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P0351, p0300, rattling noise (ping?), and engine occasionally “skipping”
Okay so I have thrown countless parts and man hours at my 2003 blazer. It runs well on the highway, but under acceleration, it rattles (I believe pinging) and it has 2 codes, p0351 that popped up after i replaced the distributor, and p0300 that i have thrown countless new parts at but it still remains. I just replaced the ignition coil and ignition control module and it still has the p0351, so Im at a loss. I believe it is running lean since the exhaust is quite hot and smells hot and dry and the plugs seem to say it runs lean as well. I will try replacing the fuel injector spider since I may have broken it when i replaced the lower intake gaskets.
but what troubles me now is why on earth this p0351 wont go away. Everyone says it is ICM or coil, but Ive replaced those. Could it be the ecm or wiring? If so, how would the wiring even get damaged? How do i test the ECM and where is it located? Thank you in advance for any help, I am getting very frustrated with this machine. I treat her like a damn princess and shes still got attitude!
Whenever you get a code like P0351 it means the system (ignition in this case) has a problem and the system components are just one possibility. In older vehicles especially, there can also be power, ground, or signal wiring problems. The ECM is a possibility but everything else should be ruled out first. P0300 has many possible causes and it can take a while to get to the bottom of that code. Lets start with P0351. One thing you can check are cylinder misfires to see if its really random and how extreme.
Why did you replace the distributor? Did you ever have the P0351 code before the replacement? Is there any carbon arching under the distr cap? What about plugs and wires, were they replaced as well? What brands were used? It is possible for a P0135 code to get set when there is a secondary voltage problem so the distr, wires and plugs need to be in good shape with no timing problems.. Do you have scanning capability that can read CMP retard so we can check your distr registration? Mist the ignition system under the hood in the dark with water to see if you have any arching.
If the secondary side pans out then on to the low voltage ignition system. Here is the factory diagnostic flow, I will be happy to help you with this. The first and easiest thing to check is the quality of the 12v feeds on the pink wires to the coil and ICM and the quality of the ground to the ICM. Inspect all wires and connectors for breaks, shorts, corrosion, bent pins, etc.:
As far as running lean, what do your fuel trims and O2 sensor graphs look like
Whenever you get a code like P0351 it means the system (ignition in this case) has a problem and the system components are just one possibility. In older vehicles especially, there can also be power, ground, or signal wiring problems. The ECM is a possibility but everything else should be ruled out first. P0300 has many possible causes and it can take a while to get to the bottom of that code. Lets start with P0351. One thing you can check are cylinder misfires to see if its really random and how extreme.
Why did you replace the distributor? Did you ever have the P0351 code before the replacement? Is there any carbon arching under the distr cap? What about plugs and wires, were they replaced as well? What brands were used? It is possible for a P0135 code to get set when there is a secondary voltage problem so the distr, wires and plugs need to be in good shape with no timing problems.. Do you have scanning capability that can read CMP retard so we can check your distr registration? Mist the ignition system under the hood in the dark with water to see if you have any arching.
If the secondary side pans out then on to the low voltage ignition system. Here is the factory diagnostic flow, I will be happy to help you with this. The first and easiest thing to check is the quality of the 12v feeds on the pink wires to the coil and ICM and the quality of the ground to the ICM. Inspect all wires and connectors for breaks, shorts, corrosion, bent pins, etc.:
As far as running lean, what do your fuel trims and O2 sensor graphs look like
George
wow thank you for your very thorough response. I ended up replacing the ignition control module and coil pack and reset the CEL, but the P0300 still remains. I believe it is fuel injectors because the oil smells like gas and doesn’t feel very slippery so I am going to replace the whole spider asap, I hope that will fix it. Im tired of chasing problems and pouring money on new parts.
P0351, p0300, rattling noise (ping?), and engine occasionally “skipping”
