I'm trying to figure out why my wife's Blazer is running terribly when it gets hot. 98 s-10 Blazer, 4X4, 4.3 Auto. I have a scanner and think one of my O2 sensors is whacked, but I just replaced both of them 6-mos ago. Here's the issue: runs fine for the first 20 minutes or so, plenty of power with no issues. After 20 mins, when coming to a stop (in drive) it misses like crazy at idle, stumbles and shakes, smells horrible and lacks power on acceleration. Once up to speed you can't really feel anything wrong, just lacks power. I ran a scan on it this morning and recorded the info while at idle, in drive, here's what I got:
Closed loop - Yes
Load Value = 3.9%
Coolant Temp = 192
MAP = 151 in. hg
RPM = 555 - 619
IAT = 96 deg (it was 58 deg outside?)
TPS = 0
OXY SENS 1 = 0.040 - 0.095
OXY SENS 3 = 0.890 - 0.905
OXY Sens Bank 2 = 0.065 - 0.810
Front O2 Sensor = 0.034v
Rear O2 Sensor = 0.890v
EGR = 0.68v
EGR Duty Cycle = 0
Total Misfires = 38912
Cyl 1 - 2567
Cyl 2 - 14
Cyl 3 - 1947
Cyl 4 - 1
Cyl 5 - 2001
Cyl 6 - 0

I bumped the RPM up 50 just to bandaid it until I can figure it out. The CAT doesn't get red hot and no signs of performance loss when cold.

I'm chasing my tail here, I've recently replaced the cap, rotor, wires, plugs, distributor (cap mounts broke), both 02 sensors (6-mos ago). It's not throwing any codes anymore, but power is down (once it gets hot after about 15 mins of driving) and exhaust stinks bad along with a really rough idle.

If you have any ideas, I'm open to trying something else before I take it to a shop. Thanks in advance!
Magman

 

Oh, forgot to mention there is no SES light and it is not popping any codes.

 

Have you checked your cat?

 

No, I haven't checked the CAT. How do you go about doing so? Remove it? I think if i'm going to go through the trouble of removing it, I may as well replace it. I sure hope it's a bolt-on, direct swap, that would be nice. I haven't done a lot of work on the Blazer, it's been a great vehicle with relatively low maintenance for the most part. It's approaching 150,000 miles now and runs great until it gets hot!

Any other ideas? I'm going to go price check a CAT...

 

Whoa! That CAT is expensive...$234.99 at NAPA, $262.99 at Schucks. Ouch! I'm going to have to do some looking around. Anyone know of a place online to get a good quality, cheaper CAT that's a direct fit?

 

Yeah, if the cat is your problem it's not extremely cheap to replace but that sounds about right on the price.

As for how to replace it try checking out this video.
http://www.youtube.com/watch?v=ULP-W...eature=related