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*HELP* P0300 Multi Misfire

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Old 07-31-2006, 09:16 PM
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Default *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.
Old 07-31-2006, 09:36 PM
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Start w/ the basics- spark, fuel, compression.
Old 07-31-2006, 09:46 PM
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Did it say which cylinder (i.e. P0301 for cylinder 1)? If not, you can pull the plugs to make sure they aren't fouled, and check the fuel filter and fuel injectors while you're around. O2 sensors can do the same thing (and those little bastards can go sour anytime, especially if your predator tune was rich).
Old 07-31-2006, 09:50 PM
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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.

Last edited by shwagg; 08-01-2006 at 01:44 AM.
Old 07-31-2006, 10:00 PM
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The fuel injectors are large enough for your car and mods. Check the O2s.
Old 07-31-2006, 11:08 PM
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Originally Posted by JakeFusion™
The fuel injectors are large enough for your car and mods. Check the O2s.
Right, I was refering to the stock injectors on it now incase they are bad and I need new ones.
Old 08-01-2006, 01:10 AM
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What year is your car? 00+ has 28.8 fuel injectors, 98-99 have something like 26 I believe.




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