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*HELP* P0300 Multi Misfire

This is a discussion on *HELP* P0300 Multi Misfire within the Firebird / WS6 forums, part of the Vehicle Specific category; I was out today on the freeway at different speeds and I have never missed a gear. then I get ...

  1. #1
    Junior Member shwagg's Avatar
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    2004 Yamaha R1
    Black 2001 WS6

    *HELP* P0300 Multi Misfire

    I was out today on the freeway at different speeds and I have never missed a gear. then I get off and get to a light and the engine is running ruff with a definate miss. I mean the shifter is shaking my hand off at low rpm take off speeds. Then the ses light comes on and flashes. I limp it home and get the predetor on it and it gives me p0300. multi misfire. I do have a sqeeky belt that only starts after its up to temp and its more of a ringing kind of noise. I do not have a K&N, have not washed the engine bay in awhile. I have not had any problems up til now. I do realize the predetor is not the cause but i still went back to factory tune just in case. The car is bone stock except for the SLP Lid and Skip shift eliminator. I have not changed the plugs or wires the car only has 26,600 those wires and plugs should have plenty of life. If it was a crank sensor wouldnt the car be dead in the water? If all else fails I just talked to my neighbor who is the service manager at the local pontiac dealership and he said he could get it in and charge me 35.00 an hour.What could this be at 26,600 miles? Any insite would be great, especially if you have seen this before. Thanks in advance for any help.

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    Junior Member shwagg's Avatar
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    2004 Yamaha R1
    Black 2001 WS6

    The car is a 2001 WS6. I just finished going through the plugs and all have what seems to be spark. I used a spare plug and unplugged one spark plug at a time and all had spark but this is now way to be sure there is enough spark though. I then removed the plug and two of them looked wet but all had a tan color and where the stock Denso. The gap was set to .060 (looks large). What is the the flow rate of the stock injectors. I might have to go with the ford SVO injectors but I am not sure which ones to get without having to change the fuel pressure regulator. It did not give any cylinder number just the P0300.

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    Senior Member Danger731's Avatar
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    On my Silverado, same code 0300 multi miss fires, They thought it was the fuel pump, turned out to be the fuel pressure regulator. 89 bucks, good luck. btw my ses code went on during the smog check. they diagnosed and fixed it there for 89 bucks for the part. seems at higher RPM's it would missfire due to the gas issue. hook a fuel pressure sensor to your fuel line check that , if good pressure then it is your FPR.

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    Junior Member shwagg's Avatar
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    2004 Yamaha R1
    Black 2001 WS6

    Alright, I found the problem to be two bad spark plug wires, #1 cylinder coil pack, and a bad spark plug. Thanks to everyone who helped. Take care and be safe.

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    Member lrader99's Avatar
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    flat black
    sorry..but the LS HAS NO FUEL PRESSURE REGULATOR....it doesnt exist...the pump is pulse width modulated...thats how you get a constant fuel pressure

  6. #6
    Junior Member shwagg's Avatar
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    2004 Yamaha R1
    Black 2001 WS6

    Quote Originally Posted by lrader99 View Post
    sorry..but the LS HAS NO FUEL PRESSURE REGULATOR....it doesnt exist...the pump is pulse width modulated...thats how you get a constant fuel pressure
    Thanks for the info...I guess this goes to show how much I know about the LS engine. To be honest I moved from a L98 to this LS and I was hoping that my knowledge base would be a direct transfer over but how could I expect technology to stand still for 10 years. Thanks for the info

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    Member lrader99's Avatar
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    flat black
    a real easy way to tell....that little thing on the intake manifold that looks like a vacuum diaphragm is actually an acumulator...it stores extra fuel so that when you stomp in her throat it has a lil extra for the pump to play catch up...you can tell its an acumulator by the lack of vacuum line running to it.

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    Senior Member Danger731's Avatar
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    Quote Originally Posted by lrader99 View Post
    a real easy way to tell....that little thing on the intake manifold that looks like a vacuum diaphragm is actually an acumulator...it stores extra fuel so that when you stomp in her throat it has a lil extra for the pump to play catch up...you can tell its an acumulator by the lack of vacuum line running to it.

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