Mechanic says I need a new cat

[zync]

I'm just hitting above 100k and got tuned to stage 1 at about 80k. For some time now, I've been having misfire after misfire and been advised to change ignition coil after ignition coil.

Apparently, the same issue is coming back. Acceleration is sluggish. Boost is low. There's a huge restriction in the lower RPMs. I did have 8 codes showing up but my friend cleared them, so now I'm just waiting for them to come back. I recall them being about 2-3 cylinders misfiring and the boost being low.

Two mechanics noted that the cat is getting built up of carbon and considered that I should get a new one. About $1300.. I do not want to do that.

So my question is, living in California, can I buy a downpipe with an aftermarket cat and be ok? I don't have a check engine light so I'll be ok if I switch to stock if I need to be smogged? Right now all I have exhaust-wise is a cat and a muffler with a DSG transmission. I am not very educated in cars so all the patience and guidance help much.

 

[semperfi]

I'm just hitting above 100k and got tuned to stage 1 at about 80k. For some time now, I've been having misfire after misfire and been advised to change ignition coil after ignition coil.

Apparently, the same issue is coming back. Acceleration is sluggish. Boost is low. There's a huge restriction in the lower RPMs. I did have 8 codes showing up but my friend cleared them, so now I'm just waiting for them to come back. I recall them being about 2-3 cylinders misfiring and the boost being low.

Two mechanics noted that the cat is getting built up of carbon and considered that I should get a new one. About $1300.. I do not want to do that.

So my question is, living in California, can I buy a downpipe with an aftermarket cat and be ok? I don't have a check engine light so I'll be ok if I switch to stock if I need to be smogged? Right now all I have exhaust-wise is a cat and a muffler with a DSG transmission. I am not very educated in cars so all the patience and guidance help much.

Have you checked all vacuum lines? Sounds like that, pcv, intake runners (carbon buildup)????

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[zync]

Have you checked all vacuum lines? Sounds like that, pcv, intake runners (carbon buildup)????

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Hey there thank you for replying and giving your opinion. I am quite car illiterate. How would I do those things? I can of course Google it.. also, I rather not have a mechanic worl on everything on my car - so I wish to educate myself.


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[zync]

Any help is much appreciated. I read for carbon cleaning I can go 65-70mph on 4th gear for 20 minutes to clean. Can anyone confirm this? Really need to educate myself..


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[mto386]

You really needed the codes. If you haven't done a carbon cleaning in 100k, I think it's time. What part of CA?

 

[Speeddemon691]

Tell your Mech your a dog person lol




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[zync]

You really needed the codes. If you haven't done a carbon cleaning in 100k, I think it's time. What part of CA?

I'm really just waiting on them to come up again. Bought myself a scanner just for that. Im in Stockton.


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[zync]

Tell your Mech your a dog person lol




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I'll tell DMV as well when I need to smog!


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[Howcanifixthis?]

That sucks man i feel for you! My cat is bad as well im saving up for a new exhaust system that will eliminate the cat converter (cobb turbo back). Sucks that your in CA i know that state is strict.

 

[zync]

That sucks man i feel for you! My cat is bad as well im saving up for a new exhaust system that will eliminate the cat converter (cobb turbo back). Sucks that your in CA i know that state is strict.

Ah no not another! I was thinking about getting a tbe and simply switching it out with my stock exhaust when I need to smog. I'm assuming that would work? Thing is, tbe can be as much as a new cat!


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[snobrdrdan]

I read for carbon cleaning I can go 65-70mph on 4th gear for 20 minutes to clean. Can anyone confirm this?

100% false

Intake manifold has to come off and you blast or scrub the back of the valves

 

[zync]

100% false



Intake manifold has to come off and you blast or scrub the back of the valves

Thank you! I'm not sure what that even it but I'm sure I can search for that. What would be safe to clean it with? Please excuse my ignorance and thank you again.


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[Laimface]

Thank you! I'm not sure what that even it but I'm sure I can search for that. What would be safe to clean it with? Please excuse my ignorance and thank you again.


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This is a mechanics job really. You've said you're quite car illiterate, so this isn't something you'd want to try yourself until you have more experience. I'd do my own but I'm a lazy bugger, so will get the shop to do it when they fit my new clutch and downpipe.

 

[zync]

This is a mechanics job really. You've said you're quite car illiterate, so this isn't something you'd want to try yourself until you have more experience. I'd do my own but I'm a lazy bugger, so will get the shop to do it when they fit my new clutch and downpipe.

Totally agree with you! However, two mechanics concluded I need a new cat. I'm wondering if that's really the case? Hoping these codes come up again so I can show you guys. Is there anyway I can see codes that have been cleared? I bought a OBD 2 thing that connects via wifi and I have an app for it. I'll have to play around with it more. Thank you for replying and any help will be appreciated.


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[lilonespaz]

Totally agree with you! However, two mechanics concluded I need a new cat. I'm wondering if that's really the case? Hoping these codes come up again so I can show you guys. Is there anyway I can see codes that have been cleared? I bought a OBD 2 thing that connects via wifi and I have an app for it. I'll have to play around with it more. Thank you for replying and any help will be appreciated.


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you can try scanning but if you cleared them you will just need to wait for them to come back.

You said you changed coils...

Did you change spark plugs and coils for all of them? or just one at a time?
I personally would do plugs and coils all together
https://www.urotuning.com/Electrical-Tune-Up-Kit-2-0T-w-Red-R8-Coilpacks-p/20t_tuneup_r8_coils.htm

Carbon cleaning is probably needed as well if you're over 100k and never had it done.. Its expensive some shops charge like $400 but i think the average is closer to $800 but it will clean up the valves and helps most people that have some misfires and bad fuel economy.

If your cat is clogged up and need replacing that could be an issue too.. without the codes we cant really diagnose what could be the issue.

I would do the spark plugs and coils as its like $140 and pretty much anyone can do it with $15 bucks worth of tools from harbor freight and a you-tube video.

Then get the codes and start telling us what they are so we can maybe help further diagnose.

Go to a third shop/mechanic and dont mention anything about the others or what they said and see what he comes up with.. If he comes up with the CAT too without being informed you were already made aware then it most likely is a main culprit... some mechanics will just agree with what the first person says so they dont have to spend a lot of time looking into it. Not all but some do that.