"misfire" and black smoke on diesel 1.9TDi at 140k miles

[john.errington]

For some time now my Octy has had a slight intermittent "hiccup" in low gears at around 2000 rpm. Only occasional but sometimes quite sharp.

Recently there have been three or four occasions when it would not accelerate above 2k rpm.

It also seems more prone to stalling.

Today coming up a steep hill I noticed this happened in second gear, and when I floored the throttle i saw a cloud of black smoke.

I eased off and when the hill levelled out I was able to accelerate away.

I've had the turbo cleaned out and given it some injector cleaner, but no better.

Can anyone shed any light on a probable cause? My feeling is that 2k is where the turbo cuts in so that could perhaps be significant.

[andyvee]

Not accelerating above 2k is limp mode - get it scanned for a fault code, but it sounds like a turbo on its way out to me

[john.errington]

Thanks Andy - no fault indication, no faults reported on diagnostics. and I dont think its limp mode - I didnt need to turn the ignition off to reset it, it just purred away when I let up on the throttle and it came to a less steep bit.

[andyvee]

Not limp mode then.

Have you checked the turbo pipework for leaks?

[john.errington]

No Andy. I must admit the vacuum system is a mystery to me. However I've got a diagram I'll check it tomorrow.

In the documentation it says if the turbo control system doesnt move smoothly it can cause jerkiness at "changeover". I'm not looking forward to forking out for a new turbo!

[john.errington]

I checked the vacuum connections etc could not find anything wrong. Chucked it at our local garage and they found nowt on diagnostics (except for no 4 glow plug)

Strip and decoke EGR

replace glow plug

all in inc diagnostic £97.54

Does seem better but we'll see.

Edited 31 August, 2012 by john.errington

[cheshire_cat]

my money would be on the egr and manifold coked

[Lofty79]

if they had to decoke egr, the inlet manifold will be the same. youll need to do this aswell

[john.errington]

oh bu**er! seems OK for now, can I do the manifold or is it another garage job?

[Lofty79]

anyone can do a manifold. 8 bolts (probably) Hex key heads (most likely). Connected to back of engine at the head, next thing along from egr valve - simple.

Edited 2 September, 2012 by Lofty79

[john.errington]

Thanks Lofty: can you tell me - the egr valve has moving parts that can stick causing problems. However the manifold has no moving parts - so why does it need decoking?

I looked EGR up on wiki, it says:

By feeding the lower oxygen exhaust gas into the intake, diesel EGR systems lower combustion temperature, reducing emissions of NOx. This makes combustion less efficient, compromising economy and power. The normally "dry" intake system of a diesel engine is now subject to fouling from soot, unburned fuel and oil in the EGR bleed, which has little effect on airflow but can cause problems with components such as swirl flaps, where fitted. Diesel EGR also increases soot production, though this was masked in the US by the simultaneous introduction of diesel particulate filters.^[6] EGR systems can also add abrasive contaminants and increase engine oil acidity, which in turn can reduce engine longevity.^[7]

So I'm guessing the EGR valve was sticking open.

My car (1.9 BXE/JCR) has done 135k miles - would it be sensible for me to do the conversion that removes the EGR valve?

[Lofty79]

May not be so necessary then if its running fine now. If you plead on the forum you may be able to pay someone to map out the egr from ecu. As the age of your car means the computer is a bit wise to deletes. A map out would disable it and that's all it would need.

[john.errington]

Thanks Lofty: went on holiday - car fine. got 100 miles - first "comfort" stop - and on pulling away - black smoke cough cough. Good job I had read up another egr question - did what it advised and pulled the vacuum tube off the egr and plugged the end.

3 weeks later - running fine - but of course engine warning light on.

On balance I think I'll try to get it mapped out. Plead coming up! And maybe I'll get the manifold decoked too next time it needs work.

[TDIum]

I had problems with the EGR on my Pug 406 HDi. No garage or dealer I tried was willing or able to correctly diagnose the sticking EGR butterfly valve.

Once I'd worked out what was going on (I'm an engineer but in electronic systems, not mechanical) it was easy to disconnect the vaccum pipe from the solenoid to the EGR valve, and block up the pipe. Ran sweet as a nut after that.

[Stuart_J]

Might be of interest http://www.allardaluminiumproducts.co.uk/air-systems/egr-delete-kits.html

[andyvee]

Personally, I would recommend this one

http://www.darksidedevelopments.co.uk/products/darkside-1-9-8v-pd105-2-0-16v-tdi-pd-ppd-and-cr-egr-delete-race-pipe.html

[john.errington]

I'm not convinced the egr valve provides a serious enough obstruction for these replacements to make much difference. And the egr still needs mapping out.

However for anyone thinking of getting theirs cleaned - take my advice - just fit a delete tube instead!

[Booble]

my current car cdti vectra is having similar issues, but its going next week as part ex for a new octy vrs.

Here's a dumb question, if simply deleting sorts issue with no side effect, what's the point of egr in first place? What benefit does does it add?

Seems about as useful as an appendix.

[andyvee]

Emissions related.

[andyvee]

I'm not convinced the egr valve provides a serious enough obstruction for these replacements to make much difference. And the egr still needs mapping out.

However for anyone thinking of getting theirs cleaned - take my advice - just fit a delete tube instead!

The problem is they can get very tarred up - I have seen some where it has narrowed the bore a fair bit. As you say, get it mapped out and replace with a delete tube - it can't clog up again then.

[Booble]

Emissions related.

so deleting it would have no effect on MOT regarding emissions?

thanks

[andyvee]

Nope - others have passed MoT's fine with EGR deletes done.

Have a look here

http://en.wikipedia.org/wiki/Exhaust_gas_recirculation

[Booble]

thanks Andy, something to bear in mind for future.

[derek666]

mine has now got the same symptoms , 1.9tdi bxe engine 200,000 plus miles lol

 

low revs, it coughs a little bit, but after coughs, out comes the smoke !

 

ive jusr replaced egr valve, thinknig it could be that, but still the same.

 

anyone with any other suggestions ?

 

 

cheers

Edited 6 October, 2015 by derek666

[derek666]

Little update Incase anyone else has the same issues,

I've now unplugged the mass air flow, and it now drives the way it should !

I've not purchased a new one yet, but is on order.

Just need to fix the temperamental engine knocking noise now lol