1989 C4 Non starter
 

Hi all.

First question of my subscription so please be kind if the answer is blindingly obvious.

I haven't used my 1989 C4 much this year but last weeks weather prompted an outing but when I went to fire her up she just turned over. However, when I opened the engine lid and then tried it started. I also noticed a ticking noise that seems to be coming from the vacuum valve fixed on the throttle body.

Is it likely to be the vacuum itself or an associated item? Is there any way of telling without buying a repalcement valve and trying it then?

Thanks for your help

AJ

Hi AJ - welcome to Pelican.

I'm not sure what you mean by Vacuum Valve on the throttle body. Are you referring to the ISV - Idle Stabilization Valve? Could you snap a picture?

Hi Don.

This item appears on top of the throttle body (I think). What I cannot understand is why the engine would not start with the engine cover bonnet closed but would start with it open??!!

AJ

Looks like p/n 911 618 123 01 - Vacuum Valve.

Just guessing here - ticking noise might be a failing solenoid in the valve. If you disconnect the wires, I imagine the ticking stops?

As to why the car won't start with the bonnet down, look and see if the hinges are moving anything. Could also be an intermittent ground connection that moves when the lid opens?

Just guessing...

Looks like p/n 911 618 123 01 - Vacuum Valve.

Just guessing here - ticking noise might be a failing solenoid in the valve. If you disconnect the wires, I imagine the ticking stops?

As to why the car won't start with the bonnet down, look and see if the hinges are moving anything. Could also be an intermittent ground connection that moves when the lid opens?

Just guessing...

Thanks Don. Will give it a try. What is the function of the vacuum valve and am I right to call it a vacuum valve assuming I need a new one.

Aj

If that is like my turbo, that looks like the solenoid valve for the smog equipment. I removed mine and capped off the throttle body connection.

It shouldn't make any difference in your ability to start the car.

RT

I could have been coincidence that the car fired up when you opened the lid. Does it die when you close the lid with the engine running? If not maybe it was the DME relay on its way out or just fuel pressure building up in the system preventing it from starting right away.

The valve in your picture is driving the actuator for the resonance flap in the intake plenum. It should not make any ticking sound. It switches the pate at around 5000 RPM to change the intake runner configuration. Once you switch the ignition to ON you will hear it once switching as long as there is sufficient vaccum stored in the cannister. Are you saying it makes a constant ticking noise? And did the ticking stop when you disconnected it?

There is another black valve close by which is used for the tank venting function. And then there is the idlle control valve. It is a silver can half the size of a soda can that lets air into the engine. It's operating frequency is somewhere around 80Hz and barely audible especially when the engine runs.

Cheers,
Ingo

I'm having the same exact issue with my resonance solenoid, the is a loud ticking when key is on 2 position. car cranks but won't start. When I unplug the solenoid then the carbon canister vacum switch right below starts ticking. Then I unplug both ticking stops. I replaced both parts are the ticking continues. Please help.