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PETER G
03-03-2009, 08:56 PM
Any one point me in the right direction, what effect would a faulty EGR valve have?

And would this show up in VAG-COM?

Are there any tests that can be done to check the EGR valve operation.

at idle with the engine warm (90 deg)
861 rpm
maf actual reading 460 mg/r
EGR duty cycle 4.8%

When the engine is reved up the readings appear more normal.

martin1810
03-03-2009, 11:10 PM
Have you taken the valve off and cleaned it ? You really need to see if the flap is opening and closing. If it jams closed you don't usually get a great difference in performance but if it jams open it can run rough at low revs/tick over.

Crasher
03-03-2009, 11:14 PM
It usually shows up as a fault code. What is the issue?

PETER G
04-03-2009, 08:53 AM
It usually shows up as a fault code. What is the issue?

low miles per gallon, I had the car re-mapped & on motorway runs was getting upto 55 mpg, now only getting 42, I have replaced the coolant temp sensor & the mass air flow sensor (the mass air flow sensor was bought from German, Swedish & French) I now realise aftermarket parts are of inferior quality, but before I go out & buy a genuine VAG MAF, I would like to be sure that is the problem & not something else.
Any input would be greatly appreciated.

:beerchug:

Crasher
04-03-2009, 11:56 AM
The EGR valve can be a problem so removing and clean is a good idea but a disgusting job.

PETER G
04-03-2009, 01:05 PM
The EGR valve can be a problem so removing and clean is a good idea but a disgusting job.


Why is it disgusting, what sort of crud is inside it????

martin1810
04-03-2009, 01:11 PM
It's just thick oily carbon gunk. Quite hard to remove and makes your hands filthy for weeks.
From a DIY point it is worth doing from a mechanic earning money perspective, it's not worth doing. I would do it because a bit of hard work costs nothing.

PETER G
04-03-2009, 01:16 PM
It's just thick oily carbon gunk. Quite hard to remove and makes your hands filthy for weeks.
From a DIY point it is worth doing from a mechanic earning money perspective, it's not worth doing. I would do it because a bit of hard work costs nothing.


What cleaning agent would you recomend????
I have a IPA aerosol.

passat 130 tdi
04-03-2009, 01:42 PM
i used white spirit on mine , a wire brush attatchment in a 18v drill and give it a good clean , you may want to remove the inlet manifold too and clean it. i saw good results after, no start up smoke and foul fumes , better running too.

Crasher
04-03-2009, 02:24 PM
I would compare it to liquid road tar. I use neat alkaline truck wash and a nylon bore brush. A wire brush would mar the internal bore and could cause the anti shudder flap to stick closed.

PETER G
05-03-2009, 11:09 AM
I would compare it to liquid road tar. I use neat alkaline truck wash and a nylon bore brush. A wire brush would mar the internal bore and could cause the anti shudder flap to stick closed.

Hi M8,
Just a quick question, what sort of diameter brush do I need????

Crasher
05-03-2009, 11:33 AM
I bought a pack with about five in and a quite big diameter one, say 20-mm, would be ideal.

passat 130 tdi
05-03-2009, 07:24 PM
be wary of any bristles getting stuck in the anti shudder flap , jamming it closed. :biglaugh:

the diver
05-03-2009, 08:59 PM
hi there. have recently had the same problem on my a4 tdi. the egrs have a tendency to partially leak- according to audi mech. mine,though was saturated in oil and gunk etc. my initial problem was also low mpg. i changed the egr but no difference. what did help though was unclogging the fuel cooler-this is attached to the fuel supply pipe (has a flow and return). it seemed to be restricting the flow of fuel- car felt as if it had turbo lag, hence using more fuel to compensate- overworking.a sign of this is smokey fumes when starting car cold- in morning especially. hope this helps. if you manage to solve the problem please let me know cause i think mine still isnt 100% though a lot better! sorry about long message not good at condensing messages!

Rolo
05-03-2009, 10:10 PM
Is this on top of the fuel filter? How did you clean it?

PETER G
06-03-2009, 06:33 PM
hi there. have recently had the same problem on my a4 tdi. the egrs have a tendency to partially leak- according to audi mech. mine,though was saturated in oil and gunk etc. my initial problem was also low mpg. i changed the egr but no difference. what did help though was unclogging the fuel cooler-this is attached to the fuel supply pipe (has a flow and return). it seemed to be restricting the flow of fuel- car felt as if it had turbo lag, hence using more fuel to compensate- overworking.a sign of this is smokey fumes when starting car cold- in morning especially. hope this helps. if you manage to solve the problem please let me know cause i think mine still isnt 100% though a lot better! sorry about long message not good at condensing messages!


according to the Haynes manual I have, fuel coolers where only used on engines manufactured up to 2002, not sure if this includes 2002, but anyway mine is end of 2003. Do these dates fit in with the age of your car??????

Crasher
06-03-2009, 06:57 PM
Fuel coolers were fitted to all PD’s, early ones had a water to fuel based system with a separate little radiator behind a grill on the right with the exchanger on top of thee fuel filter. Later cars had an air to fuel system with a grilled radiator running along the right hand floor of the car.

minty0_10
06-03-2009, 08:43 PM
hi there. have recently had the same problem on my a4 tdi. the egrs have a tendency to partially leak- according to audi mech. mine,though was saturated in oil and gunk etc. my initial problem was also low mpg. i changed the egr but no difference. what did help though was unclogging the fuel cooler-this is attached to the fuel supply pipe (has a flow and return). it seemed to be restricting the flow of fuel- car felt as if it had turbo lag, hence using more fuel to compensate- overworking.a sign of this is smokey fumes when starting car cold- in morning especially. hope this helps. if you manage to solve the problem please let me know cause i think mine still isnt 100% though a lot better! sorry about long message not good at condensing messages!

that sounds spot on the way my car is, id there anywhere were i can see some photos of where it is and what it looks like.
is the egr valve the silver thing with the rubber cap on towards the back of the engine bay

PETER G
09-03-2009, 07:25 PM
that sounds spot on the way my car is, id there anywhere were i can see some photos of where it is and what it looks like.
is the egr valve the silver thing with the rubber cap on towards the back of the engine bay


Anyone got pictures of the fuel cooler & where to find it & how to clean it. Also the EGR valve looks a bit tricky to remove, is it worth the effort to remove & clean it??

the diver
09-03-2009, 10:16 PM
hi there,
please not that my car is an audi a4 tdi. i know i posted to a vw passat thread but thought i could shine some light on the issue as i had the same problem, giving that the cars are very similar in mechanical and component terms.
sorry i have no photos i am only getting home after dark these nights plus my wife hogs the car! if i get the chance soon i will take some an forward on. yes the egr valve is the silver component with the black cap towards the back of the engine bay. the best i can do at the moment is describe where the fuel cooler is-- at the back of the engine bay ( bulkhead) half way across. it is beside the coolant temp sensor at the bottom of the engine. it is attached to the fuel line which runs from the pump (pump is located underneath the rear right hand seat).to clean it, the fuel line pipe needs to be removed. air needs to be blown to clear out any blockages in the fuel line. then blow out any blockages in the fuel cooler. the requires an airline with a compressor-- but not too much pressure req! i am fortunate that my mate is an audi technician who came to help me do this!
:beerchug: