911 2

i have a previous topic whereby my 1987 3.2 has a habit of fluctuating revs looked at the idle control valve today and it has a arrow marked on it to show which way the valve should fit should theis arrow bw facing towards the air flow meter or facing down towards the floor
also when i mannually shut of the valve the revs stay low and then die what controls the idle control valve

Lorenfb

The arrow indicates the air flow direction, i.e. from the low vacuum side of the
throttle butterfly to the intake plenum side.

911 2

i think mine is the wrong way round then so if you are looking into the engine bay the arrow would be facing the top towards the engine lid

944ZEN

The Motronic (engine electronic) controls the ICV (Idle Control Valve). It measures the rpm and open or close it in small steps to control hov much air is bypassed to the engine, and thus controlling the idle speed.

The ICV can be paritially stuck (a little hard to open/close) due to sludge deposit and waer, so it jumps in larger steps than the Motronic expect, and thus making the idle irratic.

911 2

idle air control valve is fine i took it off and checked it with a 12v supply also cleaned it with carb cleaner and wd40 i think it may be the throttle position sensor and mixture
cant find the 3 pin plug which i am suppose to short to set the mixtures

Barry A. Waters

911 2 - This plug should be located under the plastic protective shield located just rearward of the ignition coil/fuel filter installation on the left side of the engine compartment. This shield also covers various fuses and relays that reside in the engine compartment.

According to Wayne Dempsey's 101 Projects book (well worth the money by the way) you need to jumper the "B" connector in the forward upper region of the plug (going clockwise) to the single "C" connection in the lower most region of the plug. This would serve to disable the idle volumetric control.

Hope this helps.

Barry

Lorenfb

"cant find the 3 pin plug which i am suppose to short to set the mixtures"

You don't use the 3 pin plug to set the mixture. Furthermore, you really don't
need to short that plug to set the desired idle, just unscrew the air bleed screw
a few turns. This works just fine to raise the idle.

Don't turn the mixture set screw without access the a CO gas analyzer. Remember,
this adjustment only affects the idle mixture. Again, make sure the ISV is inserted
properly.

911 2

thanks lads i was going to purchase the bentley mannual i have one relay on the left hand side with about three fuses and round plastic sections with around 4-5 holes in it there is no cover on this am i looking in the correct place will try and get a pic of it my idle is fluctuating and was told it could be mixtures therefore to test the mixture and set idle i would need to short the plugs b and c
have nt really had much luck first fuel tank leak then door strap breaks now the alloy has a slight leak i dont know if it can be welded and now the idle apart from that the car looks and drives very well

944ZEN

If you have a leak in the intake the Engine is sucking air that is not mesured by the Air Flow meter, and thus the Mootronic will calculate the engines running parameters incorrect, most likely to little gas is injected and mixture is weak. That could also disturb the idle.