Bad CAT?

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2005 Chevy Trailblazer inline 6 cyl. Gutless, accelerates like the putt putt cars at disneyland. In park or neutral, WOT gets 3500 RPM and no more. Runs smooth, not missing. I would say this has been coming on slowly, changed the plugs about three weeks ago due to my wifes complaint that it felt sluggish. Now it is terrible. Could this be a plugged catalytic converter? What else should I check, or since it has to be effecting emmisions just take it to the dealer for warantee? Is the "New GM" honoring emissions warrantees from the "old GM". Almost forgot...MIL is off and no codes are stored.
 
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Is the cat glowing? If it is causing that sort of back pressure it should be getting VERY hot. Oh, Park and Neutral rev-limits are lower than in gear. 3000 to 4000 RPM P-N limit is common. Our Montana limits at about 4000. I think my vic limits at about 3000. Honoring the emissions warranty is federally mandated. I had a cat replaced on my Vic awhile ago. Nobody at the counter knew about it, they just wanted to charge me $1500. I had to go down there and smack them around a bit with a rotten fish. They complied.
 
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Do a back pressure test using a back pressure gauge.Most parts stores sell them and you put in place of the oxygen sensor.
 
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 Originally Posted By: wafrederick1
Do a back pressure test using a back pressure gauge.Most parts stores sell them and you put in place of the oxygen sensor.
Or use a vacuum gauge. Rev engine slowly in neutral. As engine revs the gauge will edge near "0" if there is a clog.
 

another Todd

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Just went for a drive, it does rev higher in gear. Live data showed: Calc load was 41% idling in gear with AC on. About 30% idling in park with AC off. On road from stop...1/4 throttle showed 100%. These sound very high to me. Engine temp indicated lower than the dash guage by about 15 degrees. TPS 17 @ idle. Thanks punisher, I forgot about that test. I will try it.
 
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Remember, the emissions warranty covers a defective cat. Not a cat ruined by a misfiring engine or oil consumption.
 
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 Originally Posted By: MrCritical
Remember, the emissions warranty covers a defective cat. Not a cat ruined by a misfiring engine or oil consumption.
+1 although ive seen people throw temper tantrums and get them covered anyway. the best are when people want us (parts dept) to hand them to the customer over the front counter, or they want the old ones back. they usually get royally upset when we explain to them about warranty coverage and it must be done through service and ford gets the old cats back since they paid for the new ones.
 
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Dirty or blown MAF? Has the throttle body or IACV been cleaned?
 
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I have found on properly running cars the OBDII "load" is fictional, 30% in neutral. I think it's a "bias" used by internal logic. Decel in gear is usually the only way to get near 0% load. The o2 backpressure test is even easier, just pull the sensor and very briefly run it, if it's night and day, there you go.
 
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 Originally Posted By: andyd
How often will a 5yr old cat clog up? Is this a common occurence?
I've got the original cat on an 88 E-150, and a 93 Aerostar with over 173,000 miles. I don't think they clog up that easily unless something is wrong with the engine, like buring a lot of oil, or an overly rich condition, to name a few things.
 

JTK

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Like beanoil says, Trailvoy is a good site for anything GM T360 related. I also owned a 2005 Trailblazer. Plugged cats are somewhat common. The 4.2L I6 has a single cat and it can get overloaded quite easily given the HP rating and low fuel economy of these engines. I've read of other owners, mostly 2003-2004 who've had the same issue. A new converter fixed it. For what ever reason, it plugs or the substrate melts into a block of goo long before you ever get a catalyst inefficiency code. Joel
 
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I have 2 Cat's on my Santa Fe and it has 200K KM (120K Miles) and are original. I checked a few miles back (170K KM) on an exhaust gas analyzer to see something else and it blew almost all 0's! (3/4 original O2 sensors too!) My previous car has it's original cat up until 335K KM (209K Miles) until it needed replacement because it wasn't 100% efficient and would barely fail the emission test by being a tad over on HC's. I think it's how well you look after a vehicles maintenance that determines emission component life.
 
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Engine codes are my first check. Even if there is no light on the dash, you may have codes. Get it checked and it may tell you exactly what is wrong. You can also loosen the exhaust in front of the cat, and see if she runs better [if this is easy for your car]. This could also be a fuel delivery problem, or a faulty MAF.
 
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Or use a laser pointed thermometer gun and point before, at and after the converter and see what the readings are... This will help determine if it's working.
 
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we had a catalytic converter plug . Car became sluggish and stopped running and had to pull to side of road . If I remember right the temperature gage shot up as well .
 
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