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Generation 4-1 Pajero NS Model 2006 - 2009

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Old 30-12-16
KrAsh's Avatar
KrAsh KrAsh is offline
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Default 2009 NS V6 - fuelling issue on lpg BIG post

Hi all, apologies for long post and maybe an unnecessary new topic but tapatalk doesn't search well enough and I'm two states away from a PC. This maybe able to be merged with another LPG thread down the track but I hope this can help myself and others.

So.....

Mystery diagnosis, 2009 NS Pajero, 6G75 V6 Auto, Duel fuel EMER vapour injected lpg. Driving from Melbourne to Brisbane, leaving Dubbo and after an hour the below;

- Heavy driveline vibration from 95-120kph whilst on LPG.
- Starts shaking in 4th and runs into 5th when converter is locked.
- Also shudders at idle.
- No throttle or converter unlocked the vibration is gone.
- ASC & TRAC off lights.

now at this point I was mentally throwing ideas in my head, something out of balance, did not think fuel to be an issue

Was initially thinking tailshaft but after some reading possibly be converter issue. We were halfway to Brisbane from Melbourne (Narrabri) which doesn't really help either but happy to push on as can drive around the vibration at a different speed.

we are still running on gas and pushing to Goondiwindi as larger town. At this point I had considered misfire, dud plug or coil as a possibility

We did stop briefly and idling it was still shaking, this led me to think converter and by process of elimination the tailshaft or wheel weights out. Anywhere above 15kph through to 90kph it revs and shifts cleanly, then starts the vibrations when TC locks up for cruise. Does flare a bit unlocking and downshifting to 4th to go up a hill or overtake, again a pointer to converter.

Now we have made it to Goondiwindi and stopped at the BP for breakfast. Car cooled a little and decision to press on is made. Again still had not considered fuel being an issue, have dropped cylinders on cars before so symptomatic of a spark or converter was culprit

Gas tank just ran out and now running on fuel, all vibration stopped and car is running like nothing is wrong. Some of my checks when I serviced the car prior to trip was a screwdriver to the injector solenoid she and all were happily clacking away. It has run fine on gas so was not even thinking that could be a problem.

I had a small cheer of joy inside that it wasn't the converter. Halfway interstate and being near new year would of had no chance of sorting out

I had a thought then as an injector may be sticky and flooding the cylinder, a week earlier 2 out of 3 cats had collapsed, possible overfuelling? BUT there has been no sign of using more than normal. So a lpg issue it is.

Process of elimination. Need to get a hold of how to diagnose and tune the Emer system. So far no DTC for misfires or the like but after some light reading LPG is more touchy to weak spark so possible we have a dud plug or injector.

made to Brisbane ok and have got onto a mate to grab plugs and a coil to do and see if can fix this issue

WHERE I'M AT NOW;

Pulled manifold and changed plugs today. One looked a little caked on the electrode but nothing to suggest spark misfire. Changed the coil on that plug as a precaution and buttoned back up. Ran great no DTC on fuel, switch to lpg and back to running rough, worse than previously, enough for CEL and the system to switch back to petrol by itself.

I have read the lpg injectors are usually only good for 200-250thou klms and I reckon are probably halfway through that as the system was installed 2011 prior to us buying and the klms from our purchase to now suggest that.

So not entirely ruling out a dicky injector, but then the thing loses power and shakes like shit so could be a total fuel starvation on all 6 which may be a blocked filter, loss of pressure, mixer issue???

Also the ASC/TRAC one is a strange thing, I know they can be triggered by a whole range of things and without a BCM reader will have zero chance of knowing why. Ours comes on at cruise 100kph and over, came on before the vibration and did when I flicked the lpg on again today. Has never come on with suburban driving, and clears when car switched off or I clear DTCs.

So that's me right now, not entirely stuffed as can still drive on fuel but do like the additional range with the lpg. Any suggestions would be appreciated at this point, won't be back home til after new year so no workshop assessment for a while.

Cheers, Ash
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Old 31-12-16
erad erad is offline
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It sounds to me as if the LPG system is running too lean. I would go to a gastune place and get them to analyse the exhaust under load. You may have an issue with the emulator. That takes the oxygen sensor signal makes the car's main ECU think it is running on petrol. Whatever, a gastune place should be able to locate the fault. Talk to a taxi driver - they know where the best tune places are. At least you can still run on petrol, but gee that hurts the pocket...
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Old 31-12-16
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Chainsaw Chainsaw is offline
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Hi Ash, LPG is hard on the ignition system this is why plug gaps are closed a bit more than when running on petrol. Have you checked your plug leads ???? To me, sounds like when the extra load is coming on the motor a lead is breaking down. You can check them with a multimeter to find the culprit or just replace the lot with a good quality set. I am on Sunshine Coast are you up near here???

Rod
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Old 31-12-16
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KrAsh KrAsh is offline
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Quote:
Originally Posted by Chainsaw View Post
Hi Ash, LPG is hard on the ignition system this is why plug gaps are closed a bit more than when running on petrol. Have you checked your plug leads ???? To me, sounds like when the extra load is coming on the motor a lead is breaking down. You can check them with a multimeter to find the culprit or just replace the lot with a good quality set. I am on Sunshine Coast are you up near here???



Rod


Hi Rod, thanks for the offer. I'm actually from Brisbane so have a few options to sort out, used a mates workshop yesterday to do the work.

The 3.8 are coil on plug, only had the one new coil to test with so we threw on the odd looking plug.

Cheers
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Old 31-12-16
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KrAsh KrAsh is offline
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Quote:
Originally Posted by erad View Post
It sounds to me as if the LPG system is running too lean. I would go to a gastune place and get them to analyse the exhaust under load. You may have an issue with the emulator. That takes the oxygen sensor signal makes the car's main ECU think it is running on petrol. Whatever, a gastune place should be able to locate the fault. Talk to a taxi driver - they know where the best tune places are. At least you can still run on petrol, but gee that hurts the pocket...


Be good if I had a cable and laptop with me, but alas never think this far ahead when all is running fine. The o2s are reading in normal range so I'm thinking is a breakdown in signal or a starvation. Sucks to be us as the Paj is a big bus and the Qld heat at moment needs aircon for the kids and us.

Will be booking it in when get home for a look, hope it's nothing too bad.
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