My Car Stalls When It's Hot (Around 205 Deg. F)

[vtf430]

Hopefully someone had this same issue before. I have a '99 996 cabriolet. It has been running absolutely fine for the past 5 years. Never even had any problem. Did a 60k service 6 months ago (spark plugs, oil & transmission oil change, etc.) 2 weeks ago, I drove around for about 20 mins & parked. The car wouldn't start (cranks just fine but seems like not getting fuel) I waited for about 5 minutes & it starts again. Last week, while at a stop lights the car stalled. I notice the engine temp. is around 200F+. Now, if I let the car runs until temp. is over 200F, it would stall again

Anyone has any idea? Thank you in advance...

****I wanted to edit this so that the next person with the same problem doesn't have to read the whole thread to find out the solution. If you have the same issue, 99.9% sure it's the CRANKSHAFT POSITION SENSOR!! Good luck!

Edited July 15, 2010 by vtf430

[juniinc]

Any code?

check the fuel pressure regulator,,,

[vtf430]

Any code?

check the fuel pressure regulator,,,

No code at all. I'll check the regulator to see. Thanks

[wvicary]

Could be a failing relay or a engine speed sensor. With your code reader can you measure engine RPM while cranking?

[911mike99]

Any code?

check the fuel pressure regulator,,,

+1, Or could be the fuel pump. I had a VW that did that and it turned out to be fuel pump.

[vtf430]

...Let the car ran until it reaches around 96 deg. C, it stalled as usual. Replaced fuel pump relay, but it wouldn't restart. It seems like the engine has a cutoff point (coincidently) around 96 deg. C. It wouldn't restart usually around a few hours later. It feels like something really simple, yet I'm pulling my hair out. I'll try to get some info on how to check the fuel pressure to see whether the fuel pump is bad. I might be way out there but anyone thinks it's a thermostat issue?? It looks like the engine overheats & turns itself off everytime around the 96 deg Celcius.

Thanks for the suggestions as always...

[vtf430]

...Well, after reading info on other ppl that had similar issue, I replaced my fuel pump. Unfortunately, it didn't solve the problem.

I'm narrowing down to maybe the cooling fan switch or some sensor that triggers the cooling fans to come on. I've noticed that the cooling fans don't always come on when temp is over 190F. Also, the fans only come on for about 30 seconds max. I'm not sure if that's normal.

Here are the 3 things I'm looking at: Fan switch, thermostat, water pump. What do you think? Please chime in if you had a similar problem before. Still searching for answer....

Thanks a million..

[pcvinsel]

You might want to look at the Idle Control valve. I was having a stall problem and the problem was that the ICV was pretty dirty. I was able to disassemble it and completely clean it and now the idle is smooth again. My problem was stalling in all cases but I can definitely see that your could have a dirty control valve that is especially sensitive to higher temps.

Peter

[vtf430]

Thank you Peter. I'll give it a try. It wouldn't hurt. After that, I'll have to give in and take it in to a shop :(

[1schoir]

Thank you Peter. I'll give it a try. It wouldn't hurt. After that, I'll have to give in and take it in to a shop :(

VTF:

Don't take it into a shop!

I think Peter is onto something...

Take a look at the following thread...It's almost the exact problem with a '99 Boxster that has a '99 3.4L engine from a 996:http://www.renntech....__1#entry159987

Regards, Maurice.

Edited June 18, 2010 by 1schoir

[vtf430]

I'm sure nobody wants to take it to the shop if they can help it. In my case, I'm afraid I might be spending more $$ going in circle than taking it to the shop. The crazy thing about it is, the car still runs perfectly normal. No sound, no glitch, no code, no smoke, anything!! When it get to about 200 F, it will shut down instantly. I wouldn't be able to restart until about an hour later.

Sorry for going around & around explaining my situation :)

Please HELP!

--vincent

[wvicary]

Idle speed motor will cause an Idle fault not a no start condition. I would have the engine speed sensors tested when the stall occurs.

[1schoir]

I'm sure nobody wants to take it to the shop if they can help it. In my case, I'm afraid I might be spending more $ going in circle than taking it to the shop. The crazy thing about it is, the car still runs perfectly normal. No sound, no glitch, no code, no smoke, anything!! When it get to about 200 F, it will shut down instantly. I wouldn't be able to restart until about an hour later.

Sorry for going around & around explaining my situation :)

Please HELP!

--vincent

Vincent:

I hear you!

Read that thread to which I posted the link above. It really does sound like a distinct possibility because Stefan had very similar symptoms.

Regards, Maurice.

