Engine hesitation and quick CEL flash?

Hi all

I have a 2003 Boxster S with 62k miles and have been having this problem for a bit now. When driving at highway speeds (60-80mph) during a trip (but not every trip), almost always in 5th gear, the car will do a quick hiccup/hesitate, the CEL will blink once or twice for no more than a second or two, and then everything goes completely back to normal.

It doesn't do it every trip, and there seems to be no other repurcussions. The system did not throw any codes when Maurice checked it at BRBS last year. I thought it could be the spark plugs, and had them replaced last week since I needed to do that for the 60k maintenance. There were no codes, they put the new ones in, and I was optimistic, but a few days later on a 5 hour RT from NYC to DC, it did it once on the way down and once on the way back.

Maurice and Stefan have been great answering all my other questions and the mechanics can't figure it out, so I figured I'd throw it out to the larger group to see if anyone else had experienced this.

Thx

the misfire condition being transitory and the error codes going away as soon as the error condition goes away.

You can see if the symptom appears with the MAF disconnected in an attempt to eliminate the MAF as the cause. Disconnect the MAF, clear the error codes ( to reset the long term fuel trims, etc back to their factory defaults ) then just drive the car normally. The CEL might come on due to the MAF being disconnected so if the CEL does come on you can't assume it is because the original condition has resurfaced.

I do not know your region but with misfires coils are suspect (some regions are harder on the coils than other regions). I note you had the plugs changed but not the coils. This is understandable as in many cases coils can last over several sets of plugs. I would expect too whoever did the plugs would have examined the coils and advised you if their condition suggested they needed replacing.

The only time I've had a CEL on -- no blinking though just on solid -- with a hint of engine stumble -- proved to be a bad AOS. The error codes pointed to a mixture related problem too.

And I do not know how you drive the car, what gasoline you use, so your car might be a candidate for some Techron.

That is you might consider using a bottle or two of Techron according to directions to see if this might help things. It root cause of the behavior you experience with your car could just be due to some intake valve/combustion chamber deposits that are mildly interfering with combustion. If you use this stuff arrange to change the oil/filter afterwards.

Sincerely,

MarcW.

Thanks Marc, I appreciate the feedback. I'll look into all of those things.

To answer your questions... I live in New York City/Northeast. Not dedicated to one brand but always get premium gas. And as far as my driving style, because I'm in the city, it's almost always stop&go -> road trip -> stop&go. Only track use was BRBS last year. I have fun every time I drive the car, but am not super aggressive in it.

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hoppy44
Thanks Marc, I appreciate the feedback. I'll look into all of those things.

To answer your questions... I live in New York City/Northeast. Not dedicated to one brand but always get premium gas. And as far as my driving style, because I'm in the city, it's almost always stop&go -> road trip -> stop&go. Only track use was BRBS last year. I have fun every time I drive the car, but am not super aggressive in it.

Your type of driving can lead to a build up of deposits.

If you drive the car year 'round, the coils (along with the exhaust system hardware) can suffer from the exposure. Even if you avoid driving the car in the worst of the winter months in your area the higher levels of humidity can wreck havoc on the coils based on what I came across reading UK published Porsche specific car mags and then later when I visited some UK Porsche forums. In some locales over there owners were reporting coil problems (and rusting brake rotors (to the point the rotor metal would flake off the rust was so bad)) at quite low miles. While I do not think your region has it that bad you certainly have it worse than say someone (like me) who lives/drives in a region where the climate is drier.

Sincerely,

MarcW.

Hi all

Figured I'd post a wrap-up here in case people run into this problem in the future (I hate it when I'm searching for an answer on internet message boards, and find the problem I'm having, suggested solutions, but the person never comes back on so you don't know if it worked or not).

In short
- I took your suggestion and had the coils replaced
- In the 2,000 miles since, I have not had a single CEL blink or hesitation, thus, that seems to have been the culprit

Thanks MarkW and others for your help.

Jim