quick question about switching from gas to petrol

[JD]

ok this has happened a couple of times.
when i swich from gas to petrol and drive after it swiches fully and i wait about a minute and then drive it will lack power, use more fuel ( does for about 15mins ) and the check engine light will come on for about 30secs.

but if i wait about 3 mins before driving off it will run fine and no engine light.

and it doesn't do it at all when i swich from petrol to gas even if i drive immeditley after swiching.

not too phased really just wondering why it does it on petrol and not on gas

[mouce]

Check and see what error code the warning light responds to. See what is playing up. There's enough threads on here about how to read the codes, post it (them) up and we'll tell you what it means.

[Cheap6]

One explanation is that the ECM is learning the fuel mixtures on LPG, resetting the block learn values, and then running badly when operating in open loop ie. O2 sensor cold, open loop idle, using those values until it can operate in closed loop and relearn the appropriate values on petrol.

[JD]

One explanation is that the ECM is learning the fuel mixtures on LPG, resetting the block learn values, and then running badly when operating in open loop ie. O2 sensor cold, open loop idle, using those values until it can operate in closed loop and relearn the appropriate values on petrol.

well thats what i was kinda thinking but it doesn't explain why it does it only swiching back to petrol. and not switching from petrol to gas.

might just let it idle and adjust al the time.

[FXST01]

I got a feeling its running on both gas and petrol until all the gas has been expended from the gas line. Does the gas get fed through the throttle body and not the injectors, if so then maybe vacuum is helping it to draw off the gas.

When switching to gas from petrol, its immediately cutting the petrol off at the injectors.

My 2c

[Cheap6]

well thats what i was kinda thinking but it doesn't explain why it does it only swiching back to petrol. and not switching from petrol to gas

It would because the ECM is not controlling the fuel on gas but FXST01 your suggestion sounds reasonable.

[JD]

I got a feeling its running on both gas and petrol until all the gas has been expended from the gas line. Does the gas get fed through the throttle body and not the injectors, if so then maybe vacuum is helping it to draw off the gas.

When switching to gas from petrol, its immediately cutting the petrol off at the injectors.

My 2c

i'd agree with that, im getting the throttle body cleaned on the weekend so hopefully it will switch over a bit better.

[adams vn]

i had the same problem and took it to a auto gas place and got it tuned for 30 bucks, although it still did it it wasnt as bad and i was told the explanation for it was there is still gas in the lines.

[JD]

i had the same problem and took it to a auto gas place and got it tuned for 30 bucks, although it still did it it wasnt as bad and i was told the explanation for it was there is still gas in the lines.

its not going to stuff anything up, still having gas in the lines is it?