Rough Running - (Cont)

[mercman1969]

Am slowly building up a picture of the rough running of my W163

It is dual fuel petrol/lpg

Car starts on petrol until ambiant temp ir reached and then it switches automatically to lpg

On start up the car idles but when revved or driven it coughs and splutters and the throttle is unresponsive. If you floor the throttle eventually it will rev but under normal conditions it is dog rough

Once the car is on lpg it runs as smooth as silk.....switch back manually to lpg and it is rough again

As the lpg side has its own ecu my fear is that the main ecu is playing up

My initial thoughts that it was ignition surely cannot be true as it runs fine on lpg?

Your thoughts / comments are appreciated

 

[mercman1969]

Anybody any comments on this?

I still hope it could be something simple but feel it is pointing at main ECU??

Anybody with a STAR system close to Grantham that could interigate it for me?

 

[Sp!ke]

I have to say that it seems to be a very rare thing for any merc to run right on lpg. I dont believe mercedes use of vacuum lines lends itself well to the conversions. Can you not take it back to the LPG installed for diagnosis?

BTW, your post is confusing, you seem to be saying it runs fine on lpg and then you say it runs rough on lpg.

You think a star diagnosis will help an awful lot with your setup?

 

[mercman1969]

NOPE,

dont think I have contradicted myself

The lpg WAS cutting out and did have a problem with pressure....when a pressure diff is felt in the lpg system it reverts back to petrol

It is running rough on petrol and that what leads me to think it is main ecu

if it were coils & leads it would run rough on lpg also which it isnt

the problem is definatly at the petrol end of things

 

[BlackC55]

maybe its a fuel pressure (petrol) issue?

 

[Dieselman]

Does the LPG system use the MAF, if not suspect that.

 

[mercman1969]

Does the LPG system use the MAF, if not suspect that.

MAF has been checked out and is running 12 Kg/min which is a good rating

usual readings is anywhere between 9 - 11 is considered good

 

[mercman1969]

Anybody with a STAR to interigate my motor near me at all?