I had my muffler shop install a Magnarflow hi flow cat to go with my Magnaflow muffler. Three days later the service engine soon light came on. The Blazer is running great! You can feel a lot more pressure at the exhaust tip. I don't have a scanner available to me for any codes at the moment. I have two O2 sensors one before and one after. The one before is three months old the one after I have no idea, the car has 160000 miles. Any ideas?

 

i'll guarantee you its a low catalytic converter efficiency code---the aftermarket cat changes what the sensor sees---it wont change how the truck runs at all, that o2 sensor just tells you if the cat is working.

you can get an O2 simulator, put a black piece of tape over the CEL light, or you can kill two birds with one stone---have your PCM performance tuned and have the post cat O2 sensor program deleted.

Im in the process of having the latter done----id say 30hp and 2-4mpg and getting rid of the CEL is worth 190 bucks canadian [8D]

 

If you woudn't mind, can you give me the contact info?

 

pcmforless.com

We have emissions test here in NY. If they are required for you, I would ask if it would pass the sniffer test. (fool the computer.)

 

I installed the O2 simulator and disconnected the battery for ten minutes. service engine soon light is now off and the truck runs even smoother. The wiring color codes did not match the instructions, I had to use my voltmeter and schematic from my haynes manual to veriy proper connections.

 

so whereabouts did you pick up your 02 sim from? got my tuned pcm in the other day--and it seems i have a code again--my friends down at my muffler shop are going to read the code tomorrow and if its the same code, then it will be cheaper for me to buy an 02 sim that it would be to ship it back to my tuner. (unless they admit they messed up and pay for everything)

[:@]--definetly loving the more-power-isticity though lol! and the lack of a speed governor, torque management, and firmer shifts are REALLY nice too! (burnouts=easier [:-])

 

Sorry for the delay, but work got busy this week! OK, after about three days and using the Blazer about six times the Service engine soon light came back on. This time the engine still idles and runs well. I called PCM for less to send in the PCM but the guy (forgot his name) said the 95 Blazer PCMs cannot be programmed. He said that for some unknown reason the software they use won't work on that year only so I'm screwed. Now he did say that I should still be able to run in closed loop.
Now for your question I bought the O2 simulator at WWW.o2sim.com. This weekend I'm gonna try to solder my connections and see if this helps I used a crimping tool and butt connectors. I figure were only sending Milivolts so any connection problem could make a difference. I let you know midway into nextweek if this helped before you buy yours.

Oh. can anybody confirm the wiring? My harness to the O2 sensor has four wires: Purple, pinkish/ red, tan and black. I connected the O2 sim power to the pink one because it was the only one with 12 volts with the ignition on. I connected the signal wire to the purple one. The ground is were I was confused, both the black and tan had continuity to chasis ground so I just picked the tan one.

 

Your '95 has an OBD1.5 pcm which is why no one can modify it. It's not OBD1 and it sure as heck isn't OBD2. It's thought of the bastard child of OBD1 & OBD2.

As far as your wiring:

That's out of one of my references for a '95... The tan wire is probably the same as the black wire shown above. And it's also possible that black w/ white tracer is just black. They are the grounds, but you may want them to be wired in properly.

 

OK guys I swapped the ground connection from tan to black on Saturday, disconnected battery for ten minutes. I have used my Blazer everyday since then and no more light. Monday I most have turned the car off and on seven times. Yeah my wife now has me store hopping looking for a new stove! LOL So I think the simulator is doing it's job and the truck runs and sounds great.

One more thing, I was jogging the other day (trying to get rid of beer belly) and saw a Blazer with dual exaust. I thought it couldn't be done without a lift kit. I'm gonna go over there with my camera and see if they let me take pictures.