2005 Porsche Boxster would bog down in 1st and 2nd gear

[gfrnndz]

I have a 2005 Porsche Boxster that I bought used almost a year ago and noticed this problem. When I am in 1st gear starting out from a complete stop, sometimes the car would bog down. I would press the gas but no acceleration would occur. The engine does not stop. When I press the clutch down, I can rev the engine and get the car going. This also happens sometimes when shifting into 2nd. I don't think I'm accidentally shifting to 3rd instead of 1st or 4th instead of 2nd by mistake. Could the problem be that I'm not reving high enough when starting out in 1st or the rev is not high enough when shifting to 2nd? The car never bogs down otherwise. The car drives fine when in 3rd, 4th, or 5th gear. This problem does not occur all the time but it is starting to get annoying and I'm scared it might happen when I'm trying to merge into traffic.

Thanks for any help,

[Hilux2400]

Sounds like your clutch is slipping and on its way to complete failure.

In a car with a manual gearbox, when it is in gear and the clutch is engaged (foot off pedal), the car should move forward when power is applied. If power is applied and the car does not move, it means that the clutch does not have any bite.

In the other higher gears, when you press the gas pedal does the engine speed rise without a corresponding increase in vehicle speed?

[gfrnndz]

When it bogs down, the car engine does not rev up. The clutch does not appear to be slipping. If it were slipping the engine would rev higher but the car not move. When it bogs down at 1st, I have to press the clutch down and then I can press the gas and the engine revs and I can release the clutch and the car goes.

[wvicary]

This might sound odd but you aren't accidentally touching the brake pedal when this occurs?

[gfrnndz]

I don't think I am. Yesterday, I started to rev it more before releasing the clutch when starting in 1st and it seemed to help. It did not bog down at all.

[gfrnndz]

The car stopped accelerating again on the interstate while cruising about 70 mph. When I pressed the gas pedal to pass another car, the car would not accelerate but was actually slowing down. I was able to get the car accelerating again by pressing the clutch down and pressing the gas. Does anyone know of any problems with the throttle (gas pedal) on the Boxsters? The engine does not stop running. It almost feels like the throttle quits working until I press the clutch then it starts working again. Very strange.

Thanks for any help,

Gilbert

[JFP in PA]

These cars have an electronic throttle set up, so it is often hard to access what the actual outcome is of a physical depressing of the pedal. The system uses a potentiometer on the pedal to send a signal to the DME, which responds by moving a servo motor at the throttle plate. Either could be the source of the issue, but because they are both expensive, you need to run diagnostics to determine what is going on. Best first move would be to hook the car up to a Porsche specific scanner (PIWIS or Durametric) and look at the actual throttle position data in response to throttle pedal movement. You can also scan the car for pending codes related to the egas system at the same time.

[gfrnndz]

These cars have an electronic throttle set up, so it is often hard to access what the actual outcome is of a physical depressing of the pedal. The system uses a potentiometer on the pedal to send a signal to the DME, which responds by moving a servo motor at the throttle plate. Either could be the source of the issue, but because they are both expensive, you need to run diagnostics to determine what is going on. Best first move would be to hook the car up to a Porsche specific scanner (PIWIS or Durametric) and look at the actual throttle position data in response to throttle pedal movement. You can also scan the car for pending codes related to the egas system at the same time.

Do you know if this is a common problem with Boxsters? I plan on taking it to my local porsche independent mechanic to have it checked. When you say expensive, how expensive are we talking about?

Thanks for your reply,

Gilbert

[JFP in PA]

These cars have an electronic throttle set up, so it is often hard to access what the actual outcome is of a physical depressing of the pedal. The system uses a potentiometer on the pedal to send a signal to the DME, which responds by moving a servo motor at the throttle plate. Either could be the source of the issue, but because they are both expensive, you need to run diagnostics to determine what is going on. Best first move would be to hook the car up to a Porsche specific scanner (PIWIS or Durametric) and look at the actual throttle position data in response to throttle pedal movement. You can also scan the car for pending codes related to the egas system at the same time.

Do you know if this is a common problem with Boxsters? I plan on taking it to my local porsche independent mechanic to have it checked. When you say expensive, how expensive are we talking about?

Thanks for your reply,

Gilbert

Not common, but not unheard of either.

The throttle body is about $300 or so at retail, the throttle pedal potentiometer is in the $100 or so range. You need to know which one is the problem before swapping out parts.