Looking for a little advice on CELs for a 97 Z28
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Joined: May 2003
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From: Knoxville, TN
Looking for a little advice on CELs for a 97 Z28
I'm hoping that the experts here can help me. I'm a B-body guy that checks in here from time to time for LT1 info. But I am not at all familiar with common f-body problems. Most of you folks seem to know your stuff with LT1s. My son has a 97 Z28 T-56 car that is bone stock except for a Flowmaster muffler. He's a poor college student living 200 miles away in Atlanta. He has a check engine light and had a friend scan the codes. The codes are 1416 (catalyst efficiency bank 1) and 0420 (air injection system bank 2).
He says that he knows that he has an exhaust leak somewhere up front - he can hear it, but has not crawled under the car to find it yet. About a year ago when he first bought the car, there was a leak in the rubber portion of the AIR pump crossover tube that he had repaired. The car runs just fine.
It has been this way for months, but he is quite the procrastinator. His tags expire this week but he can't get new tags with a CEL because of the emissions down there. I was hoping that you could maybe give us some advice on where to look. With those engine codes, what would you look for? Could it be as simple as finding and fixing the leak to make the CEL go away?
He is a broke college student and is trying to fix this on the cheap. Any tips that you can provide will be greatly appreciated.
He says that he knows that he has an exhaust leak somewhere up front - he can hear it, but has not crawled under the car to find it yet. About a year ago when he first bought the car, there was a leak in the rubber portion of the AIR pump crossover tube that he had repaired. The car runs just fine.
It has been this way for months, but he is quite the procrastinator. His tags expire this week but he can't get new tags with a CEL because of the emissions down there. I was hoping that you could maybe give us some advice on where to look. With those engine codes, what would you look for? Could it be as simple as finding and fixing the leak to make the CEL go away?
He is a broke college student and is trying to fix this on the cheap. Any tips that you can provide will be greatly appreciated.
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Joined: Nov 1998
Posts: 71,122
From: Hell was full so they sent me to NJ
No big deal, but you've got your codes backwards...
P0420 = Three Way Catalytic Converter (TWC) system low efficiency Bank 1
This indicates the after-cat O2 sensor is very close in its readings to the pre-cat sensor. That means the cat isn't storing O2 as required to eliminate emissions. He could try swapping the left and right bank after-cat O2 sensors, to see if the problem stays on Bank 1 (confirms cat failure) of follows the sensor to Bank 2 (O2 sensor problem).
Substituting an "O2 sim" for the problem sensor would eliminate the code.
P1416 = Secondary Air Injection (AIR) system Bank 2
The PCM cycles the AIR pump in closed loop, and looks for an increase in O2 content at the pre-cat O2 sensor. If it doesn't see the O2, it indicates that the air is not making it from the pump to the Bank 2 exhaust manifold. Could be another leaking hose or a stuck check valve.
P0420 = Three Way Catalytic Converter (TWC) system low efficiency Bank 1
This indicates the after-cat O2 sensor is very close in its readings to the pre-cat sensor. That means the cat isn't storing O2 as required to eliminate emissions. He could try swapping the left and right bank after-cat O2 sensors, to see if the problem stays on Bank 1 (confirms cat failure) of follows the sensor to Bank 2 (O2 sensor problem).
Substituting an "O2 sim" for the problem sensor would eliminate the code.
P1416 = Secondary Air Injection (AIR) system Bank 2
The PCM cycles the AIR pump in closed loop, and looks for an increase in O2 content at the pre-cat O2 sensor. If it doesn't see the O2, it indicates that the air is not making it from the pump to the Bank 2 exhaust manifold. Could be another leaking hose or a stuck check valve.
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