Running problems on LPG

[boxdog]

Guys and girls, I have a VZ Exec sedan which is running on dual fuel (has a Sprint Gas system installed). While running on gas, it's started to develop some annoying (minor, I guess) problems. It's just had its first year service on the LPG system and just before I booked it in the gas system shut down and wouldn't run at all - the LEDs on the meter flashed at me and it beeped. The guys that serviced it reckoned it had a faulty mapping sensor or something which Sprint replaced under warranty.

Soon after the gas service I noticed it would idle a little badly and when under load the engine would shudder and lose power like it was missing on a cylinder. It ran fine on petrol (I use 91 RON right now). I took it back and the guys replaced the spark plugs because they weren't done for some reason. That fixed THAT problem, but now it's still a bit crap.

Even when the engine is warm it idles a little badly when on gas. I really notice it funnily enough when the aircon is on - the car will shake at the lights because the engine is idling roughly, and then when I take off it hesitates a bit before giving me any form of power more useful than a morris minor!

Any ideas? Should I take it back to the gas guys again and complain?

[Benboy]

Guys and girls, I have a VZ Exec sedan which is running on dual fuel (has a Sprint Gas system installed). While running on gas, it's started to develop some Any ideas? Should I take it back to the gas guys again and complain?

YES - for goodness sake, TAKE IT BACK.

[poweredbycng]

Could be due to any number of different reasons. How many km's on your car? Could be a dead coil or two (remember that ignition components that are just 'acceptable' for petrol will be unsuitable for gas) or a calibration issue.

[boxdog]

Hey, well I took it back to the service guys (Rhodes and Heron in VIC, they're really good) and Perry there plugged in the computer and had a look around. He is adamant that one or more of the coil packs are shot and recommended to replace the lot. At $110 each x 6 + $77 labour that's a pretty bloody expensive proposition!!!

In the meantime he made the gas mix a bit more rich (150 up from I think 100 or 110) and it's made it even worse idling but now when I take off it doesn't seem to pause anymore.

Do you really need 6 of them? Can you just replace the dead one? Sigh...

[richardpalinkas]

you can just buy one, just ask him to replace the faulty ones. or buy one yourself and swap it around the plugs til it runs fine

[poweredbycng]

When one coil goes, it's wise to do all six of them. Once you do your plugs and/or coils, disconnect the battery for a bit to reset the ECU. Once you've done that, give the car a good run for 15min or so and you should have a pretty good base to work with for re-calibration of the system.

We have a VZ SV6 running a Sprint Gas system installed in 2007 which has never missed a beat - but then again our installer has always been top-notch...

[boxdog]

With due respect..How is it wise to pay 6 times more than you need to when they're about $110 each?? Are they consumables ie. are they expected to fail on a regular basis?

[poweredbycng]

Yes, coils are a consumable item, particularly if you're running LPG. They should last 150,000km-ish but there are no guarantees...

[JBDrifter]

I've replaced two coils in the last year after having the exact same symptoms you have experienced. Replaced one the first time, and about three weeks later I started experiencing the issues again, so replaced another coil. Has been good now for at least the last 6 months. If it happens again though I'm just going to replace the whole ignition system (all 6 coils and plugs). It was a pain both times trying to find the problematic coil.

[boxdog]

Hmm. Are they hard to change over? It's a shame they're a "consumable". FYI the car is at 102k and I installed LPG about 87k. Recently had the spark plugs done in the LPG service too. It's only stuttering on take off now and idle - not during load, which is good, but yeah..I am tempted to give it a go and buy one to try changing it but wonder if it's worth the pain

[poweredbycng]

The coils are directly on top of each spark plug.

There are also other things that may need attention at 100,000km including the combustion knock sensors and oxygen sensors, all of which tend to go at around that time and all of which have a significant impact on how well the engine runs.