V6 CDTI sometimes hard to start

[Celes]

My V6 has developed funny symptoms lately. It sometimes takes a while to start from cold What baffles me is that it can also happen, although not as bad, when the engine temperature is around the 80°C mark

Overall performance is good, mpg is good, but it does smoke quite a lot (grey and black). It sometimes judders under acceleration below 2000rpm but not much. It's had a service 2 months ago and only done 6k miles since.

The spanner light comes on, but only shows a cruise control fault. Never been in limp mode.

[mattv6diesel]

maybe the suction part isn't working properly. the part instead of the pump in the fuel tank. might be best getting a dealer to look so they can see the fuel pressure on cranking

[Celes]

So you think I have a weak low pressure fuel pump?

[m8internet]

Just to confirm
The engine suffers VERY poor starting on cold, but is fine when warm or hot?

When warm and idle, the exhaust gas is clear
When you rev the engine (as you would do for an emission test) how much BLACK smoke is produced?
Once the engine has returned back to idle, is the exhaust gas still clear?

Under heavy load / high revs does the exhaust produce smoke?
On changing gear does the exhaust produce smoke?
[For the above it might be best to get someone to drive behind and take a video, and you can then check]

[Celes]

Just to confirm
The engine suffers VERY poor starting on cold, but is fine when warm or hot?

When warm and idle, the exhaust gas is clear
When you rev the engine (as you would do for an emission test) how much BLACK smoke is produced?
Once the engine has returned back to idle, is the exhaust gas still clear?

Under heavy load / high revs does the exhaust produce smoke?
On changing gear does the exhaust produce smoke?
[For the above it might be best to get someone to drive behind and take a video, and you can then check]

-The engine only sometimes suffers poor starting on cold and is usually fine when warm or hot
-when warm and idle, there is no visible smoke from the exhaust (ie. clear fumes)
-When I rev the engine there is quite a lot of black smoke, but only after the first boost. It's fine (no smoke) if after booting it I hold the revs at 4000
-Exhaust still clear when back to idle
-Under heavy load there is some grey smoke which is barely noticable (+black if I've driven slow for a while)
-On changing gear there is no smoke coming out of the back, only when I floor it, it puffs out greyish and a bit black smoke


Clear enough?

[m8internet]

What is the current mileage, and date and mileage of last service

How old are the glowplugs, date and mileage last changed?
How old is the camshaft sensor, date and mileage last changed?
Have the injector nozzles been replaced, if so were the new, used, or refurbs?

The black smoke may be due to too much fuel being fed to the fuel pump
The grey smoke suggests there is something other than diesel in the fuel tank

[Big Sig]

-The engine only sometimes suffers poor starting on cold and is usually fine when warm or hot
-when warm and idle, there is no visible smoke from the exhaust (ie. clear fumes)
-When I rev the engine there is quite a lot of black smoke, but only after the first boost. It's fine (no smoke) if after booting it I hold the revs at 4000
-Exhaust still clear when back to idle
-Under heavy load there is some grey smoke which is barely noticable (+black if I've driven slow for a while)
-On changing gear there is no smoke coming out of the back, only when I floor it, it puffs out greyish and a bit black smoke


Clear enough?

Thats exactly like mine was - although I never had a starting problem. If you rev it you will get some black smoke as it struggles to burn all the fuel correctly.

[Penfold101]

I can confirm he puts out smoke under acceleration. He wasn't impressed when he saw that mine didn't...

[m8internet]

If you rev it you will get some black smoke as it struggles to burn all the fuel correctly

The black smoke is due to the lack of pressure release valve on the EGR
As a result the valve to the EGR stays open on a rapid increase in revs

Most other engine manufacturers get round this by having a longer pipe between the turbo and EGR
However, this results in greater heat and the pipe often fails
Personally, I would rather not have the pipe as Isuzu have done with the extra black smoke

[Celes]

What is the current mileage, and date and mileage of last service

How old are the glowplugs, date and mileage last changed?
How old is the camshaft sensor, date and mileage last changed?
Have the injector nozzles been replaced, if so were the new, used, or refurbs?

The black smoke may be due to too much fuel being fed to the fuel pump
The grey smoke suggests there is something other than diesel in the fuel tank

-Actual mileage is unknown, the clock shows 107.5k miles, OP-COM says 123k. Last service (oil, oil filter, air filter, fuel filter) was done on the 22nd of March at exactly 102k miles (clocks). The engine does not use oil or coolant.

-From what I know, but I didn't check further, the glowplugs might be still original from 2003 when the car was made. Bad glowplugs wouldn't cause poor starting at more then 20°C and when the engine is warm. No fault codes for glow plugs or glow plug relay.
-Camshaft sensor as above. No fault codes for it either.
-Injectors are still original. The engine sometimes makes a ticking noise when going up hill in a high gear on low revs. My old 3.0 used to do it but it was a lot more dramatic and loud. That was cured when I replaced all 6 injectors, yet it still sometimes puffed out a bit of greyish smoke. It never had starting problems like my current V6.

On my last V6 I replaced: EGR, Injectors, SCVs, Turbo....AND IT STILL SMOKED WHEN REVING THE ENGINE HARD It never ran as good as my current 3.0