vw sharan misfiring

[qube]

i recently purchased a vw sharan on a 02 plate with 73 k on it. the car after a week has started misfiring and looses speed on motorway driving. when engine is turned off and on again car picks up speed but after a while looses it again. when idling the car shakes alot. taken it to main dealers diagnostic report showed electrical malfunction and apart from that they didnt know what was up with the car.

[__LEE__]

I don't think a diagnostic scanner will give you a result of "electrical malfunction" without giving a discription. ie fault / trouble code.
without a code it will be difficult to find without looking at the vehicle, and mabe some more info from you might help,
ie
is it worse when hot/cold?
does it poor idle all the time?
have you noticed high fuel consumption?
does the exhaust cat smell when the car is lumpy?
does the air induction noise become louder when loosing power?
noticed any strange engine noise when lumpy?

if you dont have any luck from the garages then mabe by process of ellimination we can help :)


I did come across a golf awhile back that had a similar fault and it ended out to be low fuel pressure

[qube]

the code given by the main dealers report was 18072 p 1664035 electrical malfunction

[__LEE__]

18072 / p1664 .. this is injection circuit problem..
my guess here is that the loss af power and the lumpy idle is caused by the car dropping down to 3 cylinders

this may be caused by a faulty injector or injector wiring

the next stage here is to try and tell which cylinder has the fault.
A close inspection of the spark plugs may help you with this.
Look for a plug that is different in color to the other 3.

[qube]

the car is a diesel i thought diesels dont have spark plugs

[__LEE__]

doh .. now you say.. :)

i have no code lists for diesels untill monday.

whats your engine code..?

[__LEE__]

thinking about it.. the trouble codes will be the same.
so still injector fault.

but i will need the engine code to advise further..Dont want to make the same mistake again :)

[qube]

the engine number is A U Y 256812

[__LEE__]

ermm hige pressure diesel.. not somthing i know much about.

but if i had the car, i guess the first thing i would do is test the injectors to see if one had a different reading. you can do this by looking for a round electrical plug to where all the injector wires join. pull this plug apart and on the injector side you will see 7 pins (all numbered on the plug). Pin 7 is the common and pins 5,3,2,6 (in this order) go to injecors 1 to 4 .
With an Ohm meter you bridge pin 5+7 to test injector 1. 3+7 to test injector 2. and so on
what you should get is 0.5 ohms across each one..

this will test the electrical part of the injector and the wires from the plug.

mabe sombody else can advise on any further test you can carry out as i have very little knowledge on this system

on a saftey note.. i do know that if a jet from an injector was you hit you.. you will proberly die.. so take care with the 30,000 psi jet