White smoke on start up
Discussion
Hi all... ok so this is driving me mad. just cant get to the bottom of it...
i have a navara pickup with a 2.7 terrano tdi in it.
on cold start it bellows out white smoke, runs rough, then stalls. i can rev through it with a bit of throttle (to avoid stalling) but the strange thing is, after that the engine runs, pulls and starts just fine, until the next day.
at first it was intermittent, now its every morning. changing the fuel filter cured it for a few weeks. now its back and worse than ever.
glow plugs work perfectly.
heres a vid of it: http://cloud.cliffdesign.co.uk/cE9B
my hunch is air or water... any thoughts?
i have a navara pickup with a 2.7 terrano tdi in it.
on cold start it bellows out white smoke, runs rough, then stalls. i can rev through it with a bit of throttle (to avoid stalling) but the strange thing is, after that the engine runs, pulls and starts just fine, until the next day.
at first it was intermittent, now its every morning. changing the fuel filter cured it for a few weeks. now its back and worse than ever.
glow plugs work perfectly.
heres a vid of it: http://cloud.cliffdesign.co.uk/cE9B
my hunch is air or water... any thoughts?
In that case it is pretty much confirmed that you have leaky injectors, so the fuel pressure remaining in the fuel lines is leaking down into the combustion chamber/s when the engine is turned off.
EDIT.
The only other thing I could think of is if it has a cold start jet & this could be flooding the engine with fuel on start-up.
EDIT.
The only other thing I could think of is if it has a cold start jet & this could be flooding the engine with fuel on start-up.
Edited by andyiley on Friday 14th August 12:58
Generally I think diesel injectors can be refurbished, try googling local places that may do this.
The last set I had done (admittedly they were petrol C/R injectors) cost around £100 for 6 to be done.
Probably worth doing anyway.
Don't see how it could be the pump, as if the injectors were ok how would the pump pump diesel past the injectors?
The last set I had done (admittedly they were petrol C/R injectors) cost around £100 for 6 to be done.
Probably worth doing anyway.
Don't see how it could be the pump, as if the injectors were ok how would the pump pump diesel past the injectors?
For a diesel, the start is the hard bit!
Because compression ignition engines rely on the heat of compression to initiate combustion, they can be quite picky about starting!
The "heat" bit comes from the compression, so leaky rings, slow cranking or incorrect valve timing all can reduce that bit
The "fuel" bit requires nicely atomised fuel in the correct quantities. Large droplets of fuel, caused by low rail pressure at start or worn injector nozzles, are difficult to heat up, and tend to stick to the cold walls of the cylinder. And worse, if the cylinder fails to fire on the first few turns, the injector keeps on pumping in more fuel, which cools the cylinder even more, making it even less likely to fire! And when it does, all the liquid diesel gets chucked out into the exhaust and burnt at low pressure and temperaure, effectively creating a smoke screen out back!
So, here are the test you need to do BEFORE you spend any money changing stuff:
1) Check glow plugs - done!
2) Check it cranks at a decent speed (no knackered battery or stater motor)
3) Do a cold cranking compression test
4) Log, ideally using an OBD tool, the fuel rail pressure prior to, during, and after a start event. You could also use a multimeter to read the pressure sensor output, but it's not ideal, as you want to see pressure vs engine speed. (worn HP pumps are less efective at low speed, leading to low rail pressures at cranking)
5) If that all looks normal, out with the injectors and get them tested and re-conditioned
Most people, just throw a new set of injectors at the problem BEFORE they work out what is actually wrong with it, It could be as simple as a failing rail pressure sensor or lift pump.......
Because compression ignition engines rely on the heat of compression to initiate combustion, they can be quite picky about starting!
The "heat" bit comes from the compression, so leaky rings, slow cranking or incorrect valve timing all can reduce that bit
The "fuel" bit requires nicely atomised fuel in the correct quantities. Large droplets of fuel, caused by low rail pressure at start or worn injector nozzles, are difficult to heat up, and tend to stick to the cold walls of the cylinder. And worse, if the cylinder fails to fire on the first few turns, the injector keeps on pumping in more fuel, which cools the cylinder even more, making it even less likely to fire! And when it does, all the liquid diesel gets chucked out into the exhaust and burnt at low pressure and temperaure, effectively creating a smoke screen out back!
So, here are the test you need to do BEFORE you spend any money changing stuff:
1) Check glow plugs - done!
2) Check it cranks at a decent speed (no knackered battery or stater motor)
3) Do a cold cranking compression test
4) Log, ideally using an OBD tool, the fuel rail pressure prior to, during, and after a start event. You could also use a multimeter to read the pressure sensor output, but it's not ideal, as you want to see pressure vs engine speed. (worn HP pumps are less efective at low speed, leading to low rail pressures at cranking)
5) If that all looks normal, out with the injectors and get them tested and re-conditioned
Most people, just throw a new set of injectors at the problem BEFORE they work out what is actually wrong with it, It could be as simple as a failing rail pressure sensor or lift pump.......
Max_Torque said:
1) Check glow plugs - done!
2) Check it cranks at a decent speed (no knackered battery or stater motor)
3) Do a cold cranking compression test
4) Log, ideally using an OBD tool, the fuel rail pressure prior to, during, and after a start event. You could also use a multimeter to read the pressure sensor output, but it's not ideal, as you want to see pressure vs engine speed. (worn HP pumps are less efective at low speed, leading to low rail pressures at cranking)
5) If that all looks normal, out with the injectors and get them tested and re-conditioned
Great help thanks, but I'm not equipped well enough to investigate 2, and 3 at home :-/2) Check it cranks at a decent speed (no knackered battery or stater motor)
3) Do a cold cranking compression test
4) Log, ideally using an OBD tool, the fuel rail pressure prior to, during, and after a start event. You could also use a multimeter to read the pressure sensor output, but it's not ideal, as you want to see pressure vs engine speed. (worn HP pumps are less efective at low speed, leading to low rail pressures at cranking)
5) If that all looks normal, out with the injectors and get them tested and re-conditioned
And it's not a common rail so 4 is irrelevant...?
And a friend of mine fixed a similar problem with a new alternator. The crank speed was just slow enough to cause a problem, although barely noticeable with the ear/eye.
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