Okay so recently we bought an '03 blazer ls-4wd-vortec 158xxx miles all around we were so excited! It was bought at an auction..as is.. the day we paid for it the rear end went out on the way home. That was fixed a few days later, as soon as the rear end was put on they were test driving it, did not make it far! The converter was actually glowing red which shut off the truck.. back to square one.. so far we have replaced : distributor and cap (cap twice once by us once by the shop) , rotors & rear end, spark plug and wires, MAP sensor. And (sorry if i get this wrong) some type of spider gear injector kit/system and your basic fluid flushes. It was taken to a local shop to get the timing reset and there was a misfire on cylinder 3. When i picked up the truck it seemed to be running okay other then it needs an alignment. HOWEVER, yesterday *it has been out of the shop for 5 days* it started sputtering again, lag in peddle, slow acceleration and a noise coming from what might be the converter or muffler, i can only describe it as a ''put put, puff puff'' noise. Check engine light is back on and it still is throwing all the codes of the parts that were replaced plus the mass airflow sensor.. We disconnected the sensor and drove it for a little bit.. drove amazing.. until it reached its normal running temp and we hear the put put noise again with the rough idle .. advice of any kind would be amazing. So far the only thing we can think of is clogged cat from it getting so hot and the Maf sensor..?

Okay sorry let me clear up a few things, After the rear end was replaced our 'family mechanic' and my husband were test driving it ((that is when the cat was red)) it was towed back to the house where the guys found out that the other things were wrong. It was taken to the shop ONLY to get the timing set when THEY figured out there about the misfire on cylinder 3. There is no code for the cat only for a mass air flow sensor, what i wanted to know is if this sensor could be causing all of these problems

 

You should be able to return to the shop to get them to give you the codes it is throwing now for free if it is not running well 5 days after they gave it back to you. If not go seek another well recommended shop. Report the codes here. Having all the codes will get you the best advice.
If your cat was smoking and glowing you will be needing a new one. One of the codes will probably be for the cat. Go with the OE direct fit replacement parts. They cost more but it makes it easier to work on the car. Nothing worse than a weld when you need the exhaust pipes to come apart.

 

Wow yea thats alot of stuff, sounds like at least what you paid at auction. Its strange that after they saw the cat they did'nt want to replace that straight away.

Maybe they cracked open the plenum they saw a badly leaking spider and assumed that was the problem, they will clogg the cat with tons of unburned fuel.

You can post up the codes your getting in the order they were set, the first one set is sometimes a clue to the problem as the others will cascade from there.

Your already in for a ton of money so my bet would be a new cat oem or universal, don't think it matters much right now, watever is cheaper. I don't see that you did the cat already, did you?

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Just looked up at 33's he is correct, stick with an OE direct, mine is so old I just don't care

The cats get that cherry red when they are clogged and will cause the problems you disscribe from backpressure.

Giving your mech the benofthedoubt on doing injectors first. You might want to find a new guy.

Sorry about the rear, it happens.

Good Luck and let us know how its going. Post the codes if you have them, not sure if they will mean too much since so much has been messed with.

None of the stuff you have done is out of the ordinary at 158 if the thing was never touched. Would guess no one ever stuck there finger in the rear diff to see if there was any oil.

You get it squard away and you will have a nice truck.

 

A glowing converter is a symptom, not the cause of the problem. It will probably need replacement but, what ever is causing the rich fuel mixture needs to be repaired before replacing the converter, or it will damage the new one.

Check fuel pressure and leakdown first. Most auto parts stores rent/sell/loan the tester. Let us know when you have one handy and we can explain how to use it, (very simple).

 

Okay sorry let me clear up a few things, After the rear end was replaced our 'family mechanic' and my husband were test driving it ((that is when the cat was red)) it was towed back to the house where the guys found out that the other things were wrong. It was taken to the shop ONLY to get the timing set when THEY figured out there about the misfire on cylinder 3. There is no code for the cat only for a mass air flow sensor, what i wanted to know is if this sensor could be causing all of these problems

 

A bad MAF could cause the rich mixture, but not a misfire on only one cylinder, it would affect all cylinders. If the MAF is bad enough to cause the converter to overheat, it will set a code and turn the SES light on.

 

Check for a vacuum leak or air entering the system after the MAF sensor in the plenum. Either of these will cause a MAF code. I swear the poor MAF sensor is one of the most misdiagnosed part out there. Next to O2 sensor

 

The converter does not over hear, it did once before we replaced some things

 

Mine did the same thing hose on the PVC vavle was cracked replaced it and problem solved hope yours is that easy