Will not Start

[drewlj]

I have a 99 Boxster w/ an automatic trans. When I go to start it nothing happens.

All of the instruments are working properly. Here is what I have fixed so far.

1st - a new starter

2nd - a new ignition switch part # 4A0-905-849-B-M5

3rd - a new battery

It ran fine for a few day and then all of a sudden it decided not to start again with no warning.

Everything seems to be ok, but when I go to start the engine - nothing: no clicking, no trying to turn the engine over etc.....

I have checked the fuses all of which seem fine. It is almost as if the starter is not receiving any electricity.......

I am stumped and clueless. Is there a relay somewhere I should check or a sensor that is telling the computer not to start?

I have read some post about the mass air sensor, but would that prevent the car from starting?

Thanks

:lightbulb:

[beety]

Hi there,

could you answer a couple more points about the problem to help people diagnose?

(i) do the diagnostic bulbs light on the dash when the ignition is turned during the problem?

(ii) have you got more than one set of keys you can try e.g. the transponder coil may be broken to deactivate the immobiliser?

One immediate thing you could check is the main earthing points on the car are clean and well connected.

[drewlj]

Yes the dummy light bulbs on the dash come on.

Unfortunately I only have one key...... There is something in the key that could keep the car from starting? Could you please elaborate...

What are earthing points???

Thx

[Loren]

Does the cluster display show the car is in Park?

If not the sensor in the gear shift may have slipped off.

[beety]

If the dummy lights on the dash come on - then it looks like the electrical system is okay - seems more likely a security issue e.g. your engine immobiliser is not happy with the keyfob and is blocking supply to the starter etc. Was just if you had bad earths, this leads to battery discharge and low vehicle voltages in various circuits.

Porsche keys have an inductor which has a stored code inbuilt - this is picked-up by a coil wrapped around the ignition barrel, the immobiliser will only allow the car to be started if the code matches that in the security unit (under passenger seat).

[RFM]

Hi

It looks like the tiptronic switch upon the gearbox is faulty, the D.M.E. control box think that a gear is engaged and refused too start the engine. Problems with the key transponder are infrequent.

[RFM]

The switch on the brake pedal is also a possibility, he have a double function - activate the brake lights and start interruption.

[drewlj]

OK Monday update after not wanting to start for the last 48 hours......

• The diagnostic dash bulbs illuminate when trying to be started
  
• The dash shows that the car is in park
  
• There is no sign of battery discharge
  

1. What are earthing points? Grounded wires?
   
2. How do you check the triptronic switch?
   
3. How do I check the brake pedal switch?
   

When I put the key in the ignition with the drivers door open it chimes that the keys are in the ignition. So it is not the ignition switch.

When I disconnect the battery and let it reset the computer the car starts right up.

Also when it sits for a few days it spits and sputters upon starting as if it is fuel or air starved.

Officially stumped at this point............ Something is telling the computer not to start the engine........

:soapbox:

[drewlj]

OK Monday update after not wanting to start for the last 48 hours......

• The diagnostic dash bulbs illuminate when trying to be started
  
• The dash shows that the car is in park
  
• There is no sign of battery discharge
  

1. What are earthing points? Grounded wires?
   
2. How do you check the triptronic switch?
   
3. How do I check the brake pedal switch?
   

When I put the key in the ignition with the drivers door open it chimes that the keys are in the ignition. So it is not the ignition switch.

When I disconnect the battery and let it reset the computer the car starts right up.

Also when it sits for a few days it spits and sputters upon starting as if it is fuel or air starved.

Officially stumped at this point............ Something is telling the computer not to start the engine........

:soapbox:

[liifesfun]

Hi

Sugestion - as it is a tiptronic - as a saftey measure it will only start in Park or Neutral, try moving the gear shift in or out of gear and see if this changes the situation. I dont know this from experince just applying logic and supporting previous comets on the Tiptonic switch which is dependent on gear shift position.

RE the brake switch - do the brake lights work?

I dont know the specifics of the boxster but can hep a litle with education.

Earthing points - cars electrical systems are DC (direct current) which means they have a +ve and -ve voltage which you see as the poistive and negative on the battery, most cars inc boxster use the negative as an earth, that menas the negative terminal has a connection to the chassis or body of the car, this saves running 2 wires to points in the car that need electricty, hence you will see around the car wires quite often black with a brass round connector that has a screw through it and is screwed into a metal point of the car these are the earthing points, does that make sense.

Generally these earth points are considered to be 0 volts, the positive is considerd as 12 volts.

[insite]

this will sound wierd, but when the car is not starting, can you turn your radio on? i ask because one part of the ignition switch that allows the starter to turn over is actually a little button that is pressed by your key. if the ignition switch was not properly tightened when installed, it can back away from the ignition lock so that the button does not get fully pressed. this will prevent the car from starting. it will also prevent your radio from coming on.

if that's not the problem, does your car have a factory alarm?

[drewlj]

Yes, both the radio and the brake lights work. I haven't tried moving the transmission shifter as I have been out of town. The next time it decides not to start I will try this before I reset the computer.

Thanks