Danny Buonsanto

Today I got these codes when scanning the check engine warning. Does anyone has had this happen like this and what you think it could be. Obviosly the chances of all 6 cylinders misfiring at once is pretty slim to none. Perhaps its bad coils and plugs that is throwing the ignition sequence off? Any thoughts or insights?

My car is a 1999 Boxster base manual transmission 2.5L Thanks!


P1313 Misfire, Cylinder 1, Emission Relevant

P1314 Misfire, Cylinder 2, Emission Relevant

P1315 Misfire, Cylinder 3, Emission Relevant

P1316 Misfire, Cylinder 4, Emission Relevant

P1318 Misfire, Cylinder 6, Emission Relevant

P1319 Misfire, Emission Relevant

Byprodriver

I would start by removing the spark plugs one at a time to inspect for any clues there. Should be obvious which are working well & which are not. As you remove the plug wire watch for any bad connections between coil pack & plug it's hard to attach properly.

Anker

If its happening on all cylinders its more likely to be a fuel supply problem. Any lean/rich codes?

Macster

Agree it is slim it is plugs/coils. Generally one or two -- mostly just 1 -- plug causes a misfire and that's that. 'course, after one replaces that bad plug/coil the next worst one gets prompted to the worst one and the process begins all over again. You can check the plugs and coils wiring to ensure they all look ok. I'm thinking rodents...

How's the battery? Is the alternator putting out plenty of juice?

A marginal crankshaft position sensor... marginal sensor or a loose sensor, can result in misfires.

Or something amiss (no pun...) with the VarioCam system can cause misfires as the engine controller adjusts fueling to try to get the #2 O2 sensor readings it expects from a healthy engine. I've seen with my 2002 Boxster how the short fuel trim for the bank with what proved to be a bad VarioCam solenoid/actuator was ranging up and down as the engine controller was trying to the right amount of fuel. Tech told me that the engine controller can go so far afield the engine can misfire.

You can try unplugging the MAF from the wiring harness, clearing the codes, and then starting the engine and seeing if the codes come back. I have encountered at least one case where I bad MAF was the cause of misfires.

Any chance the gas is bad/stale?

Byprodriver

"reading" a spark plug is the easiest & most "surefire" way to see what is going on in that cylinder. I doubt all cylinders are misfiring but if they are the plugs will need to be replaced.

Macster

There are misfire codes for all cylinders. That strongly suggests all are misfiring. It is not like the engine controller to flag misfires if they are not actually happening. Now I admit there have been rather rare cases where misbehaving cylinder or cylinders can affect adjacent cylinders (or cylinders on the other bank) to the point they misfire -- that is fail to deliver the expected acceleration to the flywheel during their power stroke (which is what a misfire is). Could this be the case with the OP's engine? Maybe.

There are exceptions, but generally I'm not a fan of pulling plugs, which suggests they will be reused.

For instance, a plug or more might be say wet with fuel. But is this a sign of too much fuel pressure? A leaking injector? Or just the result of someone using too cold a plug? Or just a bad plug? Or bad coil? A loose plug wire? A loose coil connection with the engine harness?

I would be more in favor of replacing the plugs -- which has the old plugs out and available for study -- and carefully stored so one knows which cylinder which plug came from -- for whatever this is worth -- and maybe replacing coils if any shows signs of deterioration. (And unless the coils are very new and the bad coil is just due to premature failure I'd replace all coils.)

Also, it is critical the new plugs be the right plugs. (And less common but the new coils be the right coils. I am not a fan of aftermarket/OEM coils I prefer the real thing.) I recall on another forum a Cayman owner reported similar misfire behavior and it turned out the new plugs were just not the right plugs even though the plug manufacturer's reference indicated the plugs were comparable to the plugs recommended by Porsche. In the engine this proved to *not* be the case.

For knowing what's going on I prefer to use the error codes: My Boxster OBD2 error code (including some P1xxx errors) references are gone but I recall the references I had provided good info on trouble shooting what might cause the problems.

Then using the error codes and engine telemetry to try to get to the bottom of the problem.

Danny Buonsanto

Changing the coils and plugs did not work. Old Plugs looked normal and tips were still in good shape (I still changed them) . Same codes came up. Some suspect its the Crank Shift position sensor. Also possibly Idle Control Valve gasket or a dirty Throttle body. Any other thoughts? I hate to keep guessing and gambling changing parts out but maybe that's what I have to do until its fixed...Battery is good..once the car is on, it runs and feels normally. Doesn't run rough or hesitate and I use Premium gas always. I was told its not a mechanic issue but rather an electronic issue so its most likely the CSPS next on the list...