Cause and Solution to my problem?

[EBTom]

Hey guys, with myself not being terribly mechanically-minded, i was wondering if someone could please help me determine the cause of a problem im having.
Despite the car idling almost perfectly 90% of the time, at low speed (stop-start traffic or navigating carparks), occasionally there is considerable lag in the throttle. If you give it a bit, it will choke and splutter for a second before jolting forward.
This isnt the problem.
What i think is the problem, is when the car decides to do its choking thing in a time where harder throttle is needed. Most of the time there is a huge 'bang' from the left rear of the car. At the same time, the car immediately stalls, brakes go hard, power steering disappears, etc.
The car only does this occasionally (usually happens in spells), but it is nerve-wracking sitting in the middle of a busy intersection desperately trying to restart.
Any help would be much appreciated

[micksta]

are you running gas ?

my mates car was doing the same thing.

[EBTom]

Yep cars running dual fuel. Now that u mention it, I dont think its ever happened on petrol (not that i use it much). At first i was thinking fuel pump or something to do with injection or spark....???

[The Goodz]

Check things like spark plugs, and check that the air filter is not blocked. Otherwise I would probably get the converter checked out, could be contaminated or blocked or something.

Alex

[micksta]

when my mate gets home ill ask him what he did to fix it ... but if someone else jumps ahead with the answer .. then there u go.

i couldn't answer it now as i forgot what he did.

he went through quite a lot of panel filters because it was surging so badly.

[EBTom]

Air filters fine, current one has apparently been in there for about 20,000km according to stickers and service info in owners manual, and looks to be fairly clean.
The old man thinks the spark plugs and leads could be about due for replacing, could that be a cause of my problem?
Also, upon checking the air filter, i noticed that the top section of the air box doesnt clip into the bottom part. Guess its been broken and now held together by tape which is far from airtight. Should the airbox be airtight?

[micksta]

the more air tight it is the more its gonna want to go through the filter.

it coudln't hurt changing the plugs and leads.

speaking of which .. i need to do mine as well.

if you have the plugs and leads already .. change them now and see if theres a difference.

[Brewtal ED]

My XF had the same problem, and only in gas (although it idled really badly), turned out to be a leak in the rocker cover gasket. dunno if this is the same for E series

[EBTom]

bump?

[poomba]

all most 99.895% confident it will be the gas system mate, check converters and mixers and the like.

make sure they are not leaking, not contaminated, and water is flowing through the converter. just run it on petrol. you mentioned that it dosen't happen on petrol. so it must be the gas! are you running gas spark plugs?

if water is not or was not running through the converter, you may have frozen and warped it, or buggered the gasket. idle your car and keep an eye on it, make sure it dosen't ice up. if it does, you have a water flow problem, and resulting in an almost certain gas leak problem. if you are not to sure about gas, take it to a gas bloke.

[Kyle.L]

Check the small hose coming off the fuel regulator at the back of the engine bay. Just found that mine had a crack in it. Gives it a vacume leak and when you give it some throttle it can lean out the fuel and make it stall. If only that was the problem making mine stall all the time...

[EBTom]

Will try, thanks for the suggestions guys!

[micksta]

how did the spark plugs go mate ?

[EBTom]

Havant replaced yet but will do ASAP. Will check out fuel regulator as well, its been suggested in other threads with similar probs.
Cars gonna be sitting on king lows next week too