Poor Acceleration

[Mike_howes]

I have only just bought my 1999 2.5 boxster.....Total virgin when it comes to this car.....but when i accelerate hard, when i get to between 4000-5000rpm the engine strugles and holds back......as if a limiter had kicked in yet i have another 2-3000 rpm before it hits the red line......anyone have any ideas before i start replacing parts.......top speed that i have had out of it is only 125mph.....

Regards Mike

[whereswilbur]

I have only just bought my 1999 2.5 boxster.....Total virgin when it comes to this car.....but when i accelerate hard, when i get to between 4000-5000rpm the engine strugles and holds back......as if a limiter had kicked in yet i have another 2-3000 rpm before it hits the red line......anyone have any ideas before i start replacing parts.......top speed that i have had out of it is only 125mph.....

Regards Mike

I have a similar problem with my 98 boxster. I have replaced the MAF (mass airflow meter) and cleaned the ICV (inlet control valve) which has helped a little. I also put a fuel treatment in when I filled up (I always use V-Power in my car). Also worth while seeing if your car is running any fault codes, if so post them on here and you will get all the help you need! Cheers, Dave.

[mikefocke]

Something associated with the variocam? Or the exhaust partially blocked?

But remember this is a 2.5 litre car...not a big displacement engine.

Get your OBD2 codes read. Lets make sure there isn't something obvious.

[infocusf8]

Is your Box a stick or Tiptronic? When you say you've only gotten up to 125 mph what were the circumstances? Did you try to go faster and have the room to get the car up to a higher speed? I might add that if you were on a highway that is quite dangerous and in California if you are busted for it you are arrested on the spot and your car impounded. Mike is correct in that the 2.5L is not a speed demon but the pre 2000 Boxsters were a little lighter in weight and are nimble and fast enough to keep up with more powerful cars on twisty winding roads. My '99 Tiptronic will never set an AX, drag or track record but the weight distribution does allow me to accelerate in and out of turns where faster cars have to slow down and brake to keep from losing control. When I use the Manual shift setting my car seems slow accelerating until I reach about 4500 rpm then at 6K rpm it leaps and once I hit 2nd gear on up to fifth gear the car has much better and more even acceleration but you will not reach max BHP output until you reach 6K rpm.

[fltrplntman]

I have only just bought my 1999 2.5 boxster.....Total virgin when it comes to this car.....but when i accelerate hard, when i get to between 4000-5000rpm the engine strugles and holds back......as if a limiter had kicked in yet i have another 2-3000 rpm before it hits the red line......anyone have any ideas before i start replacing parts.......top speed that i have had out of it is only 125mph.....

Regards Mike

I had the same problem with my 98. I just bought it 2 weeks ago, and I felt it nose over at about 4500 rpm. A few days later a CEL came on and the codes were evaporative in nature.

The weather finally broke and it was nice enough to remove the engine cover to take a peek. i pulled out the air filter and it was completely plugged with the foam prefilter. It broke down from age and crumbled into a fine powder. I looked at the date code and it read 98m02. Looking at it.. I think it the factory air filter.

I replaced it, and the car wouldn't run for crap... barely idled. I deduced that the ECU had adjusted itself to compensate. The new fresh air threw it way the hell off. I cleaned the Mass Airflow Sensor, disconnected the battery, waited 15 minutes, reconnected the battery, turned the key on and waited 30 seconds, then started the car.

WHAT A DIFFERENCE!!

The sound out of the suck hole in the left quarter panel is worth the price of admission.

Happy trails!!