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    Thread: P0300 random misfire.

    1. #1
      Do I turbo it? Jaded_Crown's Avatar
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      P0300 random misfire.

      I've recently had my car serviced and it now comes up with a P0300, the service included both a timing belt and heated O2 sensor, I checked the spark plugs and they are fine. I would appreciate some help identifying the cause, thanks.



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      2004 1.6 Auto Rust Free
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      Could be the plug wires, the coil, or oil in the spark plug tubes depending on the year.

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      Do I turbo it? Jaded_Crown's Avatar
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      it's a 2006 I checked plugs and tubes, haven't tested the coil yet. I had an aftermarket pod filter on the car, which I reverted to standard. idles better with original airbox, but issue still persists.

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      1. My Aveo's 2007 1.2 (petrol + LPG) engine started being not so calm and car was a bit more lazy, same day engine light went on and I had the same P0300 random misfire problem showing on my OBD reader. I did some research myself and tried to replace some parts new and some used... I got new ignition module, cables and spark plugs all for 50 €, also checked injectors at the local car electrician who said they are working good. Nothing helped. Finally my mechanic was available. I told him everything I tried (some sensors replaced, which I had sitting, used). Mechanic figured one cylinder doesn't work and he checked cables going to injectors. Cable of the suspicious cylinder didn't have power. I am not sure where is power for the LPG injectors coming but mechanic opened the big power connector where power for all for injector cables comes from and one had a bad contact. He pushed it a bit and all works now. Seriously? That is it?! No engine light, problem fixed. Engine purrs.
      2. My car gives one all blinker flash when I unlock it with remote, but when I lock it, it doesn't. Also lock/unlock with a key, no flash. I am pretty sure it used to give flash when unlock with a remote. Any ideas?

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      Do I turbo it? Jaded_Crown's Avatar
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      1. I don't think it's one cylinder. I had checked how many missfires I was getting with a diagnostic tool, and it was saying that all the cylinders were missing at various times. Which makes it seem more likely to be an ignition coil issue or maybe a crankshaft or camshaft sensor issue.
      2. Could be something simple, like a battery or debris inside the key fob, probably worth checking those and seeing what happens.

    6. #6
      What's wrong with my car?
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      Are you sure that a diagnostic tool tells you which cylinder exactly, cause mine didn't? I think it just said multiple misfire. Mechanic diagnosed it by pulling out the spark plug cable and returning it one by one while the engine was working. Three times engine started working badly and with one plug nothing happened. That showed that that cylinder was already not working at all.

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      What's wrong with my car?
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      It seems that this forum is dead. We are not getting any answers.

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      What's wrong with my car?
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      Check all your connections first that s what I did to mine

    9. #9
      2004 1.6 Auto Rust Free
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      Quote Originally Posted by Jaded_Crown View Post
      1. I don't think it's one cylinder. I had checked how many missfires I was getting with a diagnostic tool, and it was saying that all the cylinders were missing at various times.
      This statement along with your earlier statement of a new timing belt is making me wonder if the belt was installed incorrectly causing all the misfires.

    10. #10
      Do I turbo it? Jaded_Crown's Avatar
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      I wondered that, I did a bit of research, and it sounds like I should have a noticable amount less power, which I don't. The only thing different is the idle. I wonder if while it was apart if something may have ended up stuck in the intake manifold, potentilly affecting airflow.





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