Dears,

Can someone told me what was expected values for long and short fuel trims. Car has BRC CNG installed and measuers for SFT +90 and LFT 0 on CNG ECU when driving on fuel. There is no any error.

Hi. Sorry I can't answer your question but can I ask what you are using to measure them? I've been trying to figure out if it can be done with MES but so far haven't been able to.

Hello, i’m was attached image with reading of short and fast fuel trim on idle so i need to verify is it ok.

Sorry I haven't been back to you but we have a sick child in the family just now which is involving us all in supporting Mum and Dad and generally trying to be helpful.

I know nothing about compressed natural gas diagnostics but if you are taking those readings when the car is running on gasoline the figures look crazy? Here's a wee video which gives the basics on what to expect by way of fuel trim readings:



With a reading as far out as your STFT is you must surely have some, or at least one, DTC posted? If so this might point you in the direction of the problem?

Do please let us know how you get on with it. I'm very interested in all this sort of stuff but lack the experience to make sense of it. I'm slowly getting up the curve though.

regards
Jock

PS Can I ask again what you are using to obtain these results/graph?

Hello, thanks for info. First i hope so that your child gonna be better soon.
I’m was used some diagnostic from ali express, but other professional fiagnostic shoed me same results. Readings was from petrol. I was read and wached youtube videos about fast furl trim and short fuel trim but i dont know what ahould i expect when i read from engine with 2 valuve and 0.9 twin turbo.
There is no any dtc error.