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[Gintonic]

Good evening everyone
It's been a long time since my last post here I hope all are safe and in good health.
I have an Omega V6 3.0 manual from 2000. Since I m not in UK it's Opel omega executive (I think elite is the model in UK)
I have it for almost 2 years it runs on LPG
Since for almost a year it ran a bit rough, not as smooth as it should, ran like it had a missfire, all 6 cilinders were here but it was shaking a lot. Consumption on board comp was between 18 and 21 liter on 100 km. Comp diagnostics showed nothing.
2 weeks ago I took el. contact spray and carefully sprayed  all connectors that I could find in the engine area. Literally everywhere where the connector was I disconnected it and  cleaned it.
Engine started to run very smooth. Almost normal. I could place a glass of beer on engine. Vibrations are minimal but there are some mount s that I have to change that are the cause of very small vibrations
Main thing. Board started showing consumption of 13 to 16 liter per 100 km. So that's 5 liters less. Also in real life numbers are here. Does it show lpg or petrol consumption I have no idea. I have no idea what I have done, because I opened everything. Anyone with similar experience? strictly driving in town, small town, lots of traffic, start stop all the time,  city mode

[Raeturbo]

No idea what you done, but I wish you would do it to my car too👍👍👍👍😂😂

[Gintonic]

 

[deviator]

I wonder if this could be a failing sensor?

I will say, if the fuel economy is down and it's been serviced. Then my first port of call would be the coolant temp sensor. There are 2, one for the ECU, one for the clocks. These do fail and when they do, they cause the car to overfuel as it always reads cold.

[Doctor Gollum]

If it were coolant sensor related it would overfuel to the point of flooding it and being lpg it would never swirch over because it was always think it's cold, although this depends how it's wired... Worst case it would double fuel it, see above.

Computer only shows what it thinks the petrol consumption is. The computer cannot calculate zero, so even left idling, it will eventually cause it to drop.

Basically if your actual gas tank range is unchanged for a given literage of fuel then i wouldn't worry, especially if it is running well 

The 'economy' of lpg comes from the fuel cost, not efficiency

[STEMO]

I wonder if this could be a failing sensor?

I will say, if the fuel economy is down and it's been serviced. Then my first port of call would be the coolant temp sensor. There are 2, one for the ECU, one for the clocks. These do fail and when they do, they cause the car to overfuel as it always reads cold.

The fuel economy is up.

[Doctor Gollum]

I wonder if this could be a failing sensor?

I will say, if the fuel economy is down and it's been serviced. Then my first port of call would be the coolant temp sensor. There are 2, one for the ECU, one for the clocks. These do fail and when they do, they cause the car to overfuel as it always reads cold.

The fuel consumption is up.

Fixed... Litres per km not mpg 

[STEMO]

I wonder if this could be a failing sensor?

I will say, if the fuel economy is down and it's been serviced. Then my first port of call would be the coolant temp sensor. There are 2, one for the ECU, one for the clocks. These do fail and when they do, they cause the car to overfuel as it always reads cold.

The fuel consumption is up.

Fixed... Litres per km not mpg 

You haven't fixed anything, you've just got it wrong. 18-21 litres per 100km is higher consumption than 13-16 litres per 100 km. Dear me 

[Doctor Gollum]

I wonder if this could be a failing sensor?

I will say, if the fuel economy is down and it's been serviced. Then my first port of call would be the coolant temp sensor. There are 2, one for the ECU, one for the clocks. These do fail and when they do, they cause the car to overfuel as it always reads cold.

The fuel consumption is up.

Fixed... Litres per km not mpg 

You haven't fixed anything, you've just got it wrong. 18-21 litres per 100km is higher consumption than 13-16 litres per 100 km. Dear me 

You wrote 'economy', which I fixed to 'consumption' 

But you're absolutely correct, fixing it is up to Gintonic

[Enceladus]

I wonder if this could be a failing sensor?

I will say, if the fuel economy is down and it's been serviced. Then my first port of call would be the coolant temp sensor. There are 2, one for the ECU, one for the clocks. These do fail and when they do, they cause the car to overfuel as it always reads cold.

The fuel consumption is up.

Fixed... Litres per km not mpg 

You haven't fixed anything, you've just got it wrong. 18-21 litres per 100km is higher consumption than 13-16 litres per 100 km. Dear me 

You wrote 'economy', which I fixed to 'consumption' 

But you're absolutely correct, fixing it is up to Gintonic

The OP started with 18<=>21 litres per 100km.
He ended up with 13<=>16 litres per 100km.
So fuel economy improved, also the engine runs smoother.

[STEMO]

I wonder if this could be a failing sensor?

I will say, if the fuel economy is down and it's been serviced. Then my first port of call would be the coolant temp sensor. There are 2, one for the ECU, one for the clocks. These do fail and when they do, they cause the car to overfuel as it always reads cold.

The fuel consumption is up.

Fixed... Litres per km not mpg 

You haven't fixed anything, you've just got it wrong. 18-21 litres per 100km is higher consumption than 13-16 litres per 100 km. Dear me 

You wrote 'economy', which I fixed to 'consumption' 

But you're absolutely correct, fixing it is up to Gintonic

Except economy was right and consumption is wrong, so you didn't fix it. And it doesn't need fixing, he has fixed it.

[Doctor Gollum]

Oh yes

 

[Gintonic]

And I have no idea what did I fix exactly 
Well, after cleaning,  the ,, bad rpm sensor,, no longer shows on diagnostic so I suspect that cleaning the connector helped. Also the small vacuum that is behind the top of the engine and is connected with a small U shaped rubber hose., I cleaned that and fixed it to be in place, it was out of his place.Only thing that I don't know is where that vacuum plastic pipe that goes from it to the front of the engine where should be connected.

[Doctor Gollum]

It connects to the throttle body, underneath

[Gintonic]

If someone could share a picture, I can't find it, tried many times to find the place
Thanks

[Enceladus]

And I have no idea what did I fix exactly 
Well, after cleaning,  the ,, bad rpm sensor,, no longer shows on diagnostic so I suspect that cleaning the connector helped. Also the small vacuum that is behind the top of the engine and is connected with a small U shaped rubber hose., I cleaned that and fixed it to be in place, it was out of his place.Only thing that I don't know is where that vacuum plastic pipe that goes from it to the front of the engine where should be connected.

As I recall the vacuum hose with the U rubber connects to the changeover valve at the top back left of the plenum chamber on the top of the engine. The U is inverted when connected.

Doesn't the other end connect to the vacuum reservoir or the multi-ram valve situated in the intake air pipes at the front of the engine? Or somewhere in that vicinity.

[Doctor Gollum]

It connects to the throttle body, underneath

Multi ram reservoir vacuum lines run over the 246 cam cover. There is a guide/faq on their routing 

On the 2.6/3.2 there's a vacuum line from the throttle body to the fuel pressure regulator and is only just long enough to connect the two, and is therefore almost always overlooked. Not sure if this exists on the 2.5/3.0, so responses may be at crossed purposes 

[zirk]

Zirk's EU magic number is 282

So for reference 18 to 21 L per 100km is
282 / 18 = 15.6
282 / 21 = 13.4
Therefore 13.4 to 15.6 mpg

Like wise 13 to 16 L per 100km is
17.6 to 21.6 mpg

282 also works the other way ie
25 mpg is 282 / 25 = 11.2 L per 100km

[Gintonic]

Update, heavy rain for 3 days, driving in heavy rain, the rough running of the engine came back. So it's definitely some electrical connection going bad on rainy weather. I have no plastic protection cover beneith the engine, I m getting one ASAP, but I don't think that would make some difference

[johnnydog]

Any mention of heavy rain, and on a 3.0, would make me look at the ignition coil down the back of the engine by the bulkhead. Maybe your liberal spaying of the 'connectors' was just good fortune and a coincidence that it began to run smoothly, and the recent heavy rain has run off the scuttle and onto the coil / leads causing the actual problem to reoccur.