phillbert Posted February 23, 2021 Share Posted February 23, 2021 Hi Everyone, new user here but longtime Subaru owner. Was wondering if anybody has dealt with this issue. -Car idles fine and drives fine otherwise normally. There is an unrelated issue with the car when it sits for a period (overnight) and when you first start, it takes about 8-10 seconds to start. After that, it starts fine. My main issue is that when I am on boost (i.e. over 4.5k rpm), the car will pretty much violently cut out and give me a bunch of error lights (check engine, traction control, brake error light, cruise control). It doesn't matter what gear I am in. As soon as I hit that range, it cuts out and codes come on. Running a scanner gives me the error code p0303. I've checked the intercooler hoses and they seem tight. My best guess is the coil pack and/or spark plug and possibly injector. Are these a known common failure on our vehicles? Any help is appreciated. Link to comment Share on other sites More sharing options...
creep_nu Posted February 23, 2021 Share Posted February 23, 2021 (edited) p0303 is a misfire code, so the most likely source is going to be a coil or plug, but like you said an injector or leak may also be at fault. if it's me i'd start with swapping #3 coil to another cylinder and see if the misfire follows/presents a new code for the new cylinder that coil is on. if so, then you've got a bad coil--either replace it or replace all. if the coil is at fault, while replacing them i'd go ahead and replace all of the spark plugs as well if they haven't been done recently since they're cheap and easy maintenance/wear items. if the misfire doesn't follow, i'd inspect the spark plug on cylinder 3 first, and if it all looks good(good gap, electrode is still in place) then you get to start leakdown and/or compression tests. if all of that checks, then you're moving on up to more intensive diagnostics. Edited February 23, 2021 by creep_nu Link to comment Share on other sites More sharing options...
phillbert Posted February 24, 2021 Author Share Posted February 24, 2021 (edited) Thanks. Mechanic swapped coil packs from cylinder 1 with cylinder 3 and went for a test drive. Sure enough, the same thing happened (check engine and the whole she bang). Ran a diagnostic scan and saw misfire cylinder 1 now. Hopefully this will fix my problem.. Edited February 24, 2021 by phillbert Link to comment Share on other sites More sharing options...
creep_nu Posted February 24, 2021 Share Posted February 24, 2021 good stuff! simple is always better... might be worthwhile to switch out all of the coil packs while you're in there, spark plugs too if they haven't been done in a while, if you can afford all of it, but sounds like you should be back on the road soon Link to comment Share on other sites More sharing options...
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