kechal

My 2014 981 Boxster S is misfiring on cylinders 1, 2, and 3 (which is causing the PSM and auto stop/start to disengage). I figured it was the common coil failure so I replaced all six coils and plugs and that seemed to solve the issue for about a day and then all the yellow warnings popped up again. Now, I wonder if it is a fuel injector issue but it seems strange three would go bad and all on the same bank. I just got an iCarsoft CR Max and do not have any faults directly pointing to the fuel injectors. Any insights on (1) Could it be the injectors all failing on one bank? (2) Other potential causes of the misfires? (3) How difficult a job is it to DIY the replacement of the injectors? Thanks.

Noah Fect

An entire bank of cylinders? I'd look for what's in common... cam position sensor, maybe? Rodent damage to ECU wiring harness?

chaos2984

see if you can monitor the misfire counted and see if you have 1 cylinder misfiring more that the other. It could propagate over and cause phantom misses on other cylinders. I would look at what your fuel trim is on that bank vs the other that is running fine. That will tell you a lot on what is going on. If your seeing a high + % then its trying to add a ton of fuel and it might be a rich misfire. That means your getting unmetered air into the engine on that side. If your high - % that means your dumping to much fuel trying to compensate for more air in the intake charge than normal. I would look at what the O2 senosrs are doing as well. Compare those items to the bank that is running correctly and see what you got.

kechal

I should have mentioned in my original post; that prior to replacing the coils and plugs, I got error codes for misfires on cyl. 1, 2, and 6 as well as a P2317 (indicating a problem with coil "F", which would be cyl 6).

Jim Cobb

That’s the way it worked on my 981 GT4. Are you sure the codes were reset after the new coils/plugs were installed? I ask only because this happened to me.

Noah Fect

I'm tempted to say "Put me down for $5 on the wiring harness." Hopefully wrong about that, though.

KBell

kechal

Any other problems?
Running fine despite misfire on 1,2,3?
Any weird "electrical gremlins" starting to pop up?

okie981

Crankshaft position sensor is a known weak link on these cars. Can't say it's causing your codes or problems, but one mod that is done to any 981 that is to be used for racing or serious track day work is to put the 991.X GT3 crank position sensor in.

kechal

I am also getting the code for a bad variable valve lift solenoid, which I have just ordered. I suspect replacing this will resolve the issues. Fortunately, it looks like a relatively easy replacement. I will update after the replacement. Thanks to all who have responded!

chaos2984

This can cause misfires as well if that solenoid is sticking and causing valve timing issues when not commanded. Hopefully this will fix it for you.

kechal

Just wanted to close the loop on this. So, after replacing the coils (which I knew at least 1 was bad) and plugs, I was still getting misfire codes. Replacing the valve lifter sensor solves the problem. Car runs great! Maybe my imagination but the car feels quicker (I also cleaned and re oiled my K&M air filters.) thanks all for the comments and suggestions!

john981

I had in my last base 981 the same issue. Hooked up my code reader and bunch of random miss fires. Changed all 6 coils and spark plugs and nothing changed. I had also brand new pair of air filters. At one point I sold the car but it was very annoying to know I have all the miss fires. Can you please do a quick write up how you changed the valve lifter sensor? Even though the engines are not the same but I think the solution could be the same. Thank YOU!