Member Since: 02 Apr 2010
Location: Australia
Posts: 16
Did mine tonight, not as bad as some, but bad enough to make me cringe at the thought of how much gunk is lurking further down. Will definitely be investing in an EGR valve blanking kit soon. MY06 - 95,000km
Off on a 1,500km road trip on Saturday so will see if this makes any difference to fuel consumption.
Before
After
20th Oct 2011 3:27 pm
Stay Frosty
Member Since: 25 Jan 2010
Location: Merseyside
Posts: 82
Did mine today after reading this thread.
Cant get the picture to upload
EGRs getting blanks next week. Will update on MPG. Dropped from 35mpg to about 29 after getting the cam belt done. So keep to get back up there as it shoots £1 coins out of the exhaust at the mo.
30th Oct 2011 4:14 pm
Da1sycat
Member Since: 20 Nov 2011
Location: UK
Posts: 66
2005, 74k. COMPLETELY blocked with soot and oil. No warning lights on dash. 5 minute job to give it a wipe clean. Engine response noticibly crisper and mpg up by indicated 5mpg
Thanks to you Guys for yet another good fix!
13th Dec 2011 1:53 am
rich11235
Member Since: 19 Dec 2010
Location: Henfield, West Sussex
Posts: 22
Hello people,
I though I might try and add a bit of knowledge about what the MAP sensor does. As most of you know, its a pressure sensor, and would be better called the boost pressure sensor. The wiki article quoted early on in this (extensive) post is a little bit wrong for a diesel (although not far off for some kinds of petrol engine). The MAP on the TDV6 will be used to control the turbocharger vanes (basically to turn the turbo up and down). The ECU will have a target boost pressure, lets say 2.5bar (35psi) absolute. The sensor measures the current pressure (lets say its 1 bar) i.e. normal atmospheric pressure, the ECU will then say to the turbo "close the vanes and build up boost" until the target pressure is reached.
Any kind of severe crap in the sensor holes will limit the ability of the sensor to read the pressure, it will probably cause quite a lag in detection of the building up pressure, leading to lag or overshoot (effectively turbo lag).
The measured pressure doesn't directly influence the amount of fuel injected (not like on some petrol engines). But since the air flow (i.e. the A.F. in the name of the MAF sensor) is proportional to the boost pressure, too low a measured boost pressure will lead to too low a MAF reading under hard acceleration, which will cause the ECU to limit the injected fuel quantity (to keep black smoke under control) which will lead to sluggishness.
The crud you see is almost definitely caused by the EGR. SO blanked EGR systems shouldn't collect crud (unless the turbo oil seals are shot or oil is leaking into the air intake via the breather). But as already mentioned this usually results in just a coating of oil.
Fouling/clogging of EGR circuits (and the sticking of EGR valves and other components) is one of the single biggest warranty issues faced by diesel car manufacturers. Lots of research has been done on what makes EGR circuits clog up; current knowledge is best summarised by thinking of a golden (or black) triangle:
soot in exhaust
hydrocarbon/unburnt fuel in exhaust
low temperatures/cold surfaces
If you have any two out of those 3 in your EGR circuit, your going to get some crud. This explains why some people's crud is dry and crumbly, others is shiny and oily (more hydrocarbon).
Since diesel exhaust naturally contains soot under most operating conditions, you're never going to get away from that. The hydrocarbon kicks in when high levels of EGR are applied at light load in order to reduce emissions in a particular area. And the cold temps kick in when you do lots of light load driving.
Since the TDV6 was developed by Ford, I can almost guarantee it will have been though the infamous Ford "Granny Cycle" which repeatedly does the equivalent of Mrs Miggings trundling down to the village shop and back at 20mph, ad infinitum. But EGR clogging is fickle thing, and even an EGR system which passes that kind of abuse test might fail depending one act drivers style. Basically, like many problems, it can be helped by giving it a good thrash every so often, especially if you do lots of low speed city driving, when the EGR circuit is working overtime at low temps.
I should have said, the EGR is active only at light to mid engine speeds and throttle pedal positions. If you boot it, it will ramp out the EGR.
Hope that is of interest. How do I know all this crap - I work for a company who develop diesel engines (including the upgraded TDV6) for cars and get involved in the calibration of all this stuff a lot.
20th Dec 2011 12:17 am
henry-john
Member Since: 22 Feb 2011
Location: Belgium
Posts: 337
@ rich, if you're so close to the action, can't you and a few mates work out a system to be able of blanking the 3.0 TDV6 engines EGR's?
and maybe give a hint on how to for the 2,7 TDV6?
20th Dec 2011 12:53 pm
rich11235
Member Since: 19 Dec 2010
Location: Henfield, West Sussex
Posts: 22
Blanking EGRs
@ Henry - well there's a challenge. Are you ready for some more technobabble?
Presumably the problem is with post 2008 vehicles which would be subject to more stringent Onboard Diagnostics (OBD) requirements? If you blank EGR on earlier non-OBD-ed vehicles everything is OK (I believe)?
On later OBD vehicles, blanking off the EGR will create a permanent airflow (MAF) error which will trip the MIL (check engine lamp). WHy is this? Because the the EGR system is controlled by the MAF sensor. Think about it this way - the MAF sensor measures fresh air going from the air filter into the turbo compressor. Downstream of the compressor and intercooler (and just before the inlet manifold) is the EGR connection. So when the EGR is active, the engine breathes the measured amount of fresh air going through the MAF plus the amount of EGR coming through the EGR circuit (depending on the opening of the EGR valve). WHen EGR is off, the engine just breathes in the measured fresh air coming through the MAF.
