Boxster 2002 hesitates
 

I have a 2002 boxster, just bought it. It's done about 30 000miles.

When accelerating the engine hesitates, it seems to loose some power above 3000 rpm, and it gets kinda jerky around 4000rpm.. No CEL light has come on.

Any idea what this can be? Fuel filter, MAF, O2 sensor?

I'm no mechanic, so help is much appreciated :)

I forgot..
 

Over the last year the car has been standing in a garage most of the time. The last owner almost haven't driven it..

fuel
 

bad fuel first guess

+1 on the old fuel..
Does the CEL light come on when you turn the key on? (Light check)
Some have had that light removed to mask it for resale.

And have you had the codes read because there may be some there even though the CEL isn't on. I'd like to see what some good injector cleaner and a new tank of gas would do.

There are so many things it could be, but the first step should be to read the codes as that might point directly to the problem.

Water/frozen water in your fuel system is another possibility.

Many of us have code readers. Where are you located in Norway?

Perhaps one of us is nearby could help check your codes.

After you have gotten fuel out. Add Fuel Injector cleaner and run for at least half a tank. Then, check the intake including Throttle Body and "T"s, including intake manifolds. Probably some yuck in there as well.

Good luck!

If any of the above suggestions don't work. Try cleaning the MAF. My car had the same problem, changed the MAF and all is well. You can just unplug it and take it for a ride. If it performs much better then you might have a bad or dirty MAF. I tried to clean mine first, but it didn't help. So I got a new one. You will get a CEL when you unplug it, at least i did.

This sounds similar to the problems I had with my 1998 Boxster. I think the initial problem was the ignition coils, then things got really bad as i think the misfire contaminated the o2 sensors.

I agree with previous comments about getting a fault code reader on it. If you read the live data it should tell you if there is a problem with your sensors. Look for STFT and LTFT readings. They should be similar for both banks of cylinders and change between +% and -% depending on load. Sensors are easy to change provided they are not rusted in!

My experience of a failing MAF on two other cars was that it caused a general loss of power rather than misfire.

I have also had problems with old fuel and cured it with a fresh tankful and some injector cleaner.

Good luck. Be interested to know what the problem was when you have solved it.