Starts fine, misfire cold, then fine - ideas?

[bherlingo]

Hello,
A lengthy explanation follows! I have a Berlingo with DW8 1.9 Diesel in it. Starts immediately and no prob, tickover perfect - but if I raise the revs slightly it misfires and black smokes. Back to tickover, perfect. After approx 3 minutes it runs perfectly without a hitch. When I was at the front of it today it was ticking over warming up and I detected a slight change in the engine note, possibly it was not the engine but a change in where the air was being drawn in - I knew it was going to be the transition from this odd running to perfect and it was. Does the engine draw in differently when cold? Its as if it has enough air to run on tickover and deprived if i rev it (hence the black smoke etc) until warmed when another air source opens. Within the air trunking I notice a black box affair in the centre front of the engine to the left of the air filter housing. It tee's off the air intake - what is this please and could it be contributing to this problem?
All help appreciated - ps its a 2004

[divingscubaboy]

Well theres a few options I would look at:
1 - EGR fault. I haven't studied the system that closely although I have the same engine as yours. I'll investigate a little more. We refer to EGR systems as soot collectors at work. Would you want to breath a load of secondhand dirty air? No! neither does an engine!
2 - Cold start fuelling device on the injection pump, although mine has the simple coolant operated thermostat and cable arrangement. I think 2 different types of injection pump are fitted
3 - Have you checked the air filter recently? I know this wouldn't make it run particularly differently between cold and hot but could be a contributing factor especially if the EGR valve is having a tantrum.
4 - I think the black box teeing off is just a resonator.

[bherlingo]

I would suggest it could be an EGR fault. I haven't studied the system that closely although I have the same engine as yours. I'll investigate a little more. We refer to EGR systems as soot collectors at work. Would you want to breath a load of secondhand dirty air? No! neither does an engine!

Thanks - Nope, can't say I would but often have to emerging from shopping centres and the likes these days! Only place the smokers seem to congregate...
Would the EGR consistently not work correctly when cold but work perfect when warm (well, thats an exaggeration - not warm but run for 3 minutes on tickover). Does it work by deflecting the airflow for a period? If so, it fits the bill..

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2 - Cold start fuelling device on the injection pump, although mine has the simple coolant operated thermostat and cable arrangement. I think 2 different types of injection pump are fitted

In case this is relevant - all this was working perfectly until the engine blew a head gasket (big time...properly cooked)- the engine was swapped but retained the fuel pump - it all started from this point.

[divingscubaboy]

Not sure of the exact operation on the Bingo, but operation normally temperature related.

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In case this is relevant - all this was working perfectly until the engine blew a head gasket (big time...properly cooked)- the engine was swapped but retained the fuel pump - it all started from this point.

The above puts a slightly different slant on it, adds a few more dolly mixtures to the liquorice allsorts!
Do you know the history of the 'new' engine? who fitted the pump to the engine? Could be a case of incorrect pump timing. Black smoking can be a sign of the pump being retarded / insufficient fuel supply.

[bherlingo]

Not sure of the exact operation on the Bingo, but operation normally temperature related.

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In case this is relevant - all this was working perfectly until the engine blew a head gasket (big time...properly cooked)- the engine was swapped but retained the fuel pump - it all started from this point.

The above puts a slightly different slant on it, adds a few more dolly mixtures to the liquorice allsorts!
Do you know the history of the 'new' engine? who fitted the pump to the engine? Could be a case of incorrect pump timing. Black smoking can be a sign of the pump being retarded / insufficient fuel supply.

Agreed, a mechanic installed it though. Is it possible it could be a timing issue if it only does it for 3 minutes and then runs perfect though? I would have thought it would do it all the time - and it ticks over lovely too. It really seems to be air starvation of some sort but I suppose overfueling amounts to the same thing so...? In the absence of any more ideas I could take it in somewhere different and have that checked

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[quote='divingscubaboy' pid='10038' dateline='1316119567']

Do you know the history of the 'new' engine? who fitted the pump to the engine? Could be a case of incorrect pump timing. Black smoking can be a sign of the pump being retarded / insufficient fuel supply.

The procedure followed was;
before removing timing belt the cam was locked with 13mm bolt, crank pinned and fuel pump locked. Replacement engine arrived locked by cam and crank but pumpless - old pump fitted in locked position and new Dayco cam belt kit fitted.

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Black smoke only during the 3 minute warm up (if you try to rev it) then none at all after that and none if you leave it to tickover at any point

[divingscubaboy]

With regards to the timing you have a point but again can be temp / speed dependent in the rev range. I don't think the bingo is complicated enough but some engines have a thermo element to control advance / retard for emissions. I wouldn't expect it to be overfuelling otherwise it would be white smoke and you'd smell neat fuel. Are you using the injectors from your old engine?

[bherlingo]

With regards to the timing you have a point but again can be temp / speed dependent in the rev range. I don't think the bingo is complicated enough but some engines have a thermo element to control advance / retard for emissions. I wouldn't expect it to be overfuelling otherwise it would be white smoke and you'd smell neat fuel. Are you using the injectors from your old engine?

No, the injectors are from the new engine and are unproven. The new engine allegedly had done 51k - but I have no proof of that. Again I wonder if the injectors could have that effect for just 3 minutes and work perfect on tickover and then on normal running - it would need to be all of them too. The key is the temp difference, if you turn the engine off you have to leave it to cool completely before it would do this again.

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I just did a little experiment and here's what happens - I went out and started it, problem there. I went to the front grille whilst it was ticking over and waited for the 3 or so minutes with my head by the grille. There was a definite note change in the airbox area at the 3 or so minutes and I tried the engine and it ran perfect again. Is this normal (the noise change not the resultant problem of course)
What is it that makes the change, its definitely not the engine tone

[divingscubaboy]

I'll check mine and get back to you. That does sound very much like EGR as you say its not an engine note change but related to the airbox etc.

[bherlingo]

I'll check mine and get back to you. That does sound very much like EGR as you say its not an engine note change but related to the airbox etc.

Thanks - That would be great if you could.
Regards
Ian

[bherlingo]

Well the issue is definitely EGR valve - I took the air intake connected to the EGR off and noted the position of the butterfly flap. It was open until I started it up whereupon it immediately closed. On tickover as above, it was happy - clearly getting enough air for the low revs - then when revving it falters. I held the flap open with a screwdriver and it immediately ran fine. I've disconnected a vacuum pipe running to it and it now stays open, and runs fine. My guess is that one of these vacuum tubes is connected wrong in the engine change - I need to get a look at another DW8 setup to check/correct it, I doubt a manual would show the layout fully.