Hyundai Accent LC 1999 P1128
 

Hi all, i am new to the group and i am sick enthusiast for Hyundai. I own Hyundai Accent LC 1.3 62kw 1999. I bought the car new back in 1999 year direct from Hyundai dealer. Till today, i can't say any bad word for her. 20 years of revving and high speeds and all stuff and the engine still runs like charm like new. But i have one question. 2 years ago i added LPG system because here in my country the LPG is very cheap to buy. Gasoline is very very expensive.
Now the problem: When i drive on LPG the check engine light will flash with Error P1128 - Long Term Fuel Trim Multiplicative System Too Lean. If i drive on gasoline the problem will dissapear but as soon as switch back to LPG the problem will come back. How can i solve this because it's really annoying. I understand the electronics so feel free and write if there is any electronics solution to this problem.
And two more questions:
Does P1128 error reduces power and mileage or it's just information error ?
Does your Accent yurn oil ?
My Accent burns oil from the date it was bought till today and values are the same after 20 years. I try with Castrol, Valvoline, Motul, Aral but same result - In city driving burns 1 liter per 1000km and on highway sometimes burns very little oil, sometimes it will not burn any oil.

Thanks in advance to all people for answers !

The vehicle's computer needs to know when the system is running on gasoline or LPG. In the process of installing the added system has this been changed so the computer gets this info?

The lpg system is connected to ignition coils, fuel system, O2 sensors and but i don't think they remmaped the ecu or stuff like that because car is 1999 year and i don't think the ecu supports functions like that. But if it supoorts, can i make some changes ? Because in my country, 80% of the mechanics are without needed knowledge.

I would suggest that you read up on "Flex fuel vehicle operation" and that should help you to determine what has been left out.

Thanks man !