Powertrain warning light on LPG

Tiny
BOA69
  • MEMBER
  • 2006 HOLDEN COMMODORE
  • 3.6L
  • V6
  • RWD
  • AUTOMATIC
  • 130,000 MILES
I have a 2006 HOLDEN VZ V6EXECUTIVE 3.6L ALLOYTECH which has an aftermarket SPRINT LPG system installed (it also runs on Unleaded Petrol)Dual Fuel). ONLY when running on LPG and under load at about 2000rpm the "CHECK POWERTRAIN" warning light comes on dash and the engine runs like its dropped a few cylinders until I switch engine off, then when started the light disappears and it runs fine until under load again. ""THIS ONLY HAPPENS WHEN RUNNING ON LPG""
I had a GSCAN fault tool hooked up to it and it showed the following error codes and messages:

P0300 - Random/Multiple Cylinder Misfire Detected.
P0304 - Cylinder 4 Misfire Detected.
P0443 - Evaporative Emmission Control System Purge Solenoid Circuit.
P1632 - Immobiliser Transponder Response Distorted.

Can you give me any information as to which parts I should replace first to fix these faults?

Will it hurt the engine if I keep driving with these faults in the system?

Which Spark Plugs should I use (will NGK-R BPR7EFS-15 be ok) and the recommended Spark Plug Gap (1.1mm)?

I have recently done all repairs listed below:
Replaced the Air Filter
Cleaned MASS Sensor
Cleaned Throttle Body
Cleaned Intake Manifold & Plenum
Replaced Engine Oil + Filter
Replaced Heater Control Valve
Added Injector Cleaner to Unleaded Fuel
NONE OF THESE HAVE FIXED THE FAULTS

Today I plan to replace the Spark Plugs & Plenum/Intake Manifold Gasket and inspect the 6x Individual Coil Packs a bit closer.
ANY HELP - INFO OR ENGINE DIAGRAMS WOULD BE GREATLY APPRECIATED.

THIS ONLY HAPPENS WHEN ENGINE IS RUNNING ON "LPG" & HAS NEVER HAPPENED WHEN RUNNING ON UNLEADED PETROL
Friday, December 25th, 2015 AT 7:32 PM

5 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Replace the coils and plugs, LPG has a higher flash point than petrol that is it takes more energy to ignite so a misfire will show up on lpg before petrol, this is a fairly common problem.
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Saturday, December 26th, 2015 AT 2:35 PM
Tiny
BOA69
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Thanks for your reply MHPAUTOS, Is it ok to replace just 1 coil pack or should I replace all 6 together? Its just that I cant afford to buy all 6 of them in the 1 go, repco wants $235.00 for the 6 of them, does this sound right?
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Saturday, December 26th, 2015 AT 6:07 PM
Tiny
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You can do them one at a time, no problem, that price is about right for retail, just do the one that's a problem now, but be prepared to replace others down the track.
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-1
Saturday, December 26th, 2015 AT 8:16 PM
Tiny
BOA69
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  • 34 POSTS
Cheers for your replies MHAUTOS, I have finally fixed the faults, I replaced the spark plugs to a plug with only a 1.1mm gap - replaced cylinder no.4 coil - replaced Plenum Gasket - disconnected the battery to reset the computer. I have now done over 300kms on LPG and the faults have not re-appeared. I think the plugs in it were wrong because they had a gap of about 2.5mm which seems way to big I think.
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Tuesday, December 29th, 2015 AT 10:58 PM
Tiny
MHPAUTOS
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Plug gaps are very critical, the 1.1is the correct gap.
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Thursday, December 31st, 2015 AT 5:00 AM

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