[vtf430]

Wvicary:

do you know what controls the no start condition? After it stalls, I tried to unlug the battery for 10min to reset. It still wouldn't let me start the car! Also, what would the engine speed sensor tell me? I hope I ask the right question.

Best regards,

--vincent

[vtf430]

Maurice: thanks for the suggestion. I've read that thread a few times, & I don't think I have the same issue. Mine pretty much runs normal until it gets to 200f & stalls out, consistently every time.

Btw, it seems like an overheating problem that I'm having but no warning light at all before it stalls out. I've actually seen my temp gauge up that high before many time.

More research...

Thanks again.

[SPIRO]

Consider a faulty crakshaft position sensor. If these overheat, they can fail, not allowing the car to start, but temporarily come "back to life" after the engine cools down a bit.

[wvicary]

The speed sensors can go open circuit when hot or if the internal magnet is damaged the heat can cause it to expand which results in a weak AC signal which the DME can't use to pulse the injectors or ignition systems.

I should note that cold solder connections in relays/modules can also cause a no start condition but you need to rule out the speed sensors. I hope this makes sense and is of some help.

[vtf430]

Once again, I really appreciate all the replies. The info is defintely valuable! After reading non-stop in the last few days, now I'm thinking my car is NOT really overheating. I'm narrowing down to "some" sensor such as crankshaft position sensor, engine speed sensor, fuel injection pressure sensor causes the NO START condition. My questions now are:

1) why would a broken relay, module or a sensor be okay again after the car cools down again?

2) would a bad sensor trigger a fault code?

3) right after the car stalls, can I take out certain sensor & test it?

4) Is it true that if the Fuel injection pressure sensor fails, I should see fuel when I pull of the vacuum hose that attaches to the sensor?

I think I'm getting somewhere! Hopefully :P

best regards,

--vincent

[ravengolfer]

Once again, I really appreciate all the replies. The info is defintely valuable! After reading non-stop in the last few days, now I'm thinking my car is NOT really overheating. I'm narrowing down to "some" sensor such as crankshaft position sensor, engine speed sensor, fuel injection pressure sensor causes the NO START condition. My questions now are:

1) why would a broken relay, module or a sensor be okay again after the car cools down again?

2) would a bad sensor trigger a fault code?

3) right after the car stalls, can I take out certain sensor & test it?

4) Is it true that if the Fuel injection pressure sensor fails, I should see fuel when I pull of the vacuum hose that attaches to the sensor?

I think I'm getting somewhere! Hopefully :P

best regards,

--vincent

I am having the same issue with my 2000 Boxster, it reachs 184 F and dies and will not restart until it cools down below 160 F. I've order a pulse sender aka crankshaft position sensor and fuel pump, but 90% sure it is the pulse sender. I am looking for a fuel pressure gauge for a Porsche and can not seem to find one in Tucson or at Snapon.com. Would anyone know where to find this tool?

Thanks

Michial

[vtf430]

Michial, please update your progress if you get it fixed before me. I've given up & took it in. It has been in the shop for 2 days, & they haven't figured it out either...

[ravengolfer]

Michial, please update your progress if you get it fixed before me. I've given up & took it in. It has been in the shop for 2 days, & they haven't figured it out either...

Vincent,

I am a EE and make a living from troubleshooting and solving difficult problems and this one should be easy. I've ordered more tools to aid in troubleshooting, but still looking for a good fuel pressure gauge. I would like to find a pressure kit that will also work on my Mercedes, BMW and Lexus. They all have the Bosch system.

Did you or your shop try the Pulse Sender? I will let you know as soon as I solve this one and please do the same.

Thanks

-Michial

[ravengolfer]

Vincent,

I just got her running and it was the Pulse Sender (aka Crankshaft Position Sensor) and it is called a "Impulse sender" at Pelican Parts. Odd I had no faults on the Durametric?

Item Name Item Price Quantity Item Total

--------- ---------- -------- ----------

986-606-112-02-M14 $131.75 1 $131.75

Impulse Sender, Boxster 986 (1997-2004), Brand: Bosch

-m

[vtf430]

M, I'm glad you got yours fixed! I just talked to my shop this morning, & they still haven't found anything. I did suggest the crankshaft position sensor, but they rejected that idea immediately! We'll see...

Thanks for the update.

[ravengolfer]

Vincent,

I think you have issue. It takes a 5 mm hex head and maybe an hour to change it, including taking the right tire off.

-m

[wvicary]

PMG fail often, the problem is most techs don't know how to correctly test the sensor. As for not setting a code, the reason is the parameters just were not met. If the sensor doesn't go open circuit the DME will often see no fault but if the sensor has low output it won't be enough of a signal for the DME to use and result in a no start condition.