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baker_g

Sudden Misfire Cyl 4,5 & 6

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I was starting to feel really good about having just saved a $400 labor bill by replacing a new coolant reservoir and thermostat myself - only to discover a bad misfire upon restart. Computer codes P0300 (random misfire), P0306, P0304, P0305, P1319, P1313, P1318, and P1314 all misfire codes for cyl 4,5 & 6. The only thing that I can think of was that I had to disconnect the fuel lines to replace the reservoir. Coil wires appear to be intact. Any ideas about what I could have screwed up? I didn't knowingly disconnect anything else but not that familiar yet with the 996 ignition system. Appreciate any leads.

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I do not know what you've loosened to replace the coolant tank, but the codes refer to cylinder. 4-5 en 6 which are on the opposite ( right ) side of the engine. Is it possible that you chose the wrong row of cylinders for inspection?

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I was starting to feel really good about having just saved a $400 labor bill by replacing a new coolant reservoir and thermostat myself - only to discover a bad misfire upon restart. Computer codes P0300 (random misfire), P0306, P0304, P0305, P1319, P1313, P1318, and P1314 all misfire codes for cyl 4,5 & 6. The only thing that I can think of was that I had to disconnect the fuel lines to replace the reservoir. Coil wires appear to be intact. Any ideas about what I could have screwed up? I didn't knowingly disconnect anything else but not that familiar yet with the 996 ignition system. Appreciate any leads.

Your coils are cracked, you spilled some water/coolant over when refilling, and this is probably the case. I replaced all 6 coils and plugs and the codes cleared.

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Did you get the car up to operating temp and did it overheat?

Did you refill the coolant system according to procedure (to ensure no air pockets?)

Perhaps the fuel lines aren't reconnected and there is a leak causing less than required fuel on the 4-6 side (the fuel enters the 1-3 rail side as you know).

You could try swapping coil packs from side to side to see if the misfires follow.

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Thanks everyone for the suggestions. Could the misfire possibly have been related to air in the fuel line after disconnecting them to replace the reservoir. I was pleasently surprised when today the problem "resolved" itself. Wish more problems did this. I reset computer and all codes have resolved. Go figure. The fuel line for the right bank is quite long and perhaps trapped air affected fuel pressure on that bank as the misfires were quite serious. If this was the problem, not sure how the DME would have set all the error codes. Anyway, I'm happy the problem appears to be solved.

This site is great. Thanks to all that contribute to help us newbies get familiar with these wonderful cars.

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