idle revs up and down then stalls
Hey, my fellow volvo addicts, I hope you guys can help!
I drive a 1999 C70 2.4 L B5254T/56 turbo automatic
The summary: When starting the car, the idle revs back and forth between 1500 and 400 rpms (both the tachometer and the engine) and then stalls, unless I keep giving gas and accelerate to over 15 mph. No check engine lights on. For a few weeks prior, the rpm’s drop to 500 when shifting from drive or park to reverse.
Anybody has any idea what this could be? Vacuum leak, idle air control valve, EGR valve, throttle position sensor, MAF sensor, fuel injectors/pressure regulator/pump/damper, spark plugs? Please help!
The story: On the interstate, I got stuck in traffic for a bit - all the way to a halt. Then, when I got out, I hit the accelerator - to my knowledge not too hard, but still to have a bit of a kick - and it seemed like something gave in, because it just suddenly stopped accelerating. Out of shock , I’ve immediately let go of the gas pedal and took it nice and easy to get her home, which was maybe 2 miles away. I even stopped for a while at an intersection, accelerated, and slowed down a few times, but taking it slow, I made it home fine.
Then, curious as I was of what the hell just happened, I jumped back in my car to see if it would happen again. The car started fine in park, a bit of hesitation, but then, when I went in reverse, it started "bucking" - revving up to 1500 to 2000 rpms and down to about 400, back and forth, like crazy! It stalled on me several times. When I picked up a little speed - say maybe 15 mph – the “bucking” stopped. Slowed down - started again.
I have to say that I kind of saw it coming, because when you´ve driven a car for a long time you can just sense something is not right. She´s been acting out for a few weeks with a bit of a stuttering and, going from drive or park to reverse, the rpm´s would really drop to around 500 rpm´s with almost the feeling that she would quit on me.
Thank you, guys.