EGR valve inspection/cleaning on 16v/1,4l (BBY) - a complicated task?

[gewstarr]

Hi guys!

My CEL has been turning on more and more frequently, lately. Started about a year ago. Then it was really intermittent, with the P0401 error code showing up now and then.

After resetting, I could run without further re-up of the lamp for a couple of months or so. Now, however, the light comes back on after only days (or even less). Therefore, I've decided to take it seriously and aim for the source.

I cleaned throttle body just the other day. It was pretty black, especially on it's inner side, but this is not the real source of this issue.

Now, I think I've located the EGR/AGR valve on my car, see photo here.

As I've come to understand, all you need to do to remove it is undoing the two bolts. Now, as you can see here, mine is really rusty and probably needs to replacement? Perhaps these will even snap right of during undoing?

Anyways, just looking for quick advice here. One thing dazes me. There is a copper colored pipe entering the valve from under. How the heck shall I proceed to release this? Will it come natural after undoing the two mentioned bolts?

Second, is it okey to disconnect the wiring plug and i.e. try running the car without it (I mean to look for differences since I have a pretty rough idle, especially sometimes) or will this cause some important config to black, meaning I have to do some sort of remap with VAG-COM?

As always, I'm much thankful for any piece of advice I can get here.

Oh, last but not least, if I succeed in removing the valve, and find it to be nasty inside, how should I clean it? Is brake cleaner okey for this purpose?

Cheers!

[Breezy_Pete]

The metal egr pipe will be removable after undoing those two nuts.

The other end of the metal pipe is where any blockage will be though, where it goes into the inlet manifold just under the throttle body.

Did you clean that while you had the TB off?

[gewstarr]

Thanks for your quick response @Wino, helpful as always!

Yeah, I did the manifold as well, yesterday. Brake cleaner and a microfiber cleaning cloth.

 

Now, I was too eager to wait, so I just went out and started trying.

Fortunately, I found a Youtube video that explains the situation on what I think is a VW Polo.

From the looks of the video, this guy is working the exact same engine as I have in my Fabia Mk1.

 

 

To be honest, I more or less fast-forwarded the video, not even with speakers turned on.

Then I went out and started. The mentioned nuts where really stubborn, as to be expected.

Anyways, after spraying them with a ****load of WD40 and some rust remover, I finally got them bolts to start moving.

 

Now, I removed the throttle body once again, just to get better access to the two (5 mm Allen) bolts holding the copper part in there.

Then I got stuck. It felt like something more was holding the copper piece in between, but I couldn't figure out what it was.

Therefor, I abandoned the project and went back in. Now, however, when watching the Youtube video a bit more thorough, I can see what it is.

Just about 1 minute into the video, another screw is visible. What a shame I missed it, since it doesn't sit far away from the manifold.

 

I'll get back on this project tomorrow, but now I have to get off to work (late night).

If anyone has any other piece of advice, please feel free to speak.

 

Again, thanks!

[rum4mo]

Yes, so you missed listening to the music - that might have calmed you, but more importantly you missed the single bolt that supports that EGR gasses pipe!

 

Now, I'm sure that it has been said before, did you make sure that you could see a clear passage through from where that pipe fits on to the TB or I/L manifold - ie a clear path for that EGR gas to pass through, from my limited experience of one car, as Wino said, it does tend to be at the TB or I/L manifold end that the blockage occurs due to the hot exhaust gasses mixing with the oil getting passed into this area from the crankcase. I did not find much to clean on the EGR valve which is typical for petrol engines.

[gewstarr]

Big thanks for your response @rum4mo!

Yeah, well, at least I'm glad I hear I didn't miss any important audible note by not switching the television to HDMI channel! :-)

A real pity I missed that screw, anyways. Actually I did see it but it didn't see the mount to the pipe since it was kind of hidden from my angle. Also, there was at least one more similar screw an inch or so away from it, so I was afraid there was some sort of crucial support for something engine-internal, so at first I didn't dare to touch it. Gash, this sounds lame however I put it, so I'll just say it; I missed an important screw, which held me stuck.

Now, I've succeeded. The EGR is currently lying in the kitchen sink. It doesn't look so nasty inside. I'm pointing a strong flashlight onto it, so inside the hole is more or less visible in this photo below.



Now, how to process? I read on another (non-VW-specific) forum that if you shake the valve you should hear some flapping sound from inside. If you don't, the valve is stuck. Does this checkup apply for Fabia EGR valves as well? I did so, but I get nothing when I shake the thing. Just a solid nothing.

