code 2411 re-visited...
08-28-2007, 12:32 PM
#1
AudiWorld Senior Member
Thread Starter
Code 2411 re-visited...
Here is my most recent success at extinguishing the CEL for code 2411 (EGR System). The car is a '93 B4. No EGR Mod. The irritant was an entirely predictable & constant CEL for the subject code while in cruise. This occurred some time after polishing the passage as per the I/M Workshop & replacing all the vacuum lines. Do I know what really fixed it? No; I found & repaired 3 faults at once, which is 2 more than I should have. I know.
Suggested reading: I am going to use as a starting point & borrow a photo from austinado16's quite thorough posts here...
https://forums.audiworld.com/a6100/msgs/68719.phtml;
https://forums.audiworld.com/a6100/msgs/69810.phtml; &
https://forums.audiworld.com/a6100/msgs/70078.phtml,
...because my symptoms & lack of lasting success (till now) have been similar.
What I did was simple vacuum measurements & