Please help, strange problem 944
 

Hi,
I have a strange problem developed lately with my 87 944. The engine speed would drop to the idle RPM, about 1000, and of course the car slows down if it is in gear, then if gas pedal is pressed down it accelerates to about 2000 RPM, and when drops again to 1000, in equal time intervals, approximately 1 sec to accelerate to 2000, and 1 sec back to 1000.
The car is jumping like a frog meanwhile.
The same thing is happening in neutral. Idle is OK, but if gas pedal is pressed, no matter how far, accelerates to 2000, drops to 1000, like a clockwork.
Any ideas where to start looking for the cause of this will be greatly appreciated.
Thank you,
Alex

Just a SWAG....(scientific wild ass guess) but I would check the throttle cam/body assembly and the air meter box. There are return springs and cables on the throttle body that could be jammed, broke or stuck.

The air meter box, between the air filter and the throttle body, has an electircal contact inside that controls the sweep of the butterfly valve in the meter.

After many years of interstate driving, mine developed a MAJOR stumble when you accelerated up thru the gears. The contact patch in the meter was being worn in just one place by keeping the throttle in one position for prolonged interstate driving.

When you tried to accelerate up thru the gears, the meter would move along the contact until it hit the worn part...then the motor would die...until it moved past the worn part, and then it would pick up and keep on accelerating. It would knock you out of the seat it was so hard.

I replaced the entire air meter box with a used one... good to go.

Good Luck
:)

When you let off the gas at high RPS does it pop and backfire?

Check out the TPS when this is happening or try unplugging it to see if the problem goes away. With the TPS unplugged, your idle will vary aroung quite a bit.

Rob

anything frozen?.. throttle wise?.. check cable cam spring.. does it occur after a warm up period?..

Thanks a lot...
Roger - no, it doesn't pop or backfire, just quetly drops to 1000.
FR Wilk- thanks for usefull links.
Frank- no, cable is OK, because I tried to move throttle cam manually, moves freely back and forth, and yes, it is happening after warm up
Looks like I will start with TPS...will try to post what I find
Alex