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Misfiring after 100mph!



I used to have this problem, ive got an 05 comp g. the first time this was happening was a bad spark plug, the tards at the shop didn't bother to pull em out and check em. I replaced the plugs and wires, coils and battery. Lately its been rough at WOT between 5-6000 rpm and slightly odd idling, I got some CRC MAF cleaner and its been better. haven't seen any p0300s yet. still chasing that p0171 dragon though...

good luck man
 
I keep getting the po300 code. But yesterday i did a pull and started misfiring at wot on the highway. Im going to replace that pcv vacumn line and spark plugs to see if itll help it only happends around 90 mph. Its rare and depending how u hit the accelerator. So 1 wot pull it misfired and the second one was fine its totally random


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91 i don't think its a fuel system issue because it only happend near 90mph! When i pull 1mph to around 70 80 everything is fine until your at 90 and it starts struggling and misfiring


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My car was doing that. Fine up to 90 ish, sometimes fine up to 101mph and then missfires. And usually at that point one spark plug would be destroyed. I bought this car with an unknown chipped piston. By the time I found out the piston was screwed up, piston 3 and its rings were destroyed. My car is a 99

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Dang hopefully mine are still good. Im going to change the spark plugs and see what happens. Im just hoping its not a big issue because it drives perfect until top end speed.


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I hope so too. You could buy an endoscope and put it in your cylinders and check the pistons that way. Thats what I ended up doing

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Just make sure the camera is like 10mm or smaller. I believe our spark plug holes are 14mm? I bought a 10mm camera and it fits fine

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So my pcv is on the way! When i went to oreilly i got a print out of most common causes and one of the issues indicated checking for leaks or damaged pcv. That hose is not even a factory hose its something else that shouldnt belong there! I think maybe that can cause the misfire or the plugs then from there if not i have to do compression test and see if any internal damage is done but i don't think so


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Nice. PCV is really easy to change. And cheap too. I think I bought one for like $4

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