I have recently bought an ultrasonic cleaner that I haven't had any use of just yet. Should I place the valve in a bowl with hot water for a couple of minutes or so?

Some say you should be careful not submerging the electrical part, i.e. where you stick the plug. Is this correct or would this piece be fine with a full submerge into vibrating water?

I'm eager to get on with my project, but I I'll try to hold my horses for a bit, just so I don't do smithing stupid.

Oh, I almost forgot. The copper pipe. Endings (inlet manifold and valve) looked pretty fine, or well at least they were not clogged.

Cheers!

Edited 27 October, 2015 by gewstarr

[Breezy_Pete]

Having (destructively) taken apart one of these valves, I can think of no reason to think that a flapping noise from inside would be a good thing.

 

Did you try blowing through the metal pipe, to be 100% sure there isn't a blockage?

 

I would not get the electrical end of the EGR wet, that's just asking for trouble.

 

Ultrasonic cleaning of the lower part may be of some use, give it a try.

[gewstarr]

I've done almost a handful of session (600 seconds each) in the ultrasonic tank by now.



I've also used steel wool, trying to get a grip inside. I also tried to move the 'cylinder' inside the hole with a screwdriver for leverage. It's completely stuck. Maybe it's ment to be that way, so that only electrical power with high amperage makes it move. Maybe I shouldn't have pulled that stupid screwdriver/leverage attempt at all. Anyways, we'll see later on, if I've managed to brake something. Oh, I was thinking about buying half a gallon of diesel and pour it into the ultrasonic washer. It's probably more effective than just using hot water, like now. Anyways, think I'll pass. Diesel may leave nasty ashes, in comparison to brake cleaner or (even better) carburetor cleaner.

I've also called my local Skoda dealer and ordered two new M8 nuts (OEM # N02300313) since mine was in a terrible condition. They said they'll have them by tomorrow. Oh, by the way, I had great help from Vagfans.info receiving that specific part number. I'm usually good with Workshop-manuals.com but they didn't seem to have an entry on this specific part, only instructions for the 8v/MPI version, as described in sticky post here on Briskoda.net as well.

Now I'll go and get another bottle of brake cleaner, to get a final touch done. Carburetor cleaner would probably be a better choice but these cans unfortunately seems kind of hard to get a hold of where I live.

Edited 27 October, 2015 by gewstarr

[Breezy_Pete]

Did you try blowing through the metal pipe (the one you're calling copper, that I think is really steel), to be 100% sure there isn't a blockage?

 

 

If you can apply 12V between pins 1 and 5 (1 positive), the valve should open fully.  Be careful of generating any sparks near any brake cleaner though.

 

Make sure the breather filter bit (on the short hose) that you have submerged in the picture is dried out fully before you re-fit the EGR to the car.

[gewstarr]

Great advice, @Wino!

Unfortunately, I at most have some simple home electricity 12 power adapter lying at home, delivering 1A or something, at it's best. I suppose this needs five times as much to operate. Of course, I could wire it directly to the car battery, but it would be too much hassle. Think I'll just try and see if it works.

Oh, the other thing you mentioned, that dead end hanging out from the side. I wondered what the heck that was. A filter, neat. Actually, I've now pulled the hose of the valve and let the filter plus hose piece lie in the water tank itself for a while. I also put it to my mouth and blowed, after. Worked a charm; air is coming through, both ways.

Now, left, I accidentally think I found the clog. What I first thought was to be a solid piece of manifold turned out to be another loose component, see here.

This made cleaning so much easier. Now I noticed that there was two passageways that I hadn't even seen because they were totally clogged up. Now I've spent half an hour cleaning. Photo above is an after-shot, before it was totally black and the two openings in the side were not visible at all. Now I'll let it all dry over the night, and then resemble tomorrow. Hopefully I can re-use the gaskets since they're made of metal.

[Breezy_Pete]

Ah yes, the 'intermediate flange' which connects the EGR metal pipe through to the manifold needs to be clear as well. 

Sorry, I didn't think to suggest that, as the BBY engine on my 2003 Polo doesn't have that part; the inlet manifold has that stuff integrated into it, so that the end of the metal pipe looks like this and bolts straight onto the manifold, and therefore if both ends of the metal pipe are clear, there is nothing else to be blocked.

