Bobroham

Hello everyone,

I recently purchased a 2003 boxster w/ 65k miles in very good condition.

I noticed that the CEL comes on when the engine is pushed near redline. The code is cylinder 1 misfire.

At one point in a long trip (after passing with RPM 6500-7k), I had multiple codes go off, for cylinders 1, 2 & 6.

There is also a strange smell from the exhaust (smells kind of like brakes) which causes me to think it may be the cat converter.

-First thing I did was change the sparkplugs.

-I switched the ignition coil from cylinder 1 to cylinder 2. Still having the same problem.



Any suggestions appreciated.

extanker

it seems you have covered the most common things....plugs/coil swap. have you run through the gas tank yet........water in fuel can cause high rpm miss. you may need to get a good scan tool on the car,one with a flight recorder mode that can capture data at miss. get a good look at crank/cam sensor data ,02 sensor at WOT

Macster

Any other error codes, any pending error codes, besides just the misfire codes?

It is important to when switching the coils around to double check the coil/wiring harness connector/connection for any signs of issues. The coil's connection to the wiring harness is just as important as its connection to the plug.

The smell or odor could be the converters and they can get off on the wrong foot chemically speaking due to stale or bad gasoline. If the gasoline is stale enough to affect the converters it can also affect the engine, possibly explain the misfires.

This then prompts the questions: How fresh or not as the case may be is the gasoline? Is it of the proper octane grade?

The engine requires 93 octane but in some areas 91 is all that is available. Still I have never seen either of my Porsches misfire at high RPMs or manifest any real issues with just 91. But they both get only fresh 91.

I note the car is new to you. While I'm sure the car is in good condition the engine (and injectors) may be suffering from engine (injector) deposits build up.

My advice would be to run a bottle of Techron through the gas tank. Use according to directions on the bottle's label. The general advice is if this helps to use a 2nd bottle. IOWs, repeat the "treatment".

Afterwards it is advisable to change the oil/filter to remove the oil that is now contaminated with the remnants of the Techron.

Just some general thoughts: The engine oil is of the proper type/viscosity (multi) grade, reasonably fresh, and the level is good? How does the engine air filter look? Is the filter element installed correctly with no gaps or tears?

IIRC the 2003 MY doesn't have a servicable fuel filter. It is part of the fuel pump housing and intended to last the life of the pump.

If after ensuring the gasoline is fresh and after using Techron if the misfire still is present then you have to consider the injector as a possible explanation. It is unable to "keep up" at high RPMs high duty cycles and as a result doesn't provide sufficient fuel in the time allotted and the cylinder misfires.

Just a warning, not intended to scare you, but just to make you aware: If at any time the engine starts to act up at other RPMs, make any noise, in any way signal all is not well and its condition is deteriorating shut off the engine as soon as it is safe to do so and do not try to restart it until you have had it flat bedded to a qualified Porsche shop for evaluation.

However, I don't think anything of the sort will happen. If fresh gasoline, Techron don't help I think you'll find the injector is weak.

pbastian

Don't want to be an alarmist. But, my '00 Boxster had cylinder misfires shortly before what was likely an IMS fail. I am not experienced enough to say that the two are definitely related. But they did happen in close succession. Just curious - has the IMS upgrade been done on your '03?

Bobroham

Thanks for the reply.

I am currently running some PetroCanada fuel injector cleaner (our equivalent to techron). Half way through the first tank and will do another.

I am currently running 91 octane and I get 93/94 when I can find it. I only buy gas from Esso/Petro Canada which are both rated as high quality gasoline.

Macster

Got my fingers crossed the fuel system/injector cleaner works for you.

I always prided myself on my usage -- very few short trips and using a name brand and top tier and fresh gasoline (Shell) -- to keep the fuel system/injectors/engine free of deposits. I liked to state I preferred to keep the fuel system/injectors/engine clean "organically".

But I got an eye opening (but pleasant) surprise when because the local Shell station raised its prices nearly 10% higher per gallon than nearby stations (name brand and top tier in their own right) and I switched to Chevron after a few tank fulls my 2002 Boxster engine perked up some.

It seems a fuel system/injector cleaner is needed occasionally. So once a year I'm going to run a bottle of Techron through both of my Porsche engines just prior to an oil/filter service.

Byprodriver

986 fuel pumps are getting old to, test fuel pressure if the problem persists.