Are all of these problems related?
05-23-2013, 04:14 PM
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Are all of these problems related? I have '97 Firebird 3.8L. Over the past 6 months or so, there's been a very occasional knock coming from the exhaust. Up until last month, I'd hear it maybe once per 45 min drive. Last month I started having a misfire and the knock became 20x worse.
Fixed the misfire, brought it to an exhaust shop finally. Now to me, the front exhaust hangar looks bad, because there's a good inch of play of in the exhaust up and down and the bolt that holds the cat looks like it's hitting the undercarriage. Can't tell 100 per cent, though, just what it looks like.
They try and tell me the knock is coming from inside the cat, because the honeycombs are broke and those are apparently knocking around. Has anyone ever heard of this? Then they tried to tell me that I had another misfire code appear while it was with them. Along with an o2 sensor code. Along with a "catalyst efficiency low bank" code. All while they had the car for a hour.
Are all of these related? I was think the cat is causing a misfire, or vice versa, the long standing misfire from before ruined the cat. Would the o2 go bad from the cat being clogged? Its sensor 3, so I was thinking there just isn't enough flow through the exhaust and the sensor is reading that, would that trip it? Or does it actually have to be a faulty sensor to trip it?
Codes are P0417, P0300, P0420.
Fixed the misfire, brought it to an exhaust shop finally. Now to me, the front exhaust hangar looks bad, because there's a good inch of play of in the exhaust up and down and the bolt that holds the cat looks like it's hitting the undercarriage. Can't tell 100 per cent, though, just what it looks like.
They try and tell me the knock is coming from inside the cat, because the honeycombs are broke and those are apparently knocking around. Has anyone ever heard of this? Then they tried to tell me that I had another misfire code appear while it was with them. Along with an o2 sensor code. Along with a "catalyst efficiency low bank" code. All while they had the car for a hour.
Are all of these related? I was think the cat is causing a misfire, or vice versa, the long standing misfire from before ruined the cat. Would the o2 go bad from the cat being clogged? Its sensor 3, so I was thinking there just isn't enough flow through the exhaust and the sensor is reading that, would that trip it? Or does it actually have to be a faulty sensor to trip it?
Codes are P0417, P0300, P0420.
Last edited by blittle; 05-23-2013 at 04:28 PM.
05-28-2013, 03:46 PM
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Alright, just an update, so maybe some one can help me. Cat was replaced about an hour ago. Cleared the cat/ o2 sensor code.
Still have a random misfire (P0300) and EVAP emission control system incorrect purge flow (P1441). Replaced 2 vacuum lines for the 1441 code leading off purge solenoid/ egr that were cracked. Couldn't find an exact fit for the egr hose, so it's a little bit smaller, not sure if that would keep the light on? Put a new purge solenoid on, nada.
Misfire is only occurring at high RPM (5,500 was the first time I felt it) and a good idle. The last time I had a random misfire code and thought I cleared it, it was a terrible idle, but it smoothed out after spark plug change/ wires and I didn't think to have the code scanned again, because it felt perfect... Didn't even realize I had another one until it was scanned the other day.
I was recommended to test the fuel pressure, but I'm not 100% sure how. I think it's a good idea, though, because it could possibly cause both codes, couldn't it?
Still have a random misfire (P0300) and EVAP emission control system incorrect purge flow (P1441). Replaced 2 vacuum lines for the 1441 code leading off purge solenoid/ egr that were cracked. Couldn't find an exact fit for the egr hose, so it's a little bit smaller, not sure if that would keep the light on? Put a new purge solenoid on, nada.
Misfire is only occurring at high RPM (5,500 was the first time I felt it) and a good idle. The last time I had a random misfire code and thought I cleared it, it was a terrible idle, but it smoothed out after spark plug change/ wires and I didn't think to have the code scanned again, because it felt perfect... Didn't even realize I had another one until it was scanned the other day.
I was recommended to test the fuel pressure, but I'm not 100% sure how. I think it's a good idea, though, because it could possibly cause both codes, couldn't it?
