1999 996 starting problem

[mathwiz579]

I've been having a starting issue with my 1999 996 (about 95,000 miles, automatic) since mid-November. Sometimes the car will start up just fine. Other times, with no rhyme or reason as to timing (sometimes cold start in the morning, sometimes warm start after car has been parked for 30 minutes to a few hours, etc.) the car does not want to start up. When I turn the key I will hear the "na na na na na" sound which could last up to 10 seconds or so. Then sometimes the engine will fire up and die right away. Eventually, after repeated starting attempts, the engine will start up. Otherwise, the car drives just fine.

Yesterday, had a new symptom pop up. Was trying to start the car and then heard a "boom" behind me and white smoke coming from the engine compartment. No fire. Let the car sit for 5 minutes and eventually got it started.

Car has been taken to multiple mechanics who either (1) can't replicate the starting issue after numerous attempts; or (2) have the issue but can't figure out what it is. First time around, Porsche mechanic (independent shop) was able to recreate the issue once and told me that fuel pump needed replacement. After replacing the fuel pump, problem still happened. Next time around at a different Porsche shop (dealership), mechanic could not replicate the starting issue, did a full inspection of the car, and told me that the ignition coils needed replacing because of hairline cracks so we replaced all the coils as well as the spark plug. Problem continues.

Any thoughts would be appreciated. I've dumped close to $2000 on repairs between the fuel pump and ignition coils and don't want to do any more repairs until someone can tell me the problem.

Thanks much!

[Ronnie38]

Did you wash the care just before the problem started?

If not then, just guessing, but try clean the MAP, and check or replace the fuel filter.

[JFP in PA]

I've been having a starting issue with my 1999 996 (about 95,000 miles, automatic) since mid-November. Sometimes the car will start up just fine. Other times, with no rhyme or reason as to timing (sometimes cold start in the morning, sometimes warm start after car has been parked for 30 minutes to a few hours, etc.) the car does not want to start up. When I turn the key I will hear the "na na na na na" sound which could last up to 10 seconds or so. Then sometimes the engine will fire up and die right away. Eventually, after repeated starting attempts, the engine will start up. Otherwise, the car drives just fine.

Yesterday, had a new symptom pop up. Was trying to start the car and then heard a "boom" behind me and white smoke coming from the engine compartment. No fire. Let the car sit for 5 minutes and eventually got it started.

Car has been taken to multiple mechanics who either (1) can't replicate the starting issue after numerous attempts; or (2) have the issue but can't figure out what it is. First time around, Porsche mechanic (independent shop) was able to recreate the issue once and told me that fuel pump needed replacement. After replacing the fuel pump, problem still happened. Next time around at a different Porsche shop (dealership), mechanic could not replicate the starting issue, did a full inspection of the car, and told me that the ignition coils needed replacing because of hairline cracks so we replaced all the coils as well as the spark plug. Problem continues.

Any thoughts would be appreciated. I've dumped close to $2000 on repairs between the fuel pump and ignition coils and don't want to do any more repairs until someone can tell me the problem.

Thanks much!

It is extremely difficult to correctly diagnose a problems with such sparse information. I would assume the car threw codes when all this was going on, did you get the codes? At a minimum, you should have the car scanned with a Porsche specific system (PST II, PIWIS, or Durametric), collecting data on any active or pending codes, as well as fuel trims when the car is running. I would also check the car's fuel pressure and delivery rates. We need more factual input before even hazarding a guess as to what is going on.................

[mathwiz579]

I don't have a code reader at home and throughout the entire time this problem has been occuring the check engine light has not come on, so if any codes are being thrown they are soft codes.

[binger]

I agree with JFP, Its hard to help with out any proper data. Soft codes or not it will give all of us a direction to point you in. Also what scan tool are you using?

[mathwiz579]

Thanks for the input thus far. I don't own a scan tool so do not know what codes if any are being thrown. Was hoping I could get some ideas on this forum on potential causes to the problem without more data from the car. At this point with two different porsche mechanics telling me they can't find the problem I am considering just trading the car in.

[binger]

Without anymore info you can not correctly diagnose your issue without throwing "wasting" more money at it. Your in San Diego? I would look at the renntech tool registry to see if anyone near you can scan your car. see the link below.

http://www.renntech.org/forums/topic/21656-pst2-piwis-durametric-tool-registry/

[Jeff Diffenderfer]

Howdy,

 

I've just gone through a similar situation with my 1999 996 C2, and discovered the clutch pedal switch actuator (2' long bent metal bar that presses against the micro switch) needed to be opened up a bit.  It's a gray switch and is mounted at the rear of the clutch pedal stem.

 

The symptoms were finally clear to me when I pressed the clutch all the way to the floor and the car started consistently.

 

Hope this helps

 

Drift

[Hilux2400]

Is it cranking at normal speed, or is it a slow turnover?  The battery is 12v but when cranking its voltage drops because of load. If the voltage drops below a certain point there is insufficient power remaining to deliver a spark.  Before you spend any more on big stuff, do a few basic things:

 

Is your battery in good nick?

 

Is the starter motor drawing too much current and leaving nothing for the essentials of a spark and fuel delivery?

 

Is there a good earth between the battery and the body and between the engine and the body?

 

Is there a good +ve connection between the battery and the starter solenoid post. 

 

I was surprised when I checked the engine earth strap on my 996, just how bad an earth was available.  This is quite a simple job, but best done with the back wheel off.    

[Ahsai]

Guys, this thread was 2yrs old :)

[Love_my_P_Car]

Guys, this thread was 2yrs old :)

 

Hopefully the car hasn't been sitting since the post was made  :lightbulb:

[Hilux2400]

Sorry - missed that

H