Lumpy running on petrol after switching from gas

[nickw]

If I drive the car (Saab 9-5 2.3 Lpt) on gas and I switch to petrol during the journey it goes lumpy and the engine check light comes on.
Also having driven on gas to work and the car has cooled down enough say by lunch time, it starts on petrol and is lumpy until it switches over to gas. But if the car is left overnight and I start it in the morning it's fine. Injectors were cleaned at the last service, plugs, fuel pump fine. Any thoughts would be appreciated. Cheers, Nick.

[mak-uk]

To me, that sounds like a tuning and/or fuel trim problem. Best get it checked by your installer.

[nickw]

Thanks Mak, will do.
All the best,
Nick.

[daveylitz]

what codes are logged?