Forester cutting out - help!

[cello297]

My Forester Turbo S has developed the habit of cutting out at about the time the thermostat opens. It is converted to run on LPG, but does this when switched to petrol or on the changeover when running on gas. When it cuts out it takes a minute or more churning before firing up again and then runs fine.

(It was previously missing, but this was finally sorted out with a replacement crankshaft sensor and new plug leads - the previous ones, which were brand new, were arking out.)

Can anyone come up with a solution before I finally lose patience and sell the car... oh yes and before my wife hits me over the head, because it is really my fault!

I'm all ears folks.
Shane

[stevieturbo]

How do you know when the thermostat opens ?

Its a bit of a vague description really.

[cello297]

I'm going from the facts that (1) the temperature starts to rise at about the same time - not a precise measurement - and that, if it is switched to run on gas, it would be changing from petrol at about the same time - also temperature specific.
These are not exact, but a good indicator, as it is always (bar once) at the same stage.
Any help would be appreciated.
Shane

[stevieturbo]

cello297 said:

I'm going from the facts that (1) the temperature starts to rise at about the same time - not a precise measurement - and that, if it is switched to run on gas, it would be changing from petrol at about the same time - also temperature specific.
These are not exact, but a good indicator, as it is always (bar once) at the same stage.
Any help would be appreciated.
Shane

Stat will not open until approx 80-90degC

Gauge will start to function around 40deg

It may be somehow temperature related, but it is not the thermostat.

So does it do the exact same problem on gas and petrol, or one or the other ?

Edit. Just re-read that it happens when switching from gas-petrol or vica versa. I would say the problem lies with the LPG system, and not with the actual car itself.
If it starts and runs fine at all times with petrol, then the car itself is fine.
Likewise once warm, I assume it starts and runs fine at all times ?

If so, the problem is with however the system performs the changeover.

Edited by stevieturbo on Tuesday 15th June 23:15

[syncro.]

Could be an issue with the lambda sensor heater. If the engine is trying to enter closed loop fuelling and the heater is broken the sensor will be too cold to accurately detect oxygen in the exhaust gasses and will not switch/take a long time to switch leading to the engine management excessively increasing or reducing AFR causing it to cut out.

When the engine is fully warmed up the sensor will be warm enough without the heater and therefore work correctly. Although bear in mind this is the best I could guesstimate from limited information.

Does the EMS run closed loop fuelling in lpg mode?

[cello297]

Guys, I'm most grateful for your help. The situation here is that I started this thread too late. There is serious stress in house, following problems that have gone on for too long. I went out and ordered a new car today and now have a happy wife at least. Many thanks. I doubt I will have my head under the bonnet of the new one for some time to come, so it's back to the TVR and serious troubles...
Thank you, Shane