[rum4mo]

As you have said, having cleared that blockage, you will have solved the "insufficient flow" problem. I was reluctant to suggest that there was an intermediate plate - wife's old Polo had one, but I was "pushing" the idea that you really needed to make sure that you could see all the way through from the EGR gas pipe to inside the inlet manifold.

 

Edit:- when I was messing about with the EGR valve on wife's old Polo, I compared the NOS one and the old one from the car, both seemed exactly the same wrt to blowing through each of the openings and with the "ease" that nothing happens when you try to move the plunger!  I think (that I read) that the small pipe with the screen on it is needed to allow some ambient air to pass through the EGR valve under certain conditions.

 

I've always fancied buying an ultrasonic cleaner, there is still time for that - used to abuse small ones at work cleaning Ford Escort crankcase breathers and later on petrol K Jetronic spray nozzles (called injectors).

Edited 27 October, 2015 by rum4mo

[gewstarr]

Big thanks for all your input on this matter guys, much appreciated. So, earlier today I re-fitted everything. Scanned codes before starting the engine. Now I had no less than three codes.

I took a wild guess that the two additional codes simply had popped up there because I had disconnected the EGR plug during cleaning, so I simply cleared them all, and then fired up the engine. It coughed for a couple of seconds, but then it got somewhat steady. Well, not like really steady-steady, but more like this car usually runs. I mean, I honestly don't think the rev needle has been 100% steady on this car, ever, instead it usually rocks up/down around 30~50 RPM, and it was no change in this now. No new CEL light, anyways. Nice.

I then looked under the hood while still idling. I noticed exhaust coming out from the EGR. I had obviously been too careful not overtightening the two M8 bolts, instead leaving a leak. I took my wrench and did another quarter on each nut and it stopped leaking.

Then I closed the hood and took it for a real test run, but just around the block. Felt good, and still no re-up on the engine management warning light either.

Now, later tonight, I decided to take the car for a longer trip. So, I did ~40 kilometers on highway, and somewhere on my way back home the CEL came back up. I stopped at a Maccy D's parking lot and plugged my Bluetooth adapter.

Not the usual code, the one that was the beginning of this entire thread, but a new one, P0402 ("Exhaust Gas Recirculation Flow (EGR) Excessive Detected"). Still, regarding fault code area, for obvious reasons this one is in the same neighborhood as the P0401 ("Exhaust Gas Recirculation Flow Insufficient Detected") code I began this whole issue with.

Any ideas? I'm starting to thing that perhaps I could simply be dealing with a worn MAF sensor, sending crappy data for the EGR valve to act nutty on. Is this a completely insane idea?

Edited 29 October, 2015 by gewstarr

[sepulchrave]

Yes, your car doesn't have a MAF sensor.

 

The code is because you haven't re-adapted the EGR valve, you can't do it without VCDS.

[gewstarr]

Thanks @sepulchrave, I had no idea about this!

Anyways, when I was saying MAF, I was really referring to my air pressure sensor sensor (OEM # 036906051), being located to the left of my engine, while standing in front of the car looking down the engine bay. Doesn't this piece speak to the EGR valve in any way at all?

However, the adaption thing _may_ be doable, at home. As you may have figured out, I have this Bluetooth thing lying around in the glove compartment at all times, but I also have a generic KL/KKL interface, and VCDS-Free installed on a netbook.

I can read codes, measure blocks and stuff, but IIRC there was some sort of limit to which controllers were accessible through the non-paid version of VCDS. I'm currently on the commuter train so can't really go see for myself, so I thought I'd ask to be pre-informed till I get home tonight. Think I can do this?

I assume this is the routine I'll be doing. Pretty straight forward, as it seems. Is there anything that can go wrong during the process? Known hiccups or so?

Edited 30 October, 2015 by gewstarr

[sepulchrave]

The only thing that can go wrong is if the EGR valve is faulty, but you're right, the free version of VCDS can't do it.

[rum4mo]

Did you ever switch the ignition on while the EGR valve connector was "off" - if not maybe you might be okay, if you did then as said one way or the other you need to run adaption on that EGR, either way no harm in running adaption on it and the TB.

 

One other thing, I am trying to remember your previous postings on this car, but, have you ever removed the MAP sensor and cleaned it using something like brake cleaner?  I had "excessive flow" at one time and cleaning the MAP sensor which was covered in oily gunge sorted that - until the "insufficient flow" caused by the blocked ports appeared?

 

All other pipe work intact and all gaskets replaced if looking tired?

[gewstarr]

I'm considering spending that $ 99 getting a licensed VCDS Lite. However, first I'll make sure my cheap wired hook can even see the controller, so that it won't be a complete waste. Of course, dollar isn't anywhere near all time low at the moment, but I still think a garage will quote me (at least) the same money for doing the adaption.

Regarding previous postings, there have been a couple on this lime yellow piece of machine; everything from a collapsed window elevator, seized KOYO PAS, bad control arms / ball joints, to general unaddressable noise. You guys have been incredible helpful on everything. However, I've never done anything engine or manifold related to this car, except for changing all four spark plugs and a single spark coil (these seem to burn like candlelight on this engine) every now and then. But no, nothing else. It would be easily done undoing the two screws/bolts holding the MAP and doing it with brake cleaner, I suppose. I'll give it a try.

One thing I find weird though, the CEL is not turning on instantly, but only occasionally, it seems. Yesterday evening, for instance, I hadn't time to move on with this project, but I had to go to the post office, so I took the car there. After all, it's a couple of miles, and no engine light came up during this trip, and engine felt pretty much normal as well. Are you guys 100% sure the EGR really needs adaption after being disconnected?

And to answer your question @rum4mo; even before I disassembled EGR, throttle body and everything in between, I decided to see if running with/without EGR made any difference to idle, so I simply unplugged it and started up the engine. I couldn't notice any difference, though.

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[rum4mo]

Ah, so you have run the engine with the EGR valve disconnected, oh bother!

 

If you have not already cleaned the MAP sensor, one tip, probably from this forum, was not to direct the spray into the MAP sensor, ie do not hit the sensor itself with the full force of the pressurised spray - but more fill it up with that liquid and shake it about with the open end covered to keep as much of the cleaner inside the sensor housing, repeat this a few times - again this is a tip probably from this forum.

 

My confusion was probably due to me trying to help someone else on this or another forum!

 

The fault light coming on and going off, that just means that the car is operating without faults at times, it "keeps" the light on for a few engine starts after a fault has "gone".

[sepulchrave]

Don't worry about the MAP sensor, it is extremely robust and designed to survive in an incredibly harsh environment, it's absolutely fine to spray solvent into it to clean it, it's NOT ok to poke anything solid in there, you'll see the red thermistor body sticking out of it, the encapsulated piezo membrane is right down inside.

 

As I previously stated you WILL need to re-adapt the EGR valve, even if you haven't run it because the settings will be for a partially blocked EGR system, not the nice clean system you now have, remember the EML doesn't come on until the EGR requested value goes outside what's actually available, it takes many years for the system to block up, you've just put it back to as-new in half an hour.

 

I speak from experience, not guesswork:

 

http://www.briskoda.net/forums/topic/366211-fixing-egr-excessive-flow-fault-permanently/

[Breezy_Pete]

I thought all that happened during adaptation was that the ECU requests "fully open" and "jots down" the resulting potentiometer reading: then it lets it shut and jots down the pot reading there.

Thereafter it knows what pot readings correspond to what percentage opening?

[rum4mo]

That is what I reckon happens, just end stops/limits position voltage recording for future use.

[sepulchrave]

It also clears the learned adaptation values which are calibrated live using the MAP sensor, this is the important part which needs doing, that table of values will be inaccurate which is why the EML comes on after a few miles of driving.

[Breezy_Pete]

Got a reference for that?

[sepulchrave]

If you read the link I posted, you'll see that my EML behaved the exact same way until I ran the adaptation routine, since which I have had no further problems.

 

It is therefore reasonable to assume that the ECU checks the expected EGR flow against actual flow using the MAP sensor during a steady state once the engine is at operating temperature. This is certainly the way I would do it if I were coding the EGR management routine, there is certainly no other way of detecting an EGR malfunction if the valve itself is fully opening and closing.

[Breezy_Pete]

I must admit, I've wondered how this all works, and haven't found anywhere that describes it in any detail.

 

I would have thought there'd be a look-up table of EGR opening percentages for each operating point, and a 'paired' look-up table of MAP sensor readings consistent with everything working as expected.  Only if MAP data (or potentiometer feedback from the valve itself) demonstrated mismatch between expected and actual pressure change or valve position achieved, would a fault be logged.

 

In other words, the engine ECU wouldn't need to learn anything about the EGR position (other than calibrating the pot data) or MAP data, just keep an eye out for departures from 'nominal'.