MAF failure or...?

Went for a drive today about 60 miles long. After stopping and getting back on the road, upon putting the car into first gear and trying to drive the engine sputtered some, I would give it gas but RPMs weren't moving. Then the engine caught and I continued on. A minute later during the drive same thing happened in 3rd gear, driving along and giving it gas but no go and the RPMS dropped. Happened about 4 times and just stopped the vehicle to get it towed. Is this an issue with MAF or something else? 60k miles 996 6 speed. Thanks

I should mention there were no check engine lights etc. based on a search it looks like most MAF issues are accompanied by CELs.

Or a bad coil pack?

Coil packs... Especially if there were wet conditions or just washed the car. This happened to me when I first got mine. I washed the car 3 times in between doing some slight paint correction. I used a lot of water when doing so and lots got in the engine compartment. When I had it all shiny and pretty I jumped in it and took off down the road and it coughed and sputtered horribly the first mile or two. Very scary. Then stopped and ran fine. Shortly after I replaced spark plugs, tubes and coil packs.

Ok thanks. Only thing is the coil packs and plugs were changed less than 10k miles ago. I did wash it yesterday and it rained a little today.

It sounds like from the responses that we should never drive our cars either after being washed or in any inclement weather. That's total hogwash! These things are durable as anything and I drive my car in all sorts of torrential rain, and it has never done that. First rules apply - air, spark and fuel. You are looking for something that is common to all cylinders and a general loss of power. A bad MAF will usually throw a CEL, and it is a good idea to pull it, clean it and see what happens. A bad coil will only affect one cylinder and will also throw a CEL with a code for the particular cylinder affected. You said there was no CEL. Another thing common to all cylinders is fuel pump/fuel filter, so that is going to have to be checked out. BTW, have you noticed anything strange electrical? Sudden drop in voltage? I would disconnect the engine ground strap and clean the connectors both ends. That would affect the entire engine as well.

Thanks for the replies. There have been no odd electrical issues noted. The only thing I recently did was change the air filter. No other very recent work has been done. Oil change 3 months ago. Battery 9 months ago. If no check engine light came on then presumably no error code will be able to be read, is that correct?

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With the proper equipment, an OBD2 code reader, you can check for any pending error codes. I don't think you'll find any. The behavior suggests a failing fuel pump.

+1 for the fuel pump or a very clogged fuel filter.

I had similar symptoms but had CELS for misfires. cyl 1 and 4. new MAF fixed my issue

My Indy has been unable to replicate the issue even after driving it a long time. Said the car pulls strong and feels good. No check engine light and no error codes when they connect diagnostic tool. The fuel pump does not seem to be the issue. Starting in 2002 I believe the fuel filter is part of the fuel pump (or else just sits inside the gas tank and needs to be replaced along with fuel pump) so that has been ruled out. Indy is not too keen on cleaning the MAF. He is suggesting changing the gas pedal, have not really seen this as the culprit in any of the forums. Has any one heard of the gas pedal or any switch that comes along with the gas pedal causing intermittent throttle issues? He said it happens with the early versions of e-gas. I did find a Cayman post who had intermittent throttle hesitation and it was resolved using a brake switch - https://rennlist.com/forums/987-981-...-cayman-r.html At this point I may just get the car back and do nothing and see if the issue recurs. It's my second car and I'm really hoping to diagnose the culprit before throwing funds at it with limited certainty.

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Well, I'm probably repeating myself but bear with me: No CEL. No active error codes. No pending error codes. Doesn't read like a MAF or a COIL or even a throttle. In the case of a MAF or COIL or throttle problem almost certainly there would be a CEL and one or more active codes, or if no CEL a pending code. Thus it is my belief it is a fuel supply problem and this most often is a bad, could be intermittently bad, fuel pump. A bad fuel line in the tank is also a possibility. Do you per chance own a Carrera 4 model? If so these have a weird fuel tank setup. I won't go into more detail unless you actually own one. Even if you do not own a Carrera 4 model if a fuel line in the tank has a crack/split this can under some conditions allow fuel pressure to momentarily drop and the engine will act as you experienced. There can be no CEL as there is no emissions related behavior detected. However, I can't with sufficient confidence say it is a bad fuel pump or a bad fuel line in the tank to then suggest you have these replaced. I could be wrong of course. I will add I do not think it is a dirty MAF. MAF's in cars with stock air filtration systems and in good repair -- with no holes/tears in the filter element and no cracks or air leaks in the intake system either after the filter and before the MAF or after the MAF -- remain clean for 100,000's of thousands of miles. If you are so inclined and are capable of it without any chance of doing any harm to the MAF, the engine wiring harness, or the DME to which it connects, you can clean or have cleaned the MAF. I don't think it will help, though and is a waste of time. If you do clean the MAF do so over clean white paper towels to catch the run off. If you see any significant signs of dirt in the cleaner fluid then there is another problem. The intake system is letting unfiltered air in ahead of the MAF. (If unfiltered air were coming in after the MAF the MAF would not be dirty and there would be almost certainly a CEL and one or more error codes.) If you want next time you have the car out and are back home and the engine is fully warmed up with the engine idling open the engine compartment. Be careful. The engine compartment fan can come on at any time so keep your fingers/hands out of the fan enclosure! Try to move the oil fillter tube cap. Push it side to side or pull up on it. Pay attention to the engine. If the engine reacts then the oil filler tube cap is leaking. Believe it or not I have had to replace the one on my Boxster now twice. I get around 150K miles out of a cap. The car has over 302K miles on it. In my experience the leaking cap caused a CEL and error code pointing to a fuel mixture problem was logged. The leaking cap never had any apparent effect on the engine above idle speed. But if the cap is bad -- big if -- in your car's case it might just cause a momentary air leak when taking off with the engine speed not much above idle.

Thanks Macster. It is a C2 Cabriolet. It is currently at my indy. They, like you, are against cleaning the MAF. They also don't think it's the fuel pump (isn't there a way to check this by screwing on a meter to test pressure? I trust they've done it but next I talk with them I'll verify). I am having them try the brake switch I posted in the above trail ($20 part). Their recomendation was actually to change the gas pedal assembly. I have not seen much about that on any of the forums but do trust their experience. That's a $300 part. Since it's intermittent and no CEL's, I'm trying to diagnose with more certaintiy. I'll give the oil cap a shake - should I take the oil feeder tube out of the assembly that holds it (like when I change the air filter) or just leave it in the clamp that holds it? Do you have a part number for the oil cap? All I can find online is a Billet one. Thanks a lot.

I found part # 996-107-035-52-M100 which seems to be the oil cap.

And 996 107 035 50. Only problem is that this problem occurs when driving at speed - even at 30 to 45 MPH. Sounds like this issue may have an impact only at idle, based on the thread above.