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Phantom305
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Apr 25, 2021, 8:05 AM
Post #26 of 34
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Re: Knocking coming from cat
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i took my airbox out and it reeks of gas!! So apparently that means its got a leaky injector, That's simply not true. No connection at all. But a plugged cat could do that.
Yea im gunna take the pre cat o2 sensor out and see if it relieves some pressure
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Phantom305
User
Apr 25, 2021, 8:07 AM
Post #27 of 34
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Re: Knocking coming from cat
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Plugs were replaced last year and i took them out last night they looked ok but definitely running rich, so i think i might have two problems- bad injectors... and a clogged cat
I believe that causes pre combustion which would cause a knock but to my understanding if it was precombustion it would be much louder than what im having
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 25, 2021, 8:12 AM
Post #28 of 34
(1254 views)
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Re: Knocking coming from cat
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I don't know where you are getting these ideas, probably Dr. Google but you are wrong on most of your assumptions.
I have seen nothing in your description that points to an injector problem or even rich mixture. You have a computer to tell you when it sees issues like that.
Same goes for the pre-ignition. Rich mixture doesn't cause that and it doesn't happen at idle.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Apr 25, 2021, 8:13 AM)
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Phantom305
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Apr 25, 2021, 9:00 AM
Post #29 of 34
(1242 views)
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Re: Knocking coming from cat
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Well maybe so but i just took out the o2 right before the cat and it feels like a new truck, so i think there was something broken or clogged in the cat causing whatever noise i was hearing, im gunna pull the cat and see what i can see
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Phantom305
User
Apr 25, 2021, 9:04 AM
Post #30 of 34
(1237 views)
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Re: Knocking coming from cat
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Thanks for being blunt with me ive only been working on cars for a few years so I definitely have a lot to learn... this is one of the chevys with the spider injectors(csfi) do you think it would be worth replacing anyway? The truck has 200k runs good but the replacement is mpfi which everyone keeps telling me is much better
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 25, 2021, 9:05 AM
Post #31 of 34
(1235 views)
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Re: Knocking coming from cat
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Precisely what I told you on the first reply.
The noise and the clogging don't necessarily go together. You can have one without the other.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Phantom305
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Apr 25, 2021, 9:18 AM
Post #33 of 34
(1225 views)
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Re: Knocking coming from cat
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Yea i gotcha, but seeing as the noise is only in the cat i would say it’s probably a safe bet that its the cat? I mean it sounds like a metallicy knock to me but im also not a pro technician
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Phantom305
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Apr 25, 2021, 9:18 AM
Post #34 of 34
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Re: Knocking coming from cat
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Ok yea thanks!
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1989 toyota pickup 3.0 crank no start
Please Help - Knock sound & engine fail