Imagine at a certain speed, the engine can breathe 100 "units" of stuff (the units doesn't matter - and the stuff can be fresh air or a mixture of fresh air + EGR). If I want no EGR, I set a target MAF of 100 units, and the ECU makes darned sure the EGR valve is closed so that the MAF sensor reaches that target 100 value.
If I want, say 40% EGR, I set a target MAF of 60 units. The ECU opens the EGR valve which admits EGR which displaces fresh air (remember the engine can only breathe 100 units of stuff in total at this speed) so the MAF sensor reading falls until it reaches a target value of 60.
You can see its a little bit like the boost (MAP) sensor controlling the turbo, set a target sensor value, the actuator (turbo vanes or EGR valve) moves until that target is reached. Remember - MAP controlled by turbo, MAF controlled by EGR valve
The problem comes with OBD. If I've set a target of 60 MAFs, but some bunny hating eco-hooligan has blanked off the EGR valve, the EGR valve can open as much as it likes but the target will never be reached. The OBD will see a target value of 60 but a measured feedback value of 100 and say "EGR valve stuck shut" and throw a MIL fault, and probably go into limp home.
To solve this problem, you need to find someone clever with the electronics, who can either:
- hack into the ECU to set the target MAF to 100 instead of 60 (i.e. make it demand no EGR, therefore you wouldn't even need to blank it off)
- hack into the ECU to set the threshold of MAF error that trips the OBD system to a suitably high value
- hack into the MAF sensor to "subtract" the missing 40 MAFs so that the ECU doesn't see an error
I'm not that person I'm afraid, but I am sure there are people on here who are. I'd wager the third one is easiest.
However I can't condone MAF blanking off as it's there for a reason - to kill Nitrogen Oxide (NOx) emissions, which is implicated in acid rain and smog formation. Anyone who lives near a busy road intersection would not thank you if everybody blanked off their EGR and all diesel cars ran round with unregulated NOx emissions. Your call though...
20th Dec 2011 7:57 pm
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
Location: Off again! :-)
Posts: 72911
Waaaaaaaaaaay too techie for me!! Just glad my EGRs are blanked & not going to be a problem again.
20th Dec 2011 7:59 pm
rich11235
Member Since: 19 Dec 2010
Location: Henfield, West Sussex
Posts: 22
Tsk! Evil bunny hater!
I din't expect many people to understand or be interested, but I'm sure there's a couple on here who might be able to take the info and do something useful with it (like devise a way of defeating the OBD)
20th Dec 2011 8:21 pm
uktivo
Member Since: 13 Oct 2011
Location: Staffs
Posts: 139
Well I've had the map sensor cleaned today and I've (and the boss) had seen a massive improvement in performance. The car feels totally different on acceleration. Not had time to see any mpg improvement..
Question.
Should we now blank off the egr? If so, approximately, what sort of cost would an indie be?.
Also, would we have any issues come mot day?..Selling my wifes Audi A3 2.0LTR FSI DSG Sport to help pay for her D3
Pictures in my gallery
21st Dec 2011 8:09 pm
rich11235
Member Since: 19 Dec 2010
Location: Henfield, West Sussex
Posts: 22
There's no test for NOx emissions in the MOT, only smoke. So no problems there. In fact removing the EGR will actually make smoke slightly better
21st Dec 2011 10:13 pm
Disco Dunk
Member Since: 07 Dec 2011
Location: Canterbury
Posts: 88
MY05 - 93k - EGR's not blanked - sensor almost completely gunked up, hole just visible. Gave it a quick clean in the dark last night, will give it a proper go in daylight
22nd Dec 2011 9:33 am
Leesbay
Member Since: 20 Dec 2011
Location: rainford
Posts: 1581
2006 53k checked after reading the posts, andmine was gunked up too. Cleaned with ethanol and refitted. No difference in mpg or performance, but i feel much better now, so that counts for a lot!....................................................................................................
If my wife ever sells my stuff for what she thinks I paid for them, you lot are gonna get some bargains!
22nd Dec 2011 9:29 pm
malky
Member Since: 27 Dec 2007
Location: Sydney
Posts: 59
Someone asked about a D4 - I have a 2011 2.7L diesel that recently required a MAP clean at 14000 Km to fix fuel usage problems. Dealer job under warranty.
I asked about the EGRs which were OK but they also said it is not possible to blank them on current models.
[See explanation by rich11235 in this thread Dec 13]
Still playing with ELM327 and Torque +======
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+--(O)-------(O)--+
TDI 300 and D3 MY06 SE and Shiraz D4 MY11 with Faerie Lites
31st Dec 2011 4:16 am
caverD3
Member Since: 03 Jul 2006
Location: Oberon, NSW
Posts: 6922
The first option rich mentioned would be ideal. No physical work needed.
Could this be done with re-map or is it embedded deeper.
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31st Dec 2011 4:29 am
fukovski
Member Since: 26 Dec 2011
Location: on the sunny side
Posts: 13
i'm sure this can be done with a remap, question is what part of the map needs to be set to 100 and what bit needs to be compensated. theres lots of mappings in the 2MB flash file. i've had a look with winOLS and it found lots in 16bit mode so havent a clue where to start. dont fancy fuggling about with it to be honest incase the engine gets infarkted up.
i also run with good fuel plus additives which should keep excrement levels down.
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has blanked off the EGR valve, the EGR valve can open as much as it likes but the target will never be reached. The OBD will see a target value of 60 but a measured feedback value of 100 and say "EGR valve stuck shut" and throw a MIL fault, and probably go into limp home.
