EGR valve problem?

[john.errington]

It happened again!  About a year ago I started this thread

 

http://www.briskoda.net/forums/topic/248027-misfire-and-black-smoke-on-diesel-19tdi-at-140k-miles/?hl=egr+valve#entry2948130

 

"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."

 

Well, it happened again. Only getting 30mpg - on a diesel!

 

So I took it back to the garage and they put it on the diagnostics.  No fault showed.

 

and they cleaned the EGR valve.  £40  Ran better but didnt cure problem

 

Back to the garage and the tech discovered bad readings from the MAF. SO they replaced it. £140 Ran better but didnt cure problem

 

Could it be the turbo?  2 bottles Forte Turbo cleaner in the tank £30.  I can hear the improvement in the turbo. .. - but didnt cure problem.

 

Looking back at my last thread I disconnected the egr vacuum pipe.

 

AND THE PROBLEM - - black smoke, hiccups, no accel - has gone!  MPG now 50 on a run.  Getting to 70mph  no bother  (and beyond! shh!).

Of course the engine warning light is now on.

 

So my question - do I have a faulty EGR, or is there something that controls the vacuum feed to the egr that could be faulty?  Or is the engine management system seeing the "fault" and doing something different?

Edited 28 July, 2013 by john.errington

[k.young]

If your car is out of warranty, get a Darkside Developements EGR delete kit and be done with it !!!    You won't look back.  You can get the fault light mapped out and also "at present" it will not cause you a problem at MOT because they only do a smoke test.

 

EGR's are the work of the devil !!!!!

[john.errington]

Yeah OK £75 + etcs well spent - then £400 for a remap?

I can get  new EGR for £50 ebay! All I'm asking is -is it the EGR that fails, or could it be ..  the solenoid valve?   .. or something else??

I dont want ot go ON replacing parts!

[mabautouk140]

hi yes there is a egr vacum control valve that the ecu controls and then the level of vacum aplied to the egr valve dertimines the level of egr if your disconecting the vacum line it would apear that it is being held open for some reason poss failure of the egr vacum valve allowing vacum to reach the egr valve holding it open when it isnt required by the ecu and as you have said the garage that looked at it found incorect maf values i would exspect what they where seeing was the fact egr is open reducing the amount of air passing the maf causing the reading to be lower than expected do you have acess to vag com or any diag software that you can check some readings if so with egr off at idle you should have aprox 450 reading on maf and when egr opens at idle you should see it change aprox by half some where around 250 is ok hope this helps

[john.errington]

Disconnected the EGR and it worked fine for two weeks. New EGR valve and BINGO! problem solved...

 

NOT!

The old EGR  was quite dirty and the exhaust gas inlet was sooty - even though it had recently been cleaned.

 

A few longish trips later and --its doing it again!.  Intermittently.

 

Ok we've eliminated the EGR as the fault. Now the turn of the vacuum system.  My reasoning - low pressure opens the EGR. Sticking open could be caused by

1: the solenoid valve not workng properly

2: problem with whatever allows air back into the EGR so it can close.

 

FOr my readers - £470 for an EGR delete kit is looking really good value!

[mabautouk140]

I would be looking at the vacuum valve in that case

[cheshire_cat]

I guess you have EDC 16 or newer as you have a fault light,    15 would log but not light the lamp--   with 15 maf readings would vary on a regular basis as the computer will open and close the egr --from memory every 2 minutes I would guess the more modern 1.9's also use a similar cycle----------as a last resort you could try putting a restrictor in the vac line if you don't find any other fault  somewhere,  in the region of .2-.3mm hole should be about right  and it is reversible if there's no joy 

[k.young]

Disconnected the EGR and it worked fine for two weeks. New EGR valve and BINGO! problem solved...

 

NOT!

The old EGR  was quite dirty and the exhaust gas inlet was sooty - even though it had recently been cleaned.

 

A few longish trips later and --its doing it again!.  Intermittently.

 

Ok we've eliminated the EGR as the fault. Now the turn of the vacuum system.  My reasoning - low pressure opens the EGR. Sticking open could be caused by

1: the solenoid valve not workng properly

2: problem with whatever allows air back into the EGR so it can close.

 

FOr my readers - £470 for an EGR delete kit is looking really good value!

You don't have to map it at all if you don't want to (if you don't mind staring at an Orange light) also a map doesn't have to cost £400.

Also, if you do map it, you will wonder why you never done it sooner!!!!!

[k.young]

If you are getting work done in that area, make sure you take the opportunity to give the inlet manifold a good spring clean.

[flat-eric]

Driving with the EML on is all good and well but the egr system is linked to regeneration of dpf and can throw all sorts of faults up if removed.

I bit the bullet and went to the guys at Shark and ditched the lot!

[k.young]

Sorry, mine's a BKD, so no DPF to worry about. I got the Darkside EGR delete, removed the EGR cooler and knocked the CAT out for good measure.

Tapatalk'd from my HTC SXE

[john.errington]

Now at Pulman VW who believe the fault is in the EGR cooler. I didnt even know it had one! Apparently they can get blocked.

[k.young]

My cooler was leaking coolant. Just another thing to go wrong, get rid of it (€400 part if it needs replacing)

Tapatalk'd from my HTC SXE

[cheshire_cat]

they can leak  (coolant) especially the early ones,   but blocked I doubt it   will be watching this space :-)

[cheshire_cat]

bump

[john.errington]

Took the plunge, had egr mapped out & eco+ remap. 5000 miles, never a problem, good economy and goes like stink! money well spent.