had any time. i'm running with a downstream now and no upstream and i havent even had time to see if the downstream threw the code. I have a junkyard PCM, but I have to spend the $97 to get it flashed for my VIN. now maybe we can find something in common here. have you "messed, fiddled, or upgraded" anything lately? lol. Before the turbo set-up mine was fine. immediatley afterwards is when it started happening. electronically, this is what I touched:

Upstream O2 sensor- put a new one in
Downstream O2 sensor- Tried an eliminator
Injectors-Put new accell 30lb. injectors in with new harnesses
Map sensor-wired in my map clamp so my computer wont see boost.
Fuel pump-put in a walboro 255lph and did the "spoolboy" mod.

Now you mentioned you blew $600 at the dealer? I was going to bring mine there but i have a feeling i'll get the same results. Now what did they do? Did they look into it being a bad PCM? Let me know man, I know your feeling my pain lol. And theres only so many things this could be, i'm sure we can figure it out together.

especially let me know about that fuel pump lol. It may have even been right after that when my problem started happening.

ragek23 · Post by **ragek23** » Thu Mar 29, 2007 11:38 pm

OK here is what happened:
installed obx header with downpipe (nocat)
no sensors were thrown (even the no cat code was not thrown) and everything was working great.

i wanted the cat back in and when i reinstallled it but, there was not enough clearence between the heat sheild and cat for the downflow. although i thought there was (atfirst) and the wires got cut and shorted.
result of short:
auto shut down realay and autoshutdown fuse blew. (had to get towed)
horn relay was also blown (used as temp fix to go to autoparts store for another but they were out and i broke down)

since then:
horn and autoshutoff relay have been replaced, fuses checked and replaced, downflow has been replaced.

car dies now if i connect the upflow sensor. As a result the engine heater is on all the time and the car runs very rich.

ragek23 · Post by **ragek23** » Fri Mar 30, 2007 7:48 pm

new 02 sensor did not help at all i guess its time to wait and see if a new pcm will do the trick

Ryanm07 · Post by **Ryanm07** » Sat Mar 31, 2007 6:50 pm

I have had no time at all to even call the dealer, and its too late now. i'll call monday and maybe get them to do it tuesday or something. idk i'll call them and see what they say. i'm hoping I wont have to leave the car there, i can just unhook the old one, flip the connectors and plug in the new one for them to flash it through the OBD port, then plug in my old one to go home and then just install it at my house.

Ryanm07 · Post by **Ryanm07** » Mon Apr 02, 2007 6:41 pm

called the dealer today. The guy basically told me if none of the wires are touching then its definetly the PCM. He also told me that on my 01 that junkyard computer that I got should just go right in without being flashed, thats something i'm going to look into because when i tried it the car didnt start and I was told otherwise by another dealer.