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I have a 2000 chevy impala with 190,000 miles on it that I just put another engine in. my question is, it runs rough and is not drivable because of poor engine performance in that it has no power and smells of gas but no gas leaks. I found an exhaust leak were the headers attach to the exhaust pipe before the cat. it is my understanding that the cat is telling the computer its not reading enough fuel in the exhaust and is adjusting the air fuel mixture. the check engine light is on when the car starts but starts blinking after 10-20 seconds of idling. I don’t know if that is from the same problem or not. let me know what you think.
note: the new engine had 70,000 miles on it when I took it out of the other car.
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[quote=”joeswayornoway” post=82607]I have a 2000 chevy impala with 190,000 miles on it that I just put another engine in. my question is, it runs rough and is not drivable because of poor engine performance in that it has no power and smells of gas but no gas leaks. I found an exhaust leak were the headers attach to the exhaust pipe before the cat. it is my understanding that the cat is telling the computer its not reading enough fuel in the exhaust and is adjusting the air fuel mixture. the check engine light is on when the car starts but starts blinking after 10-20 seconds of idling. I don’t know if that is from the same problem or not. let me know what you think.
note: the new engine had 70,000 miles on it when I took it out of the other car.[/quote]
Watch this video
I have a feeling you might have a plugged exhaust.
do you think that had something to do with the new engine being put in it? I didn’t have this problem with the old engine. the flashing check engine light never came on nor did the exhaust leak or the smell of gas.
[quote=”joeswayornoway” post=82610]do you think that had something to do with the new engine being put in it? I didn’t have this problem with the old engine. the flashing check engine light never came on nor did the exhaust leak or the smell of gas.[/quote]
No, if it did not start til the new motor was installed it is more likely something is wrong with the new motor.
Oh if you have an injector leaking (or a dead ignition miss) raw fuel is dumped into the exhaust, the O2 Sensor will signal a lean condition making the PCM add more fuel making your situation worse. The reason why is the sensor can not detect raw fuel, all it sees is the O2 that the bad cylinder pumped through without burning. Combustion reduces the O2 by combining it with the gasoline and trace elements to form CO CO2 H2O and NOx (plus the trace elements) (your converter is designed to reduce those to H2O and CO2) If that cylinder does not combust there is more free O2 left over than there would be if the cylinder fired.
If you notice when I short out the plug wire the O2 sensor shows a low voltage (lean) (even though the injector is still firing and spraying fuel into the cylinder) and the trims go positive as the computer adds fuel to compensate for the incorrectly perceived lean condition.
The blinking is your PCM trying to tell you that you have a Type A misfire, which is a misfire that could be spraying raw fuel into the cylinder and doing severe damage to the converter and the engine. Often on newer cars the ECM will actually shut off the injector to reduce the damage to the converter.
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