Persistent P0301 - flashing MIL - 2002 Civic EX

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Jan 17, 2020

gburch

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Persistent P0301 - flashing MIL - 2002 Civic EX

I have a 2002 Civic EX (D17A2) with 401K miles. I was shocked when the MIL started flashing intermittently on 12-29-2019 (1st time ever, although I have had intermittent misfires before). It got worse the next day (I counted one sequence up to 71 flashes). I also found Code P0301 with my OBD-II reader. Replaced plugs, swapped coil packs (every permutation), sprayed "J" connectors atop valve cover with Liquid Wrench. Sometimes got a DTC code mix, adding P0302 or P0303, but mostly just a single P0301. Also tried a can of BG44K in fuel tank, which I use at least once a year anyway. Then replaced fuel injector #1 (all injectors were clean as a whistle), and replaced fuel tank assembly (couldn't wait for a simple fuel filter to be delivered from Internet source).Cleaned EGR valve, tested its operation & ohmed terminals 1-2-3, and dropped a dose of Seafoam in both EGR ports. Finally, before a long trip I tried simply disconnecting the EGR, and the P0301 went away - of course P1491 appeared, but the misfire problem was solved (sort of). After the trip I replaced the EGR valve, and the PCV vacuum hose (old one was original, although I had changed the PCV valve a few years back). Then tried a massive dose of Seafoam in the EGR ports under the valve. The Seafoam created a smoke cloud for ¾ mi. on my next drive, but none of the above actions has cleared the flashing MIL and P0301, when EGR valve is properly connected. The flashing MIL seems a little less active after the Seafoam in the EGR ports. My questions are these: 1) will the engine suffer damage with EGR valve disconnected - because it was designed to use one? And 2) is there any efficacy in continuing to put Seafoam or other solvents in the EGR ports, and perhaps also down the throttle body? Am I just wasting my time with this? I have seen some pictures and descriptions for DIY removal of the intake manifold to clean EGR channels - enough to make me prefer to mess with a hornets’ nest instead. I have some talent for repair, but also for breaking things (broke every connector latch, while removing wire harness from injectors) and dropping things (nuts and bolts down into the hidden recesses atop the engine). Fortunately I have a magnet probe, which works providing I can see where the nut dropped. Any thoughts would be greatly appreciated. I’m hoping to find someone who has had success clearing a misfire through chemical de-carbonization. My thought is that some EGR channels are blocked, resulting in EGR channel #1 overcompensating with too much exhaust gas in cylinder #1, causing the misfire. OR, carbonization in the manifold itself, causing turbulence and inefficient flame front in cylinder #1, but only when fed exhaust gas through its EGR channel. Any ideas out there? I’m hoping to find a school-trained technician who knows engine theory of operations. -- Regards, Glen

Jan 17, 2020

Colin42

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Re: Persistent P0301 - flashing MIL - 2002 Civic EX

Either take the intake off and clean the passages Or live with the EGR disconnected. If you don't have emissions testing in your area it won't be a problem, fuel mileage many go down a bit