940 Turbo randomly stalls and wont turn on

[Laird Scooby]

Is it engine speed related or road speed related or none of the above?

I'm thinking it could be something like propshaft centre bearing, wheel bearing, worn drop links, shock absorbers, loose heatshield on the exhaust or something different that needs invesstigation in its own right.

[ThermalShark]

Seems like its engine speed related. Priority is to get the car working though.
I'm going on a short vacation so I can't work on it but I've got a time for a mechanic when I come back, maybe they can find things better than I with my limited experience.

[ThermalShark]

Something came to mind when I was thinking about what could be wrong. Before I bought the car it had been sitting still for a whole year in a garage, is there something that would fail if the car sits for that long?

[Laird Scooby]

The fuel would go stale and there's a high chance of condensation in the tank, especially as the ethanol content of the fuel has water in.

Try the methylated spirits to eliminate the condensation in the tank.

Other than that, the brake fluid should really be renewed for similar reasons, all rubber components checked/replaced (including the cam belt) as necessary, distributor cap cleaned inside and out (particularly the contacts), engine oil/filter change, possibly a coolant flush and change - i'm sure there's a few things i've missed but basically treat it as recommissioning after a long lay up.

[aardvarkash10]

Originally Posted by ThermalShark

Something came to mind when I was thinking about what could be wrong. Before I bought the car it had been sitting still for a whole year in a garage, is there something that would fail if the car sits for that long?

Cars are mechanical devices, mechanical devices don't like sitting still. Dave's on-point with the fuel and brake fluid - both are suseptible to water contamination over time. Water also condenses in the oil pan and contaminates the engine oil.

If I had a car that had sat that long without being regularly run up to operating temperature, I'd be inclined to replace ALL fluids and filters as a mater of course.

[TonyS9]

Couple of suggestions

CPS+ingition amp problems will be apparent with the tacho needle not moving. This is a good diagnostic tool. If the needle moves a little while its trying to start but not starting, its not the CPS or ignition amp.

Air leaks - I've had rought running recently and it was caused by the inlet gasket being cracked/broken at one end. I hadn't tightened up the manifold nuts evenly and it was a bit skewed leaving one end of the gasket not well clamped.
A worse air leak will cause stalling.

Stalling after acceleration - This is the dump valve in the turbo not actuating leaving the manifold pressurised at idle, causing too meak a mixture.

[ThermalShark]

Back from VROM to try figure this out.

I changed the oil and filter when I first got the car, but have not touched the brake fluids. The car has ran through 5 tanks of gas just fine after purchase, is there any way to test if there is water in the tank without draining the whole thing?

The dump valve should be working fine as I can hear it when lifting off throttle.
What is a good way to test for air leaks?

[Laird Scooby]

Originally Posted by ThermalShark

is there any way to test if there is water in the tank without draining the whole thing?

You could add some methylated spirits on the grounds it probably has got water in the tank, it won't harm it either way and will get rid of any condensation.

There are other ways to find out but all need some level of dismantling.

[ThermalShark]

Alright I'll try find some and add it. How much should I add? I have around half a tank.

[Laird Scooby]

About a litre, maybe a bit more as there's a fair bit of petrol in there. It's better to add it when there's less petrol, down to about 1/4 of a tank is usually the most petrol in the tank so you get a higher concentration of meths - it's more effective at clearing the condensation that way.