DJSteve

smoke when cold and slight smoke on hard acceleration

4 posts in this topic

DJSteve   

hello all, my first post here,

just got a curious question im hoping someone can help answer.

i apologise for the long post but ill try and give as much info as possible, i have recently bought a 2003 320d with the eu3 m47tud20 engine, car drives lovely with exception of a few wear and tear items i need to do (brakes and a wheel bearing mainly), but when i bought the car the previous owner told me it needed injectors coded as 2 had been changed, now thats not a problem to me i thought as i have a inpa cable etc so should be able to code them no problem at all. until i got all the injector codes and found that the 2 'new' injectors were from an eu4 engine so cant be coded, again not a problem so i went out and bought 2 eu3 injectors (second hand which yes i know is a baddd idea) and replaced the two eu4 ones. got both injectors coded to then find out one is way out of spec so was causing excessive amounts of smoke during driving. so i removed that injector and replaced it with the eu4 again for now. this fixed the excessive smoke problem, but then when i accelerate hard i do get black smoke,  i then unplugged the vaccuum line to the egr valve and temporarily blocked it off (i need to better cap it should i leave it unplugged long term) and that seems to have all but got rid of smoke except under very hard pulls which i still get  a little soot but no big clouds now.

just wondering if this sounds like an egr stuck open/closed or something worse. i do suspect the soot i currently get is down to the incorrect injector presently fitted.

 

also i do know that the pipework from the intercooler to egr tends to split but can anyone advise what the best way to check this is as my top hose into egr is very soft but i dont know if thats normal(last car i had with a variant of the m47 in was a rover 75 which is a slight different layout for pipework)

 

again sorry for the long and hard to understand post :)

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I’m assuming you know that an EGR bypass is an mot fail, but deleting it is the done thing to keep engines of this vintage running well.

Can you get the wonky eu3 injector refurbed?

My understanding of pre DPF diesels is that they will all have visible smoke under certain conditions, such as cold start and WOT. However this should be minimal and light in colour. 

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B.Merr   

Agree with incredirog, in that these engines will always kick out black smoke under load.

Do you see the engine management light illuminated when the egr vacuum hose is disconnected? Sure I once read eu3 M47's can bypass the egr without issue, whereas the eu4 variant trips the engine management light when the same hose is unplugged.

Some simple yet effective maintenance I did which reduced black smoke for my eu4 M47are as follows:

Replace egr thermostat, replace cooling system thermostat, clean egr, clean intake manifold. 

The intercooler pipes can be unclipped and reinserted easily, gives an opportunity for close visual inspection - easy to access pipes etc if you lift out the fan and shroud first, which is really simple.

Edited by B.Merr
typo

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DJSteve   

thanks for the reply folks, yes im aware the egr bypass is a mot fail but i also know that mot is visual only therefore i will be making it look like egr is connected if not replaced egr by than (mot is not due till may)

their is no check engine light although an egr code is logged (joys of INPA), i intend to get eu3 injector refurbed/replaced when money allows, presently with egr unplugged and single eu4 injector car seems to be performing mostly ok bar very light smoke under WOT and cold running.

i will be changing the thermostats also as going off my driving today at least one needs doing as temps were dropping during motorway driving almost back into the blue area of temp gauge due to how cold it is today.

cheers on the info on intercooler pipes - how do you detach them. car has no fan shroud etc fitted anyway so no issue their with space

Edited by DJSteve

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