HEAVY smoking Relay 2.2HDi

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Citroen Surf Bus
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HEAVY smoking Relay 2.2HDi

Post by Citroen Surf Bus »

Hi, mechanics - do these symptoms suggest a potential cause?
My 2003 turbo-diesel Relay has long had a habit of starting perfectly - then beginning to smoke and bog down after a minute or so. Driving under load always quickly cleared it, and it ran perfectly then.

However! Yesterday, it began to smoke VERY heavily soon after startup. Again, I managed to clear it - but now it's become almost permanent - I can drive maybe 20 secs before the heavy grey/black smoke and power loss kick in.

Over-fuelling? Any idea what might cause this...? A sensor failure maybe?

Ps. I've just blanked the EGR valve: no effect at all.
Peter.N.
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Re: HEAVY smoking Relay 2.2HDi

Post by Peter.N. »

You can't really over fuel a diesel as the fuel in is proportional to the power out, there is no throttle on the air. You can though have a restricted air supply which will cause that. Has the air filter been changed lately? . Black smoke will be a combustion issue, could be that the turbo is not producing boost initially. Does it smoke on tickover?

Peter
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Re: HEAVY smoking Relay 2.2HDi

Post by Citroen Surf Bus »

The air filter is overdue. Will take it out and see what happens.

Interesting point about overfuelling - I see what you're saying, although I've heard the word used before - including by mechanics.

It does smoke a little on tickover - once the 20 sec startup phase is over. MUCH worse on revving. (Full-on military smokescreen!)

I kindof assumed the turbo plays little role until it kicks-in at higher revs. Am I wrong?

Thanks very much for your assistance - I don't get live notifications, but will reply asap. ( :
Peter.N.
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Re: HEAVY smoking Relay 2.2HDi

Post by Peter.N. »

No you are quite right. What colour is the smoke at tickover?

Peter
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Re: HEAVY smoking Relay 2.2HDi

Post by Citroen Surf Bus »

At tickover - mid grey. Full throttle - black!
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GiveMeABreak
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Re: HEAVY smoking Relay 2.2HDi

Post by GiveMeABreak »

I suggest you put unblank your EGR for a start. Apart from not legal to do now, it will increase emissions. Then check you DPF. There should be no black smoke. There has been a recent case of a member discovering his DPF has been 'holed' and he now has to rectify it as it won't pass the MOT. That was causing thick smoke. But ultimately you need to get it diagnosed with a lexia.
Hell Razor5543
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Re: HEAVY smoking Relay 2.2HDi

Post by Hell Razor5543 »

Definitely change the air filter. It should improve things, including the smoke level and fuel economy. While there may be other things causing this problem a replacement filter is inexpensive and (normally) simple to replace.
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Re: HEAVY smoking Relay 2.2HDi

Post by Citroen Surf Bus »

Thanks for the responses folks.

Ok, I removed the air filter as an experiment - no effect. (I also blanked the EGR as an experiment - no effect)

My Relay is 2003 so no DP Filter, I'm guessing?

No obvious air leaks found on inlet side.

My thoughts are:

1. What's the solenoid controlled butterfly valve in the inlet manifold do? (Was told "diesels don't have a throttle") Could solenoid failure strangle airflow?

2. Does turbo oilseal failure fit with black smoke? Or would it be BLUE?
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GiveMeABreak
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Re: HEAVY smoking Relay 2.2HDi

Post by GiveMeABreak »

Best thing is to put your VIN up here and I can see exactly which engine and fittings you have.
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Re: HEAVY smoking Relay 2.2HDi

Post by Citroen Surf Bus »

Case solved, folks!

The butterfly valve on the inlet manifold (what is it for? Cold starts?) was being held shut by the solenoid valve. Disconnected it and bingo!

The long term problem of smoke shortly after starting, clearing when warmed is still there - but the horrendous grey and black heavy smoke/ total power loss has definitely gone.

Thanks to all responders who helped me work through the prob. ( :
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Re: HEAVY smoking Relay 2.2HDi

Post by markking »

On my DV6 Dispatch the intake valve is to reduce shut-off shake - it shuts on key-off to block the air supply to the engine - no air=no compression.
With the EGR working normally smoke will be increased as a result of the combustion chamber temperature being reduced - the EGR valve reduces NOx emissions by reducing the amount of oxygen available for combustion, thus lowering combustion temperature - a small percentage of the oxygen is replaced by exhaust gases (which play no part in the combustion process).
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Re: HEAVY smoking Relay 2.2HDi

Post by Citroen Surf Bus »

Thanks for that reply, only just seen it - 5 months late!!

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xantia_v6
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Re: HEAVY smoking Relay 2.2HDi

Post by xantia_v6 »

Citroen Surf Bus wrote:
31 Oct 2019, 22:07
Thanks for that reply, only just seen it - 5 months late!!

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Re: HEAVY smoking Relay 2.2HDi

Post by Citroen Surf Bus »

Hey, thanks!