dtsol

Hey All,

First-time Porsche owner, and am loving my 2005 Boxster S. As I'm getting used to the car, I'm starting to wish it accelerated faster, and am wondering whether my car is typical or if something needs to be addressed on it.

What I notice is that it is seems more responsive to the throttle when it is cold than after it has been up to temperature for a while--maybe after driving 15 minutes or more with the temp gauge at dead middle. I also notice a change in the engine sound once I've been driving at temperature for a while--it sounds less "tight," if that makes sense.

(I know my engine is a replacement engine based on the "AT" in the engine number: M96/26AT62665012, and I think this number means it's an '06 engine.)

Just wondering if anyone else has experienced this type of performance change once the car is up to temperature, and if so, how did you address it? Also wondering what would be the least complex way to improve acceleration.

Thanks!

Macster

First thing that comes to mind is the car is used. So what services could it be needing that could account for the large drop off in performance which is not normal (assuming your observations that this is occurring are right).

As an aside I have noticed my cars perform a bit better in some climatic conditions. Cool dry air is better than hot humid air. But the differences are not earthshaking and not enough to have me worried.

Anyhow the car is new to you.

What about the plugs? Engine air filter? Fuel filter?

Which reminds me: Maybe I'm getting ahead of myself. What about the fuel in the tank? Have you driven the car enough to go through a tank or two of gasoline and are you using a top tier gasoline of the proper octane grade and buying from a busy station?

The temp gage is not very good for monitoring coolant temp so unless the car is overheating severely you might know the engine is running hotter than usual.

Do the radiator fans come on (with the A/C off)? If one (or both) fail to come on the coolant temp can climb and this could cause a drop off in performance.

Even if the radiator fans work ok check the radiator ducts for a large amount of trash. The radiators have a large over capacity but even this can't make up for a horrendous amount of trash interfering with air flow through the radiators.

Yet another thing to consider is the engine compartment is rather enclosed and not well ventilated, at least compared to a front engine car. Thus among other things the intake system gets hot. This can heat the incoming air and could affect performance.

I note this possibility when after driving around town or at slow speeds in warm to hot weather that it can take some time at higher speeds for the intake too shed some heat and for the intake air temp to drop to close to ambient (I have monitored this).

Even so the Boxster (and Cayman) engine air intake is at a location that for better or worse -- mainly worse -- is going to pull in air some of which is heated after passing through the radiator. As a result intake air temp is always above ambient by at least 10 or 12 degs. F. and in some extreme conditions can be 30 or more digs. F. above ambient. Hint: If you hear the engine compartment fan come on engine compartment temperature is IIRC 135F.

Before you go crazy eliminate old/stale or wrong gas from the equation. Consider switching brands.

Get more familiar and acclimated to the car.

At the same time try to learn what (if any) services are due. Be aware that say even if the plugs were changed recently the previous owner might have had this done someplace where the wrong plugs were used. Unless you have paper work that states when this was done, where it was done, and what plugs were used...

Right now the least complex way to improve acceleration is to use more throttle. Even my 02 2.7l Boxster at full throttle and snappy shifts will have the car going down the road at illegal speeds in no time. With more space and less concern for the authorities triple digit speed does not take that long to arrive. The car, the engine, pulls like a mini locomotive. (And with over 265K miles on the engine too.)

Schmidts Cat

My feeling is, when the car is cold, it feels and sounds "tighter". Once it is warmed up, it gets smoother and quieter, and therefore FEELS less powerful.

dtsol

Thanks for the thoughts, Macster--it's not a fuel quality issue but could be something with the radiator system--I'll look into that. Schmidts Cat, what you're describing sounds like what I'm experiencing. I haven't really developed a sense yet of what "normal" is for these cars, but I would definitely like it to accelerate faster when I really step on it. I do a lot of mountain driving--I wonder if altitude might be a factor?

Schmidts Cat

How high in the mountains?

Macster

A very good question.

I recall my 96 Mustang GT which ran real well at lower altitudes becoming positively anemic at much higher altitudes in one memorable instance on I-70 at one of the higher passes.

In another instance with my Boxster I pulled onto the freeway in Colorado Springs and just happened to pull along side a Saab Turbo. We both nailed the throttle and the Saab ran away from my Boxster. (Turbo charged cars are sweet at altitude!)

dtsol

The elevation of much of my typical route is around 2,500 to 3,000 ft, and mostly twisties. (You couldn't ask for a better commute if you like to drive!)

Schmidts Cat

Sounds like that could very well be the issue...??? Turbo kit?

fhp911

ALSO -- do you rev it up?? The S motor really comes on the cams at 5k+. At what revs do you shift, and how much throttle do you give?