clipod

Hi Everyone,
I have a boxster 01, 5 speed manual, 70k milage. I got it from a person who sold it around 64K. I did a 60K service on it.

This is my first car so didnt knew much when I brough it. After I brought the car I noticed that around 3000 RMP it shakes. So after some research changed front engine mount. Also did wheel balancing too. Still small amount of vibration can be felt under my seat when the RPM is around 3000. Have the same problem when enging idles.
Recently I have been facing performance loss. I dont rev upto higher RPM's. The best I do is until 4000RPM. But I like quick accelaration from 1500-3200 so I drive just between that mark. When the engine is cold it performs good enough. But once the engine gets warmed up(when the temp. gauge stays around 200 degrees), after a while of driving it looses its performance. I dont get those quick accelearations. Also I have to step on my accelaration pedal a little more(on my top gear).
I spoke with my mechanic (JONES AUTOWERKS, San antonio,TX), he rev's upto 6000 and says it works fine. 6-7 mechanics tested that but everyone say its fine. Deep down I feel there is something wrong and would like to know.

Previously I used to accelarate between signal lights which I stopped now.

Things I felt which may be Culprits:
1)MAF sensor
2)Coolant Tank
3)Any wheel bearings which puts more effort on the engine to turn the wheels
4)Idiling the car.
5)AOS
6)Vacume leaks

Recently changed the alternator and read some where that I should not take the car for short trips. Since then I dont stop the car for short trips, so I have to idel it if there are lot of stops. Thats the only car I have so I use it for day to day purpose.

But I am not able to judge properly coz the thing happens after engine get warmed up.

Also need some recommendations how to drive a manual transmission. How much people generally rev the car before changing to higher gear. And I have this habit of pressing gas pedal a little before letting of the clutch go coz when I change gears it gives a jerk and hence wanted a smoother gear change. But the funny thing is, if I do like that then the performace is not good when compared to not giving accelaration until the remove my foot from the clutch totally. Its like the car is asking for sometime to breath....... I took it to another mechanic and he said that its because its a v6 and so its not that responsive.

Macster

Well, you have 6 or 7 mechanics that all say the car is fine... maybe it is fine?

Is the vibration present at 3K no matter the gear the transmission is in? No matter the car's speed? No matter the road surface?

A vibration that appears to be related to tire imbalance but is not affected by tire rebalancing and that appears at speed (75mph or higher is my experience) but just happens to appear at 3K (in 5th gear) can arise from the front tires being overinflated. Be sure you get a good tire pressure gage and set the tire pressures with the tires cold. Be careful to get the pressure right on the money.

If you want disconnect the MAF at where it connects to the wiring harness, then drive the car normally.

It would help if you had an OBD2 code reader to clear any codes after the MAF disconnect which resets the long term fuel trims (among other things) so the engine starts out with no remembered fueling based on the suspected bad MAF.

I do not see what the coolant tank has to do with anything, unless the engine is overheating, losing coolant.

Be sure the cap doesn't leak. One sign is water condensation under the trunk lid over the area of the coolant tank cap/oil filler cap.

While you are there be sure the oil filler cap isn't leaking. These can leak and cause error codes that can have one replacing the MAF when the cap was the culprit. (Mea culpa.)

If a wheel bearing was generating enough drag to affect the engine's ability to move the car down the road the flames from the dragging bearing would be a clue.

If the engine is down on performance when up to temp -- and assuming the engine is not overheating, that the cooling system is full, has no pockets of air, and the cooling system is able to hold pressure -- one suspect is the air intake temp is wrong, too high, and the engine is receiving less fuel than it should.

This is in the MAF, so the test above where you disconnect the MAF will help you determine this.

Another possibilty is the fuel filter needs to be changed, or the fuel pump is weak, or to put into more general terms there's a fuel supply/pressure problem.

If the AOS were leaking, or if there were any other leaks, I think you'd have seen the CEL come on.

Oh, you have verified the CEL comes on when you turn on the key and goes off when you start the engine?

Short trips are 'hard' on the engine cause of unburned gas and water build up in the oil. More frequent oil/filter services are advised.

Short trips are also 'hard' on the battery because the car is not driven long enough for the alternator to replenish the battery after the start.

You can use a battery charger/maintainer but another trick and more fun, is to once in a while take the long way to work, or home, or both and put 30 or more miles on the car.

How to drive a manual? I really can't help you as I have driven one so long it comes automatically to me so much so that I can't recall the process.

Basically the engine will tell you what it likes. What I have found is with the engine cold -- not up to full operating temperature -- is to upshift before 4K and better is upshift under 3.5K.

Avoid using an idling engine even in 1st gear to keep the car moving. Oil pressure when hot is at its lowest at idle and this provides less protection against higher loads.

Keep revs above 1K in 2nd gear and above 1.5K in 3rd, and above 2K in 4th/5th. If in a higher gear you want hard acceleration downshift.

The above is not cast in stone, for I have found within reason my 02 Boxster is very tractable in 4th gear under 1.5k rpms.

Practice makes perfect so drive the car more.

(This assumes -- and I think one of the mechanics would have found this -- the clutch is engaging properly, is not worn out, grabby, hanging up, etc.)

Also, FWIW, I have found moving the seat back a bit further than I normally like to sit which causes my left leg to be more extended improves my working of the clutch.

Sincerely,

Macster.