Boxster won't restart at running tempurature

[blake986]

I have a 1998 Boxster 2.5L and have owned it faithfully for nearly 100,000 Kms. It now has 160K on it. It nearly left me stranded for the first time recently.

Here is the issue:
The car starts perfectly when it is cold. It usually only requires a few revolutions of the starter for the engine to fire.

Upon getting the car to full running tempurature and shutting the engine off -leaving the vehicle for 1 hour or 2, the engine will not restart when wanting to continue my trip. The engine is around 40-50 degrees at this stage, and I could keep turning over the engine until the battery dies (seemingly) with no response from the engine. Letting it cool further results in a car that will start.

Initially I thought it may be a fuel pump or a fuel pressure regulator that was on its last legs, but reading up on some forums it seems that it may actually be a crank position sesor or cam position sensor.

Has anyone experienced these symptoms and fixed it successfully?

Many thanks!
Blake

[steveng1993]

I have had other non porsche cars that have had this problem and it was a coolant temperature sensor. But I have also read about the crank sensor going bad too.
I would think that if the crank or cam sensor was bad it would probably throw a code.

[JFP in PA]

Originally Posted by steveng1993

I have had other non porsche cars that have had this problem and it was a coolant temperature sensor. But I have also read about the crank sensor going bad too.
I would think that if the crank or cam sensor was bad it would probably throw a code.

Not really, the crank position sensor can fail without the DME sensing it, and when the DME sees no crank rotation, it turns off the fuel assuming the engine is not running. Common problem that is often hard to diagnose.

[chamilun]

crank position sensor

[blake986]

Thanks for your suggestions.

A Porsche tech mentioned that a failed crank sensor will typically kill the engine while it is running and leave you stranded mid-trip. Up to this point I have not had that symptom.

Interesting note about the coolant sensor. I have noticed that the coolant temp guage is not reading as it should be once the car is 'hot'. Could be a failing thermostat (replaced 50K ago with the water pump). Both were coming due for replacement anyway, but I wouldn't have thought to replace the sensor at that time too.

The tech suggested starting with the relays located in the trunk as sometimes they can get hot and stay closed once they cool down. I'll start with the DME and coil relays.

[chamilun]

cps symptoms on my 996 were start normally sometimes, then wouldnt start other times. Was
better when car was cold. but once warmed up, pretty much wouldnt fire.

so exact same symptoms as you. at the time, doing a little research found this is the usual culprit

[blake986]

I'll add cps to my list of parts to replace. It seems they are all related to running the fuel system to varying degrees.