Volvo 1988 740 GLE Non-Turbo: High RPM @ start and dieing.

Hello all,

The car has 165XXX miles on it.

The car would start in a very high idle rpm 1500 - 2000 RPM or a
little lower and when put in gear [Reverse or Drive] it tries to die
but sometimes doesn't but most of the time just dies. Till now, it
starts again right away. When it does start though if I try to push
gas a bit to make hold it, it sort of just doesn't respond as you
expect in a moment or two it just goes as if nothing was wrong at all.

In the times that it starts with no problem, it just starts with no
problems whatsoever.

Another probably related symptom probably, when it is in the Parked
Gear, it exhibits a high idle RPM [1500-2000] but when in Drive gear
standing in a light it is around 1000 RPM. Are these numbers normal.

 

I'm thinking you will find the problem within a few inches of the throttle
plate. First, check the hoses on the Idle Air Control valve (under the
throttle body) for cracks. They are probably hard as wood now, and a crack
in the hose on the intake manifold side will cause your symptoms. If that is
okay, carefully open the throttle a tiny bit while listening closely (engine
off). You should hear a faint click from the throttle position switch each
time you move the throttle the tiniest bit off idle and another one when it
goes all the way to idle. Finally, check all the hoses from the intake
manifold for big leaks.

Normal idle speed is somewhere around 700 rpm, in gear or out of gear. It is
set by the computer using that IAC valve under the throttle body.

Mike