Vectra LPG Duffer Part 3, Please HELP, ECU warning P0170 mixture too rich

Sorry have to repost this as a new topic as I want to cross post this
to other groups.

5 weeks ago i bought a Vauxhall Vectra 02 Model (last of old shape) LPG
factory fitted. Engine Z18 XE, 1.8 sfi factory fitted LPG.

After experinacing a few problems documented in here at a cost of
almost £300 I have had fixed or replaced :

1] Thermostat including its housing and sensors, (£150 labour and
parts)
2] Lambda Sensor at the front of the engine (£100 labour and parts)
3] Brake switch cleaned and reset a (£40 labour)
plus (£25 per diagnostic reading)

The costs were met by the sellar who is a car trader.

However after all these fixes and diagnostics I still get a ecu light
coming on!


The reading given is:
P0170: mixture Rich.

This usually comes on after 100 miles after reseting the previous P0170
code.

The reading from the exhaust lambda is bang on 1.0 (ie perfect).
The O2 bank is switching between 0.2volts and 0.8volts (this again i am
told by the mechanic is spot-on)
he cant fully explain the problem.

The mechanic who is no gas expert believes the problem is a minor
glitch when switching between petrol and GAS the car seems to get
confused and there is nothing to worry about.

Fuel efficency on petrol seems OK. But on GAS im getting 4 miles to the
litre.

On gas i have noticed a reluctance for the car to move especially when
switching gears, i have to push the accelarator a bit more to make it a
smooth transition between gears. Even a small (what appered to me, and
i'm a little ignorant) backfire. The light seems to come on around the
time i turn on the iginition, or when im driving at random.


Its costs the sellar a fortune should I hand the car back to the
trader? or should I carry on? As always any help for the actual
mechanical / electrical problem is welcome.

 

Sorry have to repost this as a new topic as I want to cross post this
to other groups.

5 weeks ago i bought a Vauxhall Vectra 02 Model (last of old shape) LPG
factory fitted. Engine Z18 XE, 1.8 sfi factory fitted LPG.

After experinacing a few problems documented in here at a cost of
almost £300 I have had fixed or replaced :

1] Thermostat including its housing and sensors, (£150 labour and
parts)
2] Lambda Sensor at the front of the engine (£100 labour and parts)
3] Brake switch cleaned and reset a (£40 labour)
plus (£25 per diagnostic reading)

The costs were met by the sellar who is a car trader.

However after all these fixes and diagnostics I still get a ecu light
coming on!


The reading given is:
P0170: mixture Rich.

This usually comes on after 100 miles after reseting the previous P0170
code.

The reading from the exhaust lambda is bang on 1.0 (ie perfect).
The O2 bank is switching between 0.2volts and 0.8volts (this again i am
told by the mechanic is spot-on)
he cant fully explain the problem.

The mechanic who is no gas expert believes the problem is a minor
glitch when switching between petrol and GAS the car seems to get
confused and there is nothing to worry about.

Fuel efficency on petrol seems OK. But on GAS im getting 4 miles to the
litre.

On gas i have noticed a reluctance for the car to move especially when
switching gears, i have to push the accelarator a bit more to make it a
smooth transition between gears. Even a small (what appered to me, and
i'm a little ignorant) backfire. The light seems to come on around the
time i turn on the iginition, or when im driving at random.


Its costs the sellar a fortune should I hand the car back to the
trader? or should I carry on? As always any help for the actual
mechanical / electrical problem is welcome.


Weigh it in boy.

 

The fault codes you are reading are from the petrol ecu.
The LPG ecu is a separate unit and has its own set of fault codes. This
can't be read by the usual scanner but needs something called monio, a DOS
based system that Vauxhall only supply to registered LPG repairers.
Monio gives fault codes and live data just like the petrol ecu scanners.

Also there is a little black box fitted called R1, it is a "trickbox" -
fooling the petrol ecu into thinking the engine is still running on petrol
by giving false reading to the petrol ecu when the car is on gas - this
stops the management light coming on.

It may be an idea to see if your supplier would pay for the cost of a monio
check at a Vauxhall dealer to see what is going on and what fault codes are
present in monio. You would need to find a Vauxhall dealer that does LPG.

Hope this helps

 

Sounds like the factory fitted LPG is a bodge. They should have re written
the ECU to do both (just another set of lookup tables?), rather than bodging
the LPG ECU to fool the petrol ECU into thinking the world is running fine.

Bob

 

Vauxhall build the cars and then transport them to a company called
Millbrook who install the LPG systems.
Most companies do it this way - build car first and then add LPG. I guess
it isn't cost effective to tool up a production line to build LPG vehicles
cos of all the different models involved.
Vauxhall do build a Zafira that is gas first and petrol second but that is
compressed natural gas (same as your house) not LPG. Never seen one but lots
in Europe I am told - has 4 huge gas bottles under the floor as tanks.

 

"> Vauxhall do build a Zafira that is gas first and petrol second but that
is

Really? I never knew that. does that mean that dual fuel zafs are vitually
non existant here in the uk because of lack of refuelling facilities?

Mike

BTW, I do remember -trying to stay a bit on topic for the thread- that the
guy who did my first ever lpg conversion (range rover) had just finished a
1.8 vectra taxi, and swore that he would never do another on as long as he
lived as it had been so much trouble. unfortunately, if he said why I cannot
remember, and it may have just been him personally. Another bit of trivia I
remembered is that he told me that 2.0 omegas converted nicely but 2.5's
didnt. sadly, again no reason..

Mike

 

Lots of LPG Zafiras but never seen a CNG one yet - or any where to fill one.
Some council - can't remember which - had a couple of CNG Combo vans as a
pilot scheme test but filling time was 8hrs so it never caught on. They
must have overcome filling time problems in Europe or you would be sat at
filling stations all day.
Vauxhall raced a 2.5 V6 Vectra B on LPG for a while but have never had
anything bigger than 1.8 in production models

 

If it is natural gas, I would think you get a compressor fitted in your
garage, and leave it connected to the gas mains overnight.

Bob

 

Now I think about it, I do believe I've seen a couple of CNG artics up and
down the motorways. they do say CNG, not LPG. by accounts i've heard,
drivers dont like them. something about overheating, but I've never
drivenone myself.

Mike