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.