2002 Chevy Blazer, 4.3 liter 4WD, 160,000 mi. Over the course of thisweek has steadily been losing power. Feels like I have the power of a 1.5 literengine trying to push it down the road now. It does not back fire, it does notmiss, it does not run rough no matter what you do with the accelerator theengine is smooth. Power is just cut in half. On a flat road it will just doabout 60 mph floored. If you get into a hill the transmission will kick down butthe engine just does not have enough power to do much and depending on howsteep the hill I might only be able to do 20 mph. I have had several blazersover the years and never seen anything like this. All the idiot gauges aregood, oil pressure, electrical, temp. My best guess is somehow the computer hassignificantly retared the timing that I am firing way to early of TDC. Anyideas? Thanks, Ed

 

are there any engine codes on? sounds like a clogged cat or clogged pre cat, has your mileage dropped?

 

It was a clogged cat. Thanks.

 

Better figure out what caused it, converters don't just plug up on their own, (it is the result of another problem). The most common problem for converter failure, is that the fuel mixture is too rich. Could be from a misfire, or a problem with fuel delivery, etc. If you don't find and fix the problem, the new converter will clog up just like the old one did.

 

I had a similar problem with a 1999 Blazer. I was driving up a hill and unexpectedly lost all throttle. I suspected it was a catalytic converter problem (especially because I smelled sulphur), but the shop determined that it was simply a clogged fuel filter. Definitely something to check if you bought your blazer second-hand.

 

I am having a similar problem with my 02 Xtreme. No power at all. It will idle without any problem. When I drive it, the engine bogs down. Sounds like an old 4bbl under the hood with that moaning sound. Have pulled the post cat 02 sensor out and ran an endoscope in and looked at the cat. The rear section looks pristine. I have gotten OBD codes of P0101, P0301,P0420 since this happened. The cat has a rattle in it too. One guy told me that it could be the cat came apart on the inlet end and clogged up the honeycomb inside. Didn't know if anyone else has encountered this.

 

Mine turned out to be both catalytic converters were clogged.

 

Sounds like twice as many reasons to follow Captain Hook's advice in post #4 and investigate the cause.

 

To any & all,
Have a 2001 Chev Blazer LT. Was having the same issue..... step on the peddle & the vehicle was seriously lagging like it had no power. OBO II reader was giving me a MAF sensor code (mass air flow sensor). Had replaced the MAF sensor not long ago to the tune of $600.00 .cdn as per the Chev dealership's advice.
Figured out the problem last night after reading a post within the Blazer Forum here by Mobcitty.
Mobcitty went on to determine that by removing his front O2 sensor on the exhaust pipe (just under the front wheel well on either the drivers or passenger side), that the vehicles power came back to life. In conclusion, he was able to determine that the catalytic converter had plugged off. I followed the advice & discovered the same. I had the repair made much the same way he had & the little SUV is once again running like a champ. I had the preheat device & catalytic converter removed & had a gaze inside. The ceramic honey comb inside the preheat device (just ahead of the catalytic converter had failed, causing the remnants thereof to plug off the catalytic converter. Once plugged..... the vehicle became so guttless it wouldn't climb the slightest hill, nor could I step on the pedal to encourage it to move along faster for no reason.
I removed the pre-heat device entirely & replaced that part of it with a piece of pipe & went with a new catalytic converter. You will want to check with your local emissions to determine if you can get away with the same prior to doing it but I can say that it worked very well for me. SUV is running like it did when it was new! Climbed the mountain to where I live today (& tonight) with no hesitation & didn't even break a sweat. My guess is..... that, this had been the problem all along (not the MAF sensor at all & most likely not ever). I have cleared all codes with my OBO II reader & am once again back in action. Not sure entirely how true it is..... (or if it's even true at all) but according to what I have been told..... your vehicle will not run optimally if you do not clear the codes. How true that is..... I don't know, just extremely happy that the vehicle is running well again. Many, many, many thanks to Mobcitty (you are a God send)!