duel fuel alloytec still hesitating only on gas

[mattyr82]

so this is the run down of my missus vz. its an exec wag alloytec on duel fuel dec 2006. 115k
was driving fine, for the first few weeks we had it always running on gas, then she tells me it hesitated when taking off, i took it for a spin and floored it and it s&*t itself, "check powertrain" and ran rough....turned car on and off and its fine again.
changed all 4 O2 sensors.....took it for a hard drive and was fine on both fuels even flooring it multible times, as was not the case previously. next day hesitating again.
changed s/plugs bosch platinum gapped 1.1mm, a/filter, f/filter, genuine 10w-30oil and filter. cleaned throttle body and new intake gasket,sprayed gas injectors with throttle body cleaner when manifold was off, and disconnected battery for 30mins and pumped brakes 30 times(as instructed by forum member, to remove ecu memory...???)
took for a spin drove real hard on both fuels and it was excellent heaps of power more responsive, goin great......next day missus tells me hesitating on gas, day later still hesitating and also "check powertrain.
i took it for a spin and started stuttering or hesitating as soon as i put into drive after reversing out driveway, took off and still hesitating on and off flicked to petrol and gave it to it......PERFECT so now only running on petrol, WTF!
Only thing i can think is that maybe blocked gas injectors, or cracked rubber hose that leads to injectors, as i had to bend them out the way to get coils off.
or coils, but why does it still go good on petrol? really need help please
also mainly seems to do it either taking off, or accellarating up from around 50km/h to 70km/h. went alright this morning from 80-150km/h on gas.

[Trent L]

I know nothing about LPG set-ups ....... but can remember reading similar posts (might have been yours).

Sounds like you need to find a friendly Holden Dealeship that is open, drive it hard to force the 'error' and without turning the engine off, drive straight back to the Holden Dealership to plug in a Tech2 & read the fault codes.

[mattyr82]

after talkin to my cousin last night, beginning to think s/plug gap, as the s/plugs i removed clearly had a larger gap than the 1.1mm i put in.
he said he's ea fairmont ran crap on gas until he changed the gap and it was fine. hmmmm

[strgas]

which brand of gas system is fitted ?

[poweredbycng]

The smaller electrode gap will make the engine run BETTER on gas than a larger gap.

Have you checked the condition of the ignition coils? How's your battery holding up? Have you had the gas system recalibrated? Have you replaced the gas vapour filter every 20,000km? Have you tried performing an ECU reset after replacing spark plugs?

[mattyr82]

which brand of gas system is fitted ?

BRC gas equipment is written on a few of the parts under the hood. i think it might be factory cos it says on the gas compliant plate. reg: "new oe". so prob wasnt registed yet. car was built in dec 2006 and gas compliant plate says installed 17-1-2007

[mattyr82]

The smaller electrode gap will make the engine run BETTER on gas than a larger gap.

Have you checked the condition of the ignition coils? How's your battery holding up? Have you had the gas system recalibrated? Have you replaced the gas vapour filter every 20,000km? Have you tried performing an ECU reset after replacing spark plugs?

thanks for the reply mate, ignition coils appear ok, but dont know how to tell.
battery is perfect its a deep cycle optima.
from here on as pauline hanson would say"PLEASE EXPLAIN", recalibrated?, where is gas filter and can i change myself?, how do i reset ECU. cheers mate.

[kj0]

Have you checked your sensors? Have you checked out the error code the powertrain is throwing at you?

[poweredbycng]

thanks for the reply mate, ignition coils appear ok, but dont know how to tell.

The first thing to look out for is signs of spark leak, which shows up as white lines on the coil boots. Otherwise, you'll need to take the car in to a mechanic who has the appropriate equipment to test coils.

recalibrated?, where is gas filter and can i change myself?, how do i reset ECU. cheers mate.

The LPG system has its own computer that stores calibration data. In order for the system to operate most efficiently, it is recommended that the system should be calibrated once every 12 months.

The gas filter is installed in-line between the vaporising regulator and the injector rails.

To reset the ECU, just disconnect the battery for a few hours. You'll need to have your stereo unlocking code handy.