Problems when engine warm

[stidge]

Hi everybody,

2001 406 2.0 hdi 110. Starts and runs perfect when cold, however once up to temperature has no power, won’t rev past 2500-3000rpm, poors white smoke. Any ideas much appreciated

[steve_earwig]

White smoke could be steam (head gasket?) or diesel (stuck open injector)

[barbaren]

Headgasket or cracked cylinderhead.

[PeterN]

Are you loosing coolant? Is the cooling system pressurised excessively i.e blowing coolant from the overflow or filler cap? If you have either it would indicate the suggestions above.

That would normally cause the engine to run unevenly as at least one cylinder will be down on power. If its an injector fault that would usually cause the engine to 'knock'.

Peter

[stidge]

Doesn’t appear to be loosing coolant and doesn’t overheat. However, just opened expansion cap and copper residue is visable, I’m thinking k-seal or similar been chucked in.

[GingerMagic]

Could it be something less sinister, like a stuck EGR, or a blocked air filter..?
I'm not sure why it runs fine when cold but as soon as things warm up then you get problems...

If you add your location here, maybe someone local can use diagnostics on it to check the air flow, EGR, injection values etc.

Hopefully it's not the head gasket, worth exploring the cheaper options first

[barbaren]

Could it be something less sinister, like a stuck EGR, or a blocked air filter..?
I'm not sure why it runs fine when cold but as soon as things warm up then you get problems...

If you add your location here, maybe someone local can use diagnostics on it to check the air flow, EGR, injection values etc.

Hopefully it's not the head gasket, worth exploring the cheaper options first

The reason it runs smooth when cold, is because metal expanse when hot, which means the crack in the either the headgasket or the head itself, will open up, and allow water to flow.
If there is an inbalance on the fuel/airside of the engine. The smoke will be black.

[GingerMagic]

Fair enough

I thought white smoke could also be unburned fuel - which made me believe the air/fuel mixture was wrong..

As you can tell I'm not a mechanic

[barbaren]

You are kind of right.
White smoke can appear if the air/fuelmixture is off, but only at idle, as soon as power is applied the smoke will turn black.

[dirtydirtydiesel]

Whilst I agree with barbaren,

My head gasket was gone, I had no white smoke from the exhaust & my header tank was blowing out coolant when
warm, it also had a wobble on idle.

If the head is cracked it should pressurise the cooling system, the best thing to do is have a sniffer test done.

When the white smoke is coming out the exhaust, smell it. If it's got a sweet smell it's coolant,
or you might smell unburned diesel.
In which case it's an injector problem or you might have water in your fuel.

If you are positive that it's NOT pressurising the cooling system & not overheating you could just try
using all the diesel up then changing the fuel fillter, when you do this pour diesel injector cleaner into the filter housing.
Then go & put half a tank of diesel in from a quality source, ESSO, SHELL ect & put in a bottle of fuel system cleaner
in before you put in the fuel.

My favourite is Forte fuel system cleaner , they do two for you that can be combined
Advanced formula diesel treatment & Diesel specialist injection cleaner.

I would first have a sniffer test done, then if that is ok proceed with the above.
The two treatments will cost you £30 of eBay, a filter £10 & half a tank of diesel £45 -£50
If you go down this route, run your car till your fuel light is on (ignore the range)
Change the fuel filter ( half filling the housing with the injector cleaner)
Then start up & go put 35 liters of quality fuel in having put the rest of the injector cleaner & fuel system cleaner in first.

I am not saying this WILL fix your problem but if you have water in bad fuel or dirt in the system it will help & can't hurt.

I personally stay away from supermarket fuel, always use a well used petrol station & won't use it if the tanker has just been
It stirs up all the crap in the bottom of the fuel tanks!

Oh & my re-mapped 110 ( approx 150 bhp with supporting mods ) doesn't like to rev past 3k
It's sweet spot is 1500 to 3000, it pulls really hard through there.
It will go to 3.5k but stops dead at 4k.
A hdi tuning map will allow it to rev to 4.5k but at the expense of accelerated engine ware.
But not before you have made sure the engine is in tip top condition

[stidge]

Thanks for your input chaps, sorry late in replying, been busy.
After a little play around it turns out it was the maf sensor.

[GingerMagic]

That's a great result.

I know the MAF can get dirty and cause fueling issues but I've not known one to be that bad...!!

Did you buy a genuine one or an eBay special?

[PeterN]

I have had some of those symptoms caused by a faulty pressure regulator on the back of the HP diesel pump, rev limiting when hot and difficult to start, not noticed any smoke though. They are not to difficult to change, remove the fuel filter assy and you can get there quite easily, two screws, philips or torx and a plug.

You can get them secondhand on ebay for not to much money.

Peter

https://www.ebay.co.uk/sch/i.html?_from ... r&_sacat=0