Strange Stag Issue

[JamesV6CDX]

On idling only, occasionally the gas light flashes slowly and it goes back to petrol.

Before doing this, the engine "falters" or misses a beat. Never does it at cruising speeeds.

No fault codes in Gas ECU or Engine ECU!

I'll have a proper look tomorrow, but anyone care to hedge their bets?

[TheBoy]

Switchback RPM too high

[JamesV6CDX]

Switchback RPM too high

Nothing has changed in the config though - and it's only just started doing it? 

It's as if it errors - Eg, won't let you switch back to gas until the engine has been turned off. I thought that would at least log an error in the gas ECU?

[Lazydocker]

Magic injectors?

[Kevin Wood]

The gas ECU is seeing something it doesn't like, be it low RPM (what is the "switch back to petrol" RPM?) or low vapouriser temperature, low vapour pressure, missing injector circuit, etc.

Are there any errors logged in the stag ECU? If not, look at the live parameters while it's idling and see if anything is getting close to the switching threshold.

Mine is currently doing this due to a loose connection on the vapouriser temperature sensor (must fix that ).

[tigers_gonads]

Check your alternator voltage James 

Mines on its last legs (13.5 volts max) and will throw up a low voltage warning / switch back to petrol at idle sometimes 

[Kevin Wood]

Check your alternator voltage James 

Mines on its last legs (13.5 volts max) and will throw up a low voltage warning / switch back to petrol at idle sometimes 

Yep, good point. Alternator output will tend to pick up at higher revs, hence problem at idle only.

[Lazydocker]

The gas ECU is seeing something it doesn't like, be it low RPM (what is the "switch back to petrol" RPM?) or low vapouriser temperature, low vapour pressure, missing injector circuit, etc.

Are there any errors logged in the stag ECU? If not, look at the live parameters while it's idling and see if anything is getting close to the switching threshold.

Mine is currently doing this due to a loose connection on the vapouriser temperature sensor (must fix that ).

He says no errors in either ECU

I asked about Magic Injectors (I'm sure that's what he's fitted) because this is a symptom I have heard of with them

[Kevin Wood]

The gas ECU is seeing something it doesn't like, be it low RPM (what is the "switch back to petrol" RPM?) or low vapouriser temperature, low vapour pressure, missing injector circuit, etc.

Are there any errors logged in the stag ECU? If not, look at the live parameters while it's idling and see if anything is getting close to the switching threshold.

Mine is currently doing this due to a loose connection on the vapouriser temperature sensor (must fix that ).

He says no errors in either ECU

I asked about Magic Injectors (I'm sure that's what he's fitted) because this is a symptom I have heard of with them

Ahh, didn't spot that.

How would the injector make it switch back to petrol, though? ECU has to have made that decision (perhaps due to the injector malfunctioning in some way) but I'd expect a code in the LPG ECU. My money is on one of the parameters going outside the LPG running range (perhaps due to a poor connection as I have).

[Lazydocker]

The gas ECU is seeing something it doesn't like, be it low RPM (what is the "switch back to petrol" RPM?) or low vapouriser temperature, low vapour pressure, missing injector circuit, etc.

Are there any errors logged in the stag ECU? If not, look at the live parameters while it's idling and see if anything is getting close to the switching threshold.

Mine is currently doing this due to a loose connection on the vapouriser temperature sensor (must fix that ).

He says no errors in either ECU

I asked about Magic Injectors (I'm sure that's what he's fitted) because this is a symptom I have heard of with them

Ahh, didn't spot that.

How would the injector make it switch back to petrol, though? ECU has to have made that decision (perhaps due to the injector malfunctioning in some way) but I'd expect a code in the LPG ECU. My money is on one of the parameters going outside the LPG running range (perhaps due to a poor connection as I have).

The more I think about it, I think you're more likely to be right. Especially as it isn't logging a fault, which I pointed out to you

Apparently the Magic Injectors can wear quite quickly and the first symptom is idling faults Although there were also comments that there have been some poor quality batches of them recently

[TheBoy]

Slow flash means a required parameter has not been met. Fast flash is error.

So, IMHO, its a required parameter is misconfigured, or a sensor fault.  In my simple mind, anyway. So I'm with that Wood fella.

[Lazydocker]

Slow flash means a required parameter has not been met. Fast flash is error.

So, IMHO, its a required parameter is misconfigured, or a sensor fault.  In my simple mind, anyway. So I'm with that Wood fella.

Yep... I'm with him to (as per my above post ) and my money's on the temp sensor too

[Gaffers]

I'd say sticky ICV and RPM switchback too high

[Lazydocker]

I'd say sticky ICV and RPM switchback too high

Really? On a 3.2?

It's got to be a switching parameter though

[tigers_gonads]

Slow flash means a required parameter has not been met. Fast flash is error.

So, IMHO, its a required parameter is misconfigured, or a sensor fault.  In my simple mind, anyway. So I'm with that Wood fella.

Arh, i'll have to read the stag manual one day