Tip & How-To about 1999 Volkswagen Beetle
I bought this car knowing it was a fixer-upper and needed a lot of work. Eventually I got most everything working and finally was able to drive it without the check engine light constantly lit.
However, one problem has eluded me to three years now, and I just finally solved it!
The symptoms were that while cruising at a constant speed, the gas pedal would suddenly start to move under my foot! It would accelerate and decelerate, usually only within a range of 3-5 mph, and if that was all it was I might have been able to ignore it. But every once in a while, it would basically stall out the engine; it would still be running, but pressing on the gas didn't do anything. While the pedal movement could start happening at pretty much any speed, it only ever died when I was on the freeway doing about 60 to 70 mph. I eventually got to the point where I could pop the car into neutral, turn the key off, restart the car and put it back in drive, all within about five seconds without stopping the car. Because restarting the car always put it back on track and stopped the pedal movement - no guarantee it wouldn't start up again, though, but since it didn't happen every time, that was what I did at the time.
I checked the scan codes with an OBD-II reader, and there were never any trouble codes or pending codes set, but I could see that there was freeze frame data available; unfortunately AutoXRay wanted a hefty sum to unlock that feature on my scanner, so I never was able to use it.
I've put two MAF sensors into the car, replaced all the oxygen sensors, the catalytic converter, pulled the throttle body and cleaned it, checked for vacuum leaks and could never find the problem. Research on the internet didn't help either, so I lived with the problem for three years.
However, I ran across a listing on RepairPal that talked about a similar problem, which turns out to have been caused by a broken vacuum hose to the pressure regulator
Posted by Jerry on
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