The strange symptom - B230F - V740

I've got strange symptom in my car. I don't know, it's normal or not.
When I push the break pedal meny times (it's look like if I pumped by the
breaks pedal),when car is stopped, I've observed that the free turns go from
700 RPM to 1500 RPM,...If I don't push the break pedal the free turns are
700 RPM, but only I push this pedal many tims in the moment, the free tuns
go to the 1500 RPM.

Is it normal or not? I thnik maybe the breaks-servo id broke....


all the best....

 

I think the idle adjustment is too high, so the added amount of air the
brake servo adds when you cycle it rapidly is beyond the range of the Idle
Air Control valve to compensate for.

I recommend you check the vacuum hoses for leaks. If a leak is small enough
the idle control can hide it under normal conditions. If not a vacuum leak,
your idle probably needs adjustment.

The gurus can post the real way to adjust the idle, but I bet if you screw
the knurled black thumbwheel at the bottom of the throttle body in about one
turn the symptom will either disappear or be reduced. Do keep track of where
it was set originally in case the new setting causes stalling.

Mike

 

Could just be the non-return valve at the servo end or it's rubber seal.
Worth checking this simple thing first before condemning the servo.

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).

 

How can I check this??

 

If I good remember, I haven't Idle Air Control, because I've got LH 2.2
system,..and I set the free turn manual by knob.

 

I've observed the second symptoms,..whet I take the hall sensor for the hand
and I've moved them, the hall sensor isn't stiff,but I can move it for all
sides. It's normal or something is broken??