Bought a 2006 380 with 138xxx on the clock about a month ago.

When idle (and at take off until you get up to around 10km/h) in drive or reverse on LPG - the car shakes gently with what I guess you'd call misfires. No such problem in park or neutral but gets severely worse while the A/C is on (to the point where the car is pretty much undriveable on LPG) and while turning the steering wheel. Unleaded fuel has no such problems and runs smooth as.

I've had it in at a gas workshop where they did:

- gas filter change
- air filter change
- calibration on LPG computer
- fixed a leak at the filler
- spark plugs replaced with NGK Iridium IX BKR5EIX-11 all round
- spark plug tube seals + rocker gaskets replaced

These steps haven't fixed the problem.

What's next? On my old V6 Magna - I had similar issues (but this was a petrol-only car), and replacing the battery fixed it. Could this be the same case here? I really hope that's all it is - but the battery doesn't look that old (but I can't find a receipt in glove box, whereas most invoices from previous owner(s) are there).

I'd doubt it to be the battery, as once the car is running, the alternator is provided electrical power, not the battery.

A lot of those things may have needed replacing regardless, but it's strange that a lot of those things were done when the thing runs perfectly fine on petrol?

It's pretty hard to diagnose something like this over a forum. Firstly, you said it shudders badly and feels like it misfires... You really need to determine if it's actually misfiring, or if it's just a bad shudder which feels like a misfire.

First step... Have you had the ECU error codes read? The 380 ECU can log persistent misfires (and even which cylinder it is occurring on).

It could be the battery, there are lots of threads on here about the weird and wonderful things that happen to 380's when the battery is on the way out. Strange that it doesn't happen on petrol, but i'm no LPG expert.

FYI - alternators charge the battery and the battery supplies the power. So yes, even if you have a good alternator and a crap battery it will still cause problems.

I have an OBDII code reader coming, but it hasn't arrived yet and I haven't taken it back to the mechanic as of yet because I'm broke and busy!

Would a misfire physically shake the car in a backwards direction or is that a back fire? I don't know the difference. It doesn't make much of a noise though! It's just a physical backwards shake and the revs drop at the same time.

First of all, you should have gone back to the GAS place not another mechanic. Also, is this gas place IMPCO certified or a dealer, you need to make sure you go to an IMPCO dealer (assuming is IMPCO system as fitted to many of these)

The work the mechanic did has NOTHING to do with the issue. The spark plugs are wrong for starters, the 380 takes a 6 series spark plug, not 5 series plug, especially with LPG

We have had a couple of these doing the same issue, I do not work on LPG personally but I know someone who does and these were referred to me by IMPCO, issue was with the software and the O2 sensors, they ended up having the programme for the LPG bypass the O2 sensors (only when on LPG) for both these cars and the issue was fixed.

Also, flyboy, not having a go mate but the battery provides the power to run the car NOT the alternator. The alternator simply keeps the battery charged, if you have a battery drop a cell when driving the car will come to a sudden stop, I have had this happen to me in the past as well as customers. Yes, you can unplug the battery, risk blowing your electrical system from a surge and run the car with no load BUT generally speaking the battery is what keeps the car supplied and the alternator keeps the battery supplied

In this case I would not say battery as the issue is not present on Petrol, only an issue on Gas.

Bradhook,

Yes, there are lots of threads on here about the 380 battery - check and you'll see I've been involved in a lot of them.

FYI - your statement that the alternator charges the battery and the battery provides the power is dead wrong. Once the car starts, that battery does nothing other than
1. accept charge to recharge itself - which happens in a matter of mins, or even seconds
2. In laymans terms, if there is a fault or voltage transients from the alternator - will help smooth them out - sort of like a shock absorber

100% of the power used to run the entire car is provided by the alternator as soon as the engine is running (unless you have some weird extreme low idle or voltage regulator problem).

The reason a faulty or high resistance battery causes the 380 problems is because the ECU is very voltage sensitive - if you jump in and hit the starter straight away, the start will pull the battery voltage down very low (below say 9 or 10V) and as the ECU and all the attached sensors initialise, they don't respond properly and causes issues.

Older cars' ECUs were simpler, required less power - and were less susceptible to transient voltage drop during starter engagement.

Right, so now that's sorted....

Have you had the ECU codes read?

Thanks for your reply Mal!

The workshop I go to is a large one that has individual departments. They have a specialized gas workshop, a normal workshop, a restoration workshop, and have a painting booth.

This same workshop is one that Mitsubishi contracted to install LPG systems from brand new, and they are IMPCO certified.

Might just drive it on petrol for now until I can afford to have it looked at again. I may go to another gas workshop this time, even though these guys are pretty reputable around Adelaide for gas.

Hi Mal.

I'm not having at go at you either, because everyone knows you are the Mitsi guru. But the battery does not supply power to the car. It flat out absolutely does not. Go and ask ANY electrician or auto electrician what supplies electrical power to the entire car once the engine is running, and they will tell you the alternator. The battery recharges (very quickly in fact), smooths out voltage transients (such as from an extremely low idle or voltage regulator problem).

Discussing what happens when disconnecting a battery from a running engine or a battery dropping a cell does not prove your point. All it does is prove my point that the battery acts like a shock absorber from voltage transients. Take the battery out, and the voltage regulator will struggle to regulate voltage during load change, and you can get big power spikes which will fry things like your ECU and even the diode pack in the regulator, and most importantly on most modern setups, the field excitation to the alternator is lost and the alternator can not produce power.

You can not put power into one side of a battery and take it out of the other side. A battery either provides power (such as when the engine is off or during start), or absorbs power when recharging. It doesn't do both. To do so would require a rewriting of basic electrical theory and physics.

As I said, I'm waiting on my code reader as I don't have any time or money at the moment to take it back to the shop.

I never argued with you about what supplies the power flyboy - you must have got the poster wrong. ;)
Kinda doesn't explain how my Magna with a similar issue was fixed by replacing the battery though, but honestly I have no idea of anything electrical, and only basic knowledge of cars.

But yeah, I'm not the expert - just thought the battery might have been worth a mention to try and get people's opinions.

Mitsifix is right.

The battery provides the source of DC voltage to run the car, 100% of the time and forms part of the closed loop voltage regulation circuit.

The alternator keeps topping up the charge to maintain voltage at the battery....not directly to any load whatsoever.

All vehicle functions derive power directly from the battery.

But to the original fault (as i don't think it is the battery...LOL)

The Impco S56 system uses drilled injector extension nozzles in the plenum, they can block or break as they are very fragile...(I have had this cause I damaged one.)

Also there can be a leak in the injector rail or ONE of the injectors can fail or bind....easy fix...just substitute the rail and go for a drive.

That's where i would be looking...

What something is directly connected to, and what is providing the power are two completely different things.

Let's draw a picture, where O represents a part of the electrical system, and the ----- represents electrical wiring (although this greatly over simplifies an car wiring system).

O------------O-----------------------O
Alt. Battery. Electrical consumer (such as starter motor, headlights, radio)

The electrical consumers connected to the battery are not being powered by the battery. PERIOD. It is being powered exclusively by power from the alternator. The battery is there as a source of power when the engine is off and to smooth transients. It powers nothing when the car is running. It's just like an accumulator in a hydraulic system.

The reason the car will stop when the battery is removed is because there is no field voltage for the alternator.

Anyway, we are going around in circles, and as I said in the original post, I don't think it's battery either.

Get the codes read when you can, and consider sending a PM to Zilo as he might be able to refer you to an IMPCO specialist.

nice zeros.

when i did my apprenticeship i was always told that the battery provides the power and the alternator provides the charge to keep the battery charged up. this is how your alternator can die but you can still run your car, headlights etc to get home - until you drain the battery.

Flyboy, lets not get into arguements here, I know you are some sort of aeronautical engineer, from my basic flight training many years ago in a plane, well light plane anyway, the magneto provides power for the aircraft and the battery is simply there to start it, thus why you can hand start an aircraft.

With a car, this is not the case at all, a bad battery can even have the ability to crank the car perfectly normally but not start the car as the crank voltage can drop too low and with the reduction drive starters we have these days it takes a lot less to crank a car than it used to. When the battery is dead you can not even push start the car :) The reason a car will sometimes still run when the battery is disconnected is because the field is still there in a way of sorts, the charge cable is coming onto the main terminal of the battery. I have seen some cars, Magna's being one of them that will run with the battery disconnected BUT the risk of a voltage spike is huge and add to this it can destroy the alternator as well. On a lot of newer cars with IC controlled regulators which use the ECU as part of the voltage regulation this will not work.

John is right about the injectors, have also seen this. This is why I suggested going to a proper IMPCO tech and not just going to bobs red hot gas installations down the road.

You will most likely not get codes either when the issue is just LPG and not petrol as well.

And BTW John, it is Mits-Fix :)

I haven't read most of the thread, but I have an idea, thinking outside of the square.
When I have had shuddering in-gear at idle in my third gens, the culprit has often been engine mounts. Check them for visible splits and/or deterioration.

Once again I may be mis-interpreting your issues.

What something is directly connected to, and what is providing the power are two completely different things.

Let's draw a picture, where O represents a part of the electrical system, and the ----- represents electrical wiring (although this greatly over simplifies an car wiring system).

O------------O-----------------------O
Alt. Battery. Electrical consumer (such as starter motor, headlights, radio)

The electrical consumers connected to the battery are not being powered by the battery. PERIOD. It is being powered exclusively by power from the alternator. The battery is there as a source of power when the engine is off and to smooth transients. It powers nothing when the car is running. It's just like an accumulator in a hydraulic system.

The reason the car will stop when the battery is removed is because there is no field voltage for the alternator.

Anyway, we are going around in circles, and as I said in the original post, I don't think it's battery either.

Get the codes read when you can, and consider sending a PM to Zilo as he might be able to refer you to an IMPCO specialist.


Listen flyboy I've had an electronics engineering degree since 1984.

That's probably longer than you have been alive.

Trust me when I say you are completely, utterly WRONG.

I also own the Impco LPG diagnostic laptop, dongle and application software....so I know the 380 LPG system intimately.

.

Haven't had the car checked out as of yet, but it is now misfiring on ULP too - just nowhere near as severe as when on LPG. :(

OBD scanner is showing a different cylinder misfiring every time I clear the codes - it's never the same error that comes back.

It's currently on P0305, but previously has been P0301, and P0302 and I have a 'DTCStatus' of "errorMIL: off Spark Ignition".

I also have a 'U1120 - Network' error that sticks around even when cleared, but for the life of me - can't find anything about. Anyone got any ideas? Could this be related?

http://s25.postimg.org/ov2lbw8n3/flyhome.jpg


So much complicating this thread when it's not needed.


I would look at other things.. a miss on gas over petrol does not make sense. If anything I would think that the presence of the knock sensor would help prevent things like this unless a standard ignition part was faulty.

Haven't had the car checked out as of yet, but it is now misfiring on ULP too - just nowhere near as severe as when on LPG. :(

OBD scanner is showing a different cylinder misfiring every time I clear the codes - it's never the same error that comes back.

It's currently on P0305, but previously has been P0301, and P0302 and I have a 'DTCStatus' of "errorMIL: off Spark Ignition".

I also have a 'U1120 - Network' error that sticks around even when cleared, but for the life of me - can't find anything about. Anyone got any ideas? Could this be related?


U1120 is centre console display error...you probably dont have one (a base model 380?)

Flyboy is right, alternator is what drives the electrical components not the battery, whether you can run the car with the battery disconnected is irrelevant. Battery has 2 functions, 1: being well a battery i.e. storage solution 2. yes a shock absorber to even out voltage fluctuations, as the demand for power constantly changes. Battery charge only occurs when it can, i.e. when volage potential is higher at the alternator side, the current cant flow the other way due to diodes, as it is possible to have it the other way. What he was saying is that the alternator drives the car which is correct, not whether it is safe or advisable to drive the car without the battery.

Flyboy is right, alternator is what drives the electrical components not the battery, whether you can run the car with the battery disconnected is irrelevant. Battery has 2 functions, 1: being well a battery i.e. storage solution 2. yes a shock absorber to even out voltage fluctuations, as the demand for power constantly changes. Battery charge only occurs when it can, i.e. when volage potential is higher at the alternator side, the current cant flow the other way due to diodes, as it is possible to have it the other way. What he was saying is that the alternator drives the car which is correct, not whether it is safe or advisable to drive the car without the battery.

Rubbish.

Run the car on LPG at idle, disconnect the LPG injectors one by one... see if the make s a diiference, should highlight a blocked/faulty injector..


As for the battery powering a car...
If I fully fulled the magna, both tanks, she'd nearly get from Bris to Albury...

If I started the car, then disconnected the battery, and drove, how far would i get in one drive...
The If I started and disconnected the alternator. How far then...

Us audio guys usually do the big three...
Power flow from and to the Alternator, via Engine/Chassis/ Battery earths. and Power Alt to Batt +..
As when a car is the off the earth is the Batt Neg.. On a running Car, the earth is the Aternator Case, you cant really earth that so, as its mounted to the engine block, we use that instead...

These F1 guys know the drill...
https://www.youtube.com/watch?v=al6Yz3Nv7dY

or
http://www.firestonecompleteautocare.com/cf/batteries/your-cars-electrical-system/


A car battery with a dropped cell will stop a car, only coase it will probably cook the alternator...

Batteries are good buffers from the alternator though... As is, strangely, a Cap, placed before a Tweeter amp, can do marvellous things for the treble...

Haven't had the car checked out as of yet, but it is now misfiring on ULP too - just nowhere near as severe as when on LPG. :(

OBD scanner is showing a different cylinder misfiring every time I clear the codes - it's never the same error that comes back.

It's currently on P0305, but previously has been P0301, and P0302 and I have a 'DTCStatus' of "errorMIL: off Spark Ignition".

I also have a 'U1120 - Network' error that sticks around even when cleared, but for the life of me - can't find anything about. Anyone got any ideas? Could this be related?


Only time mine misfired on LPG the Oxygen sensor was the culprit - did u get any codes related to oxy sensors?

Rubbish.

Very constructive argument as usual. Thank you.

Yeah, I have just the ES variant - so that's the U1120 sorted. Thanks for that Zilo.

I replaced the battery with a new higher CCA one just as preventative maintenance and it didn't change my misfire.

I'm starting to think it's an ignition fault as sometime it turns over oddly, on top of the misfiring. Wouldn't the mechanic have checked for potential problems while I had it in for plugs and plug gaskets (among other things) though? I mean, I did go in there saying it's misfiring after all. The plugs didn't fix anything and I left and it's still misfiring.

I would swap over the crank angle sensor.

Check if the signal wire is cut where it transitions between the two timing belt covers.

I just went out and checked the signal wire and it looks in good shape. Definitely isn't crushed, cut or split - nothing out of the ordinary. I unplugged it, cleaned the grime off and replugged it back in just to feel like I did something, but it didn't help.

I see I can get the part for $100-125. Happy to spend that to try and fix it! Doesn't look like a job I'd be confident in doing myself though. How much labour do you think a mechanic would charge to get at it?

Have you checked the coils

Sometimes the simplest of problems can get over complicated, only because we let crazy ideas run wild in our minds.

It probably will end up being something simple like incorrectly gapped plugs, dodgy ignition lead or something.

A few months ago my brother had gotten all his plugs changed over and he got it back for not even a few days and a severe miss fire developed. He couldn't even get it back to the mechanic so after a couple of hours I had checked all 6 plugs and found that at least two of the leads were intermittent on a simple continuity test.

My guess is that the leads were so old that when disturbed something went wrong in the matrix. Thus unraveling the mysteries of the universe. So I replaced the leads with a spare set that I knew were working, and it ran smooth as silk again. He had theories that he had put some bad fuel in and he had blown the engine up or some crazy idea.

So, did they check the leads for you? What else did they check?
When did the issue start? What changed prior to the issue starting?

I don't think they have leads ..COP ...coil on plug



Sometimes the simplest of problems can get over complicated, only because we let crazy ideas run wild in our minds.

It probably will end up being something simple like incorrectly gapped plugs, dodgy ignition lead or something.

A few months ago my brother had gotten all his plugs changed over and he got it back for not even a few days and a severe miss fire developed. He couldn't even get it back to the mechanic so after a couple of hours I had checked all 6 plugs and found that at least two of the leads were intermittent on a simple continuity test.

My guess is that the leads were so old that when disturbed something went wrong in the matrix. Thus unraveling the mysteries of the universe. So I replaced the leads with a spare set that I knew were working, and it ran smooth as silk again. He had theories that he had put some bad fuel in and he had blown the engine up or some crazy idea.

So, did they check the leads for you? What else did they check?
When did the issue start? What changed prior to the issue starting?

I don't think they have leads ..COP ...coil on plug

Oh yea, then again my brother has a shuddering issue on his BA falcon and it was a coilpack. He also had a misfire which turned out to be a dodgy converter.

Yeah, 380's don't have leads and the LPG system is vapour injected, so no mixer either. Had the LPG system completely looked over, plugged into computer and serviced and was told it was all fine.

Not incorrect gapped plugs. New and old (factory fitted) plugs both misfired.

No codes for oxy sensor, and my scanner shows they all appear to be working as usual (AFAIK).

Coils might have to be looked at. Just don't have the money right now do really do anything.

I just went out and checked the signal wire and it looks in good shape. Definitely isn't crushed, cut or split - nothing out of the ordinary. I unplugged it, cleaned the grime off and replugged it back in just to feel like I did something, but it didn't help.

I see I can get the part for $100-125. Happy to spend that to try and fix it! Doesn't look like a job I'd be confident in doing myself though. How much labour do you think a mechanic would charge to get at it?

It entails taking both plastic timing belt covers off...the crank pulley has to come off to get lower plastic cover off, power steering belt has to come off...then sensor comes off.

I can do it in an hour but I have done it many times.

Your mechanic may take two...

I am just thinking...LPG....hmmm...you might have a blocked catalyctic converter?


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