standup triple

I have a 2009 base corvette and the dealership told me that my car is running sluggish because the cats could be getting clogged up and therefore causing it to run this way.? I didnt even take my car in for that , I had a weird noise upon real fast deceleration which they didnt know what it was either. They said it could be my harmonic balancer because it is wobbling. So my question is can I get catalytic converters checked for clogging up and causing the car to run sluggish? I just do not feel like spending all that money on replacing them and finding out that they were not clogged and it is something else that is causing the sluggishness. My check engine light is on and it is throwing a misfire code he said it is a multiple misfire code..? Anyways is there a way to test CATS?

Solaris

After I got a supercharger my cats started to clog up and cause misfires. When I removed them, the honeycombs were broken up on the entry side. You might see the same thing if you removed yours. It's not that hard to take them off to look.

C5 Diag

There are a number of ways to check for a clogged cat but remember a clogged cat is usually the “effect” and not the cause !!…misfires, an O2 sensor that is “stuck” lean causing excess fuel to be burned inside the cat…I had this same condition on my own car a few weeks ago and I was able to quickly diagnose it before my bank 1 cat was damaged…I had misfires on every bank 1 cylinders and the smelly exhaust was my first symptom !!…an old school test with a vacuum gauge can be done, if the cats substrate is damaged and coming apart taking a rubber mallet to it makes a noticeable rattle when struck…a back pressure test with a gauge taken at the upstream O2 sensor can also be done…any competent shop should be able to accomplish these tests…good luck !!

standup triple

Oh yeah ok well thanks for the help, I have had multiple misfires from both banks and not sure what is causing the misfires? You are exactly right about the effect being clogged cats but what is causing the misfires ? Can the clogged cats send a message to the O2 sensors that will throw a check engine? I only have noticed the sluggishness recently and it feels like a weak spark or ignition. Mostly it is at the low end and it feels just sluggish .. Not stumbling but sluggish .. I have also had my traction control and active handling service light come on periodically and it just goes away if I restart the vehicle. I took it in to the dealership because of the active handling and traction control service lights coming on and the dealer told me that they have to be on when I bring it in or they cant figure out what it is .. and wouldn't you know it .. It did not come on that day ... it is again now but my point is I took my car in for one thing and got all this other diagnosis like my clogged cats and my harmonic balancer needs replaced and my radiator carriage is bent up and needs to be replaced ... Then I paid them 157.00 and got my keys and I drove it home with nothing really further along or known to be the culprit at all.. But I paid 157.00 to be able to be told this by the dealer oh and they said there best mechanic was the one looking at it and he is only going to charge me 1 hour of labor for this useless information ... Oh well thank you Chevy dealership I am so happy that I know absolutely nothing more then the day before I took it in to you but I am !57.00 lighter.. Thanks for the donation is what they should have said oh and here are your keys sir.... This is why I do not like dealerships because what really happened ? I did get told that it was going to be 3000 for the balancer and 3000 for the radiator carriage and another 2500 for the cats and do i really want to spend 8500 to have this done and it might not be the reason my car is sluggish or why my check engine light is on, But I will have a new radiator carriage and new cats and a new harmonic balancer .. I think I can do better then 8500 for these repairs right? I mean my car is only worth maybe 20,000 ...? I want to buy a C7 so should I sell this car private to a private party for 20,000 and let them figure it out and how much is a c7 base model right now ? 30,000 ? 35,000?
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C5 Diag

If you are getting random misfires from both banks clogged cats can certainly cause that !!…if the engine can’t “breathe” the engine will be low on power and since those spent exhaust gases can’t be expelled through the exhaust you won’t have a proper mixture of fuel and oxygen to be ignited in the combustion chamber…there is no way for a clogged cat to send any type of a message…that is the engine computers job !!…you will get a P0430 which is a cat efficiency code which is the cats inability to store oxygen but you have a mechanical defect… good 2 part video below.

BadAV

You very likely destroyed the converters by continuing to drive the car with a multiple misfire flashing check engine light. The owner's manual tells you to not drive the car with a flashing SES light for this very reason. Get the cause of the SES light fixed, then go to a good muffler shop and have them install new converters for something like $250 each.

C5 Diag

OP is in California so yes getting an “EPA”certified cat can be had for $250.00 but he will need a CARB certified cat…3 to 4 times more expensive !!

BadAV

ICNLT because of that type of stupidity. Then he should start looking for OEM replacements on the forum or at salvage yards.

C5 Diag

There is a TSB concerning CAT failures for 2016 and prior GM cars...bad engine block ground terminals...pic looks like an ECM block ground.

Matt Zed

I've seen people install a pressure gauge in the secondary o2 sensor or auxillary o2 sensor bung of a header and test for clogged cats. 2 to 3 lbs of pressure was an indicator of a plugged up cat.

standup triple

Okay now we are getting somewhere, thank you Matt Zed I was waiting for a member who understands my issue and can offer good advise to my issue. I like that idea as it does not include getting my cats taken out to see if they are clogged and finding out they are not clogged then what? I just paid a thousand dollars to take my exhaust apart to find out my cats are not clogged but since I have it taken apart i might as well install new cats and expensive here in Ca. not 250 each thats for sure WOW those are 1980 prices here in CA. everything is way more than rest of country ... I would be looking at least 1500 to replace two cats here ...

standup triple

It is against the law here in Ca to put on used cats from a salvage yard.. I will take it to an exhaust shop to see if the cats are indeed clogged ... Thanks

standup triple

Is it also likely that the cats just got clogged over time and they being clogged would throw the check engine light so they are the reason for the check engine light not the coils or plugs or wires or anything else for that matter? I have check engine light on because my cats are clogged ?? right ?

C5 Diag

Using a vacuum gauge is the easiest check...you don't even have to remove an O2 sensor or get under the car...just plug into a vacuum port at the intake manifold !!

BadAV

You said you had a flashing SES light, which is typically multiple misfires. Continuing to drive with a flashing SES light can lead to clogged cats because of unburned fuel being dumped into them, which is why the owner's manual tells you to not continue driving. You need to determine and resolve the real issue before you put new cats on or you will likely end up in the same situation again in short order. Or just ignore good advice and do what you want. You would be well advised to spend a little time to find a good shop that knows what they are doing, that will do a proper diagnosis, and attempt to fix it right the first time.

C6_Racer_X

A pressure gauge in one of the o2 sensor ports is most accurate way to measure.

A much easier diagnostic test is to use a vacuum gauge (or OBD-II app/scan tool monitoring manifold pressure). With engine at operating temperature, turn off all loads (a/c off lights offb, radio off' etc.). Transmission in park or neutral. Operate engine with no loadsat 1000 RPMs and note the vacuum (or pressure) reading. Increase engine speed to 2500 RPMs and check vacuum (pressure) at that engine speed with no load.

Vacuum should be higher (manifold pressure lower) at 2500 RPMs with no load than at 1000 RPMs with no load. If vacuum drops (manifold pressure increases) at 2500 RPMs, the exhaust is restricted.

standup triple

yes I concur, Badav.. I need to find a good shop that is the easiest solution for me since I have a second MAJOR repair that is also due over due I should say , I have the death wobble.

C5 Diag

NO !!…the engine computer does NOT know your cats are clogged…they can’t figure out what the temperature is or pressure either…they rely on voltage signals from different sensors in the car to process information…they are the result of something ELSE that caused them to clog…the cat should last the life of the car…you must have had something going on for a while like misfires, over rich fuel mixture, oil contamination caused by excessive blowby or engine coolant caused by a leaking head gasket that was ignored…if you don’t figure out what caused it new cats will fail again over time !!

standup triple

Well it has got much worse just in a day or two and it is so sluggish and it is barely driving now. I think that is better for finding what is causing all this. Thanks I will go searching on Monday for a shop

449er

Good advice above