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Cold starting

Hi I have a problem with my wife's 08 plate 1.5 dci the red engine warning light came on the other day .I plugged it in an got this fault code p0670
Glow plug control module open circuit so after some digging I replaced the module and cleared the fault code
but the light is still on and it's a bugger to start when cold loads of smoke and runs lumpy till its warmed up after that it's fine
Any idea's

Cheers
 

frank

Club Member
never owned a dci tbh, looks pretty straight forward tho, youtube vid or dci forum how-to ?
 

frank

Club Member
yes thats normal on most diesels, my cdti would pre glow for 1 sec (longer in winter) then the voltage slowly dropped for the next 2 or 3 mins (afterglow mode)
some generic code readers give false codes, or manufacturer specific ones
 
So if the glow plug system is working why is it hard to start and when it does I get smoke and lumpy running until it warms up could it be a faulty injector?
 

frank

Club Member
low compression maybe ? my hdi smoked and had a lumpy idle till i cleaned the carbon out of the inlet mani, always started ok tho

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I doubt it's that as it wasn't a gradual thing the engine warning light came on and that's when the problem started it's just when it starts from cold I've tested the glow plugs for resistance by attaching my multi meter com tip to engine bloc the red on the tip connector of the plug and the for voltage red to battery + the com to plug tip is this the right way?
 

frank

Club Member
yes i,ve always tested them with an ohm meter with the bus bar off (between threaded nut and earth)
and then a voltage check on the bus bar when keyed
 
Do you pre heat the glow plugs before you actually start. Because this can help with starting problems in the cold on common rail engines. Such as turn the key warm the plugs turn back off then turn to reheat then start.
Was shown to do this on a tdi golf when it got snowed in one year.
also a newer battery.
Hope this helps
 
That seems to help but still getting smoke and lumpy running till its warmed up I don't think the plugs are coming on for long enough I have replaced the relay too I'm stumped now
 
Does the car get long runs to blow the carbon out. As far as I know the smoke can mean a bad turbo if one is installed on a dci not sure.
The blow out of exhaust is something you would have to do in a higher gear like third and at a slightly higher rpm but that may not be something you would wish to do. Might help in the future I heard this helps to lower the readings for emissions.
This could however be performed after an engine flush every so often.
Also the glow plugs might not be functioning correctly..
I think also you should consider cleaning the manifold as frank shows above.

Maybe someone else has much more technical advice for you.
Missing the common rail Volkswagen now :(

Good luck with this :D
 
It runs perfectly fine once it has warmed up no lumpy idle Loss of power or smoke
I've booked it in at a diesel spcialist as I'm stumped now it could be any number of things
 

frank

Club Member
maybe egr stuck open ? most diesels have the egr fully open at idle, but probably not from cold tho
 
I've tested the glow plugs and I'm getting 00.6 ohm and 12.27 v same voltage as the battery I'm getting a constant 5.67v from the leads then on ING I'm getting around 10v for a split second before it drops back to 5.67v again I've replaced the relay any idea what i could test or check next it's got to be something in the glow plug circuit as it runs perfect when it's warm
 

frank

Club Member
strange eh, but a healthy dci should cold idle ok without glowplugs at all, in all but the coldest of weather.
my 2.0 hdi started and idled perfect when i re-wired the glowplugs to a high amperage switch (disconnected the expensive busted relay) i never had cause to switch them on in the end, and that was right down to -5deg c
 
Got to the bottom of it!!!! took it to a diesel specialist the ecu was up the chute the programming was all messed up so after the injectors were cleaned and tested the ecu was re programmed runs great now just wondering what could have caused it
 
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