p0300 and p0412
01-21-2010, 09:00 PM
#1
Staging Lane
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p0300 and p0412 well after an engine swap, i finally turned on my car and it idled ok until it warmed up and then it shut off. I tried turning it on again and it didnt turn on unless i gave it gas. I let it cool down and once it did i turned it on and it idled fine. I took it to autozone and got p0300 (multiple misfires) and p0412 (secondary air injection system fault). After doing research, I came to the conclusion that the p0300 code is caused by the p0412 code. there are no vacuum leaks, no kinked nor broken lines and all the electrical connections seem to be good. Spark plug wires are good, spark plugs are good and so are the coils. also, fuel pressure is 60 and oxygen sensors are new.....So im guessing that to fix my problem i would have to change out the air pump right??? what do you suggest. Thanks for your help
01-22-2010, 10:33 AM
#4
well after an engine swap, i finally turned on my car and it idled ok until it warmed up and then it shut off. I tried turning it on again and it didnt turn on unless i gave it gas. I let it cool down and once it did i turned it on and it idled fine. I took it to autozone and got p0300 (multiple misfires) and p0412 (secondary air injection system fault). After doing research, I came to the conclusion that the p0300 code is caused by the p0412 code. there are no vacuum leaks, no kinked nor broken lines and all the electrical connections seem to be good. Spark plug wires are good, spark plugs are good and so are the coils. also, fuel pressure is 60 and oxygen sensors are new.....So im guessing that to fix my problem i would have to change out the air pump right??? what do you suggest. Thanks for your help
I believe you are having two separate issues here. P0412 with the AIR system, and the P0300 being a random misfire.
In doing an engine swap there are several grounds. Are you sure that you reconnected each one? Especially the grounds that go on the back of the cylinder heads, those are muy importante...also there are a couple ground straps that go from the block to the body. I'd check all of those first since it's easy.
Secondly I would hook up a scan tool and see what the O2's are reading. Just because they are new doesn't mean there still can't be a problem.
The fact that the car runs fine cold but not when its warm might tell us that it has a problem when the car starts taking feedback from the sensors (closed loop).
01-22-2010, 02:18 PM
#7
Staging Lane
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negative I just finished the 30 minute break in. I dont know if this has anything to do with these codes but as for right now im running open headers. Im planning to put the exhaust on as soon as I can fix them codes so I can drive it down to the exhaust shop
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01-22-2010, 09:18 PM
#9
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I had a code p0300 on my 1997 z28 and found out the header had burned the wire harness coming from the pcm going to the 02 sensor. Check your wiring going to to 02.
