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Discussion Starter · #1 ·
so hello my name its Bryan and I own a 2003 350z, last year I had an issue that when the car was in idle, the car would start making a nocking and popping sound and the oil pressure would go all the way to the top. so I took it to the mechanic and he end up telling me that It was the oil pump and the timing chain needed to be replace. so I end up taking it to him this year and he end up changing the oil pump and the timing and after all. the car kept making the same nocking and popping sound. so he told me that it was better to change the engine, so I agree to change it , he end up putting an engine with 77k and after he replace it the car came with the situation of doing the same problems it was doing with the old engine.. has anyone had the same issue or solution to this situation?
 

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How many miles are on this Z? It's unlikely anybody has had the exact same problem, but can you describe the "rocking and popping" sound further? Is it coming from the exhaust? Did you pull any codes before you pulled the motor?
 

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Discussion Starter · #3 ·
So my z original had 99k miles .. but then the nocking and popping sound start sounding .. the noises comes from the engine but u can hear it coming out of the exhaust .. and as of right now after they change the engine it started giving this codes-p0550 p0031 p0051 and p0300 and the popping and knocking sound doesn’t go away even if I clear the codes. What also doesn’t make sense it’s the original engine was doing the same scenario of the knocking and popping sound and what doesn’t make sense why the new engine which only has 77k miles it’s making the same problems .
 

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P0300 indicates multiple cylinder misfires and this is usually not an engine failure. The fact that you still have the same symptoms seems to indicate you STILL have the same electronic issues. Did you check the 02 sensors and harness wiring before replacing the engine?
 

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Discussion Starter · #7 ·
P0300 indicates multiple cylinder misfires and this is usually not an engine failure. The fact that you still have the same symptoms seems to indicate you STILL have the same electronic issues. Did you check the 02 sensors and harness wiring before replacing the engine?
Yes the harness and the 02 sensors were good .. like that’s what I don’t understand what’s causing this issue .. cause to have the same symptoms of the old engine the means that the old engine was good and was not the issue of the timming been off .. cause on the new one nothing was touch besides installing it.
 

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Discussion Starter · #8 ·
Yes the harness and the 02 sensors were good .. like that’s what I don’t understand what’s causing this issue .. cause to have the same symptoms of the old engine the means that the old engine was good and was not the issue of the timming been off .. cause on the new one nothing was touch besides installing it.
Could it be the ECU that is mess up? Cause other than that I really can’t think of anything else . Cause my computer doesn’t give no other codes besides the one I described.?
 

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Did you use the same harness and ECM from the old engine when you swapped over to the used one?
 

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Since your symptoms remained the same, it seems likely that the parts you didn't change are responsible. Which ones are impossible to determine from behind a keyboard.
 

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Discussion Starter · #12 ·
But you don’t think it could be the ECU that is making this issue cause what else can be causing this issue
 

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Certainly, it could be the ECM, but it seems that you had many more codes show up after swapping motors. Is this due to a mismatched engine, harness or ECM? I sure don't have those answers.
 

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Discussion Starter · #14 ·
So today I empty out the gas and put fresh gas and the popping and knocking sound wasn’t loud it was more less and not loud but I noticed that it was only making the popping sounds from the left exhaust. Cause when you touch the right exhaust the air was coming normal but on the left side it was coming out with pressure. And it keeps only getting the code p0300 for multiple misfires
 

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Not sure I understand. Did the other codes you listed in post #1 go away? Is P0300 the only one left? What kind of exhaust is on this Z?
 

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So I had the P0300 and my engine was running badly and it turned out to be a bad O2 sensor even though it didn't throw a code specifically for that. I have a 2004.5 which has wideband upstream O2 sensors. I believe the 2003 has narrow band but I'm not sure if thats relevant. About the high oil pressure reading, when those sensors go bad they read full high on the gauge.

Since the symptoms only seem to occur in one bank my money is on a bad O2 sensor. You could switch the sensors and see if the problem follows it, just replace it, or read the live data with a scan tool and look at the O2 sensor voltages. Should be about the same voltage unless you have my year in which case the voltage of one is supposed to be half of the other. I don't know why they did that.
 
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