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1999 996 engine stalls at highway speed after driving 1-2 hrs, restart

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I have a perplexing problem, my 99' carrera engine stalls after driving 1-2-3 hrs, downshift drop lower gear dump clutch keeps going, even at freeway speeds. This weekend happened, able to pedal like that for 80 miles. I noticed the car is running between 190-200 temp. Recently changed crank sensor, thinking a possible solution. After install drove vehicle flawlesly for 3 hours in 100 plus outside temp, car at about 200 on temp gauge. Now after not driving for about 3 months as I described above it happened again. No codes appear and check engine light not on. Have any ideas, camshaft sensor, fuel pressure regulator, ecm, etc.?

Edited by jimb6850
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Has the fuel filter been replaced? Checked and cleaned the idle stabilizer? Both radiator fans running on both low and high speed?

Does the car die when idling and just driving around town? Or the stall or cut out happens even when at speed?

Any work done on the flywheel?

When you said no codes, did you use Durametric or just a generic OBDII scanner?

Edited by Ahsai
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Ever cleaned the radiators? 200 is high temp at speed, there should be plenty of airflow to keep at indicated 180 temp when running at highway speeds.

As Ahsai indicates, lean fuel mix could cause higher engine temp under load and cause stalling.


Edited by fpb111
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  • 8 months later...

I have the same problem. Drove 200 miles to Taos last summer with engine running for 20 seconds stalling for 6 seconds then restarting long afternoon that was stalling out 2-3 times per minute. Nightmare. Guys in Denver had it for 5 weeks took apart front to back, looked at all electrical connectors and found NoTHING.

Feels more like electric than fuel. When it quits stalling (6-7 seconds cut out each time and very consistent) stay in the gas and it bumps hard into acceleration again - like electric spark back on more than fuel restored as a guess).

I have a k-N air filter which I wonder if it isn't oiling up the MAF and causing the computer to think it should quit running for a little bit. Will clean MAF and go back to paper this summer as a test.

Only happens on warm days after 1-2-3 hrs of driving. I've also noticed the last couple of times that warmer engine temps preceded the issue. Thinking about a low temp thermostat as a work-a-round.

Super frustrating to have such a great car that just can't be used for a road trip, any tips or clues leading to solution will be REWARDED!!!!!

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Saw you posted at Pelican as well. Somebody recommended a Durometric. Did you get any satisfaction since July?

fuel or electric? Can't believe a diagnostic tool would help cause I had mine with the pros for five weeks, sure they would have run a diagnostic.

Pulling mine out of storage and would like to get this DEAL breaking issue resolved-

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