I'm just trying to figure out my most recent Porsche problem. I have a 99 911 automatic and, for the first time, I was stranded because it would not start. It cranks normally. I cranked it many times until the battery was going dead, but nothing. I had it towed home, and then she starts right up???? It was getting hot when I parked it. Had the temp needle on the right side of the 180 zero driving it in Tucson today. Parked to get something quickly from a store and she would not start? I did just put the factory mufflers on 2 days ago, as I was thinking of selling this car. It's just bolt-on, and I did not seem to knock into any sensors that I'm aware of. Why would it be running great, then not start, but now starting w/o a problem and running great again? I'm guessing either this car has some safety mechanism to prevent it from starting while pretty hot, or the cam sensor? Why would just towing it home make it start? haha???? I do not think it is the ignition switch. That is new and cranks normally if it starts or not. The engine turns, so the starter is engaging fine. No CEL at all. I have a Durametric, but what to check? Any ideas would be greatly appreciated. I have read many similar issues, but It's not the starter. I have gas flowing well, new plugs. Recent added the stock mufflers is all. Those mufflers next to the engine make my car run at least 10-20 degrees hotter. Could it have something to do with the heat? Runs flawlessly after she starts though? Please help. Thanks.

 

Surprised I got no replies. I hear this is a common problem....My 99 Carrera will not start when hot and today it died at the stop light. 3 hours later it started and I drove home. I put the factory mufflers on 4 days ago and the car started stalling after it heats up. The car never did this with my bypass pipes, and it ran much cooler with the mufflers off. Now it dies when it gets the needle on the 180 zero, which is also pretty common in Arizona when its over 100 degrees. Anyway, I though I may get some input here. I have heard its the fuel pump, its the fuel pressure regulator, its the crank position sensor, its the cam angle sensor......Anyone have any ideas how to test for the problem. Thanks for any help

 

Have you pulled any codes yet? That would be the first thing I do.

Secondly, you should be able to test the cam and crank sensors with a multimeter. Forgot those values off the top of my head but you should be able to find it on the net. It maybe tricky as it's heat related and intermittent though.

Another very primitive way to see if those sensors are acting up is to run the car and put a heat gun in the area of the sensor and see if car dies after heating it.

Good Luck

 

I did have one code. P1571 immobilizer BUT!!!!! That would also prevent the starter from turning. My starter works as usual. I have had my alarm seemingly intermittently go off for years now, but I really don't think it's the DME. It wont start only when fully warmed up. The immobilizer would not be related to heat as it is under the front seat where the temp doesn't really change. I guessing crank position sensor, but I'm at a loss right now.
It is directly related to heat for sure, but that can effect so many things. My coil heat shields are dirty, but should be OK. Only change was putting the factory mufflers on= more heat and registered on the temp gauge with more heat. Then she dies. 3 hours later fires up and drives normally until fully warmed up again. Then dies. I'm at a loss.

 

Has some aspects of a failing crankshaft position sensor. The engine cranks just fine but does not start, does not even misfire or make any sounds like it wants to start.

Let the car sit a while and the engine starts right up.

I've never had to trouble shoot this but some people report a "sign" this is happening is the dash tach needle stays flat while cranking.

Because emissions is not affected there will be no CEL no active or pending error code. There might be a Porsche proprietary error code that possibly (?) Durametric could obtain. I'm sure the Porsche diagnostics computer could obtain this code, provided of course, it exists. (I suspect it does, but have no proof it does.)

 

Interesting about the tach needle. When I hooked up the Durametric this morning to get codes I did see the tack needle "bounce" about 3 times, then stayed as usual. I do not remember ever seeing that happen before. I'm wrapping my exhaust with titanium heat shielding today or tomorrow and adding another bottle of water wetter to the coolant to try and keep the engine a bit cooler, but I'm starting to think the symptoms are much like the crankshaft position sensor going out. I found most info on the Boxster forums. I will probably just get one from Pelican and try it out. I doubt the durametric would help diagnose this as it either runs great or not at all. Wonder how it can test in those conditions? It's like I have no spark or fuel when this happens. All dash lights come on, but the starter cranks the engine and everything else seems normal. I hope its not a PITA to get to that sensor. I have big hands and forearms that typically get riped up from trying to reach anything. better that than a giant whole in my wallet. haha. Thank you very much for the input. Rep points!

 

Darn Macster. I tried to add rep points, but I must have given you rep points sometime recently in some other post because it says I have to spread some rep points around first. haha I can't help it that you have good info???? lol... ordering the crank sensor now. Lots of Boxsters seem to have this exact type of symptom. I'll reply back when its all done, but how do I test her out without getting stranded? It won't heat up enough revving it in my driveway. I think I have one more AAA tow available. Hope I don't need it. Thanks again

 

Since you have the Durametric, why don't you just log it and keep it plugged in the whole time while you're driving?

 

Driving = Stranded. I don't know anyone who could follow me in a tow truck. Waiting 3 hours in 100 degree heat is no fun either. How can I drive and watch a computer screen? Illegal to even text here. For good reason. I'll post back after I get the CPS in and wrap my exhaust.

 

I'm guessing you don't know about the logging functionality in your Durametric.

http://www.durametric.com/porschedataloging.aspx

Here's the manual in case you need it: http://www.durametric.com/Durametric...ion_Manual.pdf

 

Something new this morning. I tried to start the car and nothing happened except my oil gauge flickering and my tach bouncing? I have never seen this? I then placed it in neutral and she starts right up. Put it back in park, turned it off, then she started as usual again? My ignition switch is only 3 months old. Old one was throwing a seat belt receptical error code and a dash light. Funny how the ignition switch was the fix for that. Got my pipes wrapped today and still waiting for the crank position sensor. Starting to wonder if my immobilizer is acting up? It did rain super hard last night. wonder if it is getting wet. I'll pull out the driver's seat tomorrow when I install the CPS. I have seen waterproof housings for the DME. Im thinking of using a light silicone sealant just in case. I'll know more when I take a look. Getting tired of Porsche. I'm selling my 99 Carrera after its all fine and selling my Cayenne Turbo too. Those are costing me too much for repairs. Seems never ending. Even my 996 Turbo busted the shift cable attachment. I never thought I'd say this, but I may be giving up on Porsche. Maybe just stick to the 911 Turbos. I love that car. The repair shops here charge ridiculous fees and trouble shooting is never easy. BTW...I do know how to log with the Durametric, but the hard part is finding all the normal values as Durametric will not tell me when I call. I don't have a service manual for all my Porsches. Just the 996 Turbo. What is the normal value on the Durametric for the CPS, and all other sensors and relays? That would be great info. Thanks...

 

There have been posts that describe checking the electrical signal from the crankshaft position sensor and by what the signal looked like confirming the sensor was operating properly or not.

If the sensor is failing when hot though unless one can do this when the sensor is hot and failing the odds are the sensor electrical signal will be just fine.

However, if one can use a Durametric to log engine metrics one might be able to capture when the CPS goes bad. One might have to deduce this by say the engine RPMS flatlining or ignition timing going away or short term fuel trims going off scale. Sorry, but I can only guess at what engine metrics might react and in what fashion when the CPS signal goes away.

A heavy rain with any electrical like symptoms after always gives me the hebejebes. I would advise you to not waste any time but check for any signs of moisture in the cabin under the passenger seat where the security module is located.

However, when the security module is involved the behavior is the engine does not crank at all. The security module must recognize the key's RFID and only then does it let the starter operate. When the starter then engages the flywheel and spins the engine whether the engine starts or not is not affected by the security module to the best of my knowledge.

I note you have a Tip. There have been issues with something inside the Tip shift linkage that can have the engine controller fail to recognize the Tip is in Park (or Neutral) and refuse to allow the engine to crank. However, I gather the engine cranks just fine it just doesn't start. This is not the behavior I would attribute to a problem with the Tip linkage. (In this regard it is like the clutch interlock switch in manual equipped cars. If this switch is bad or not working properly the engine just doesn't crank. While the dash lights up normally when the key is turned on when the key is turned further to engine start position there is just crickets.)

 

I replaced the crank position sensor and wrapped my exhaust. All is now fine. She is running great. Hope this can help someone with similar symptoms. It has been raining hard and that is not an issue. It was the CPS. Not too hard to replace. The clip was the most difficult thing to get to. I had to drop the engine a little. My ignition switch happened to go out as well after cranking and cranking I guess. It's replaced and everything is now fine. Whew! Thanks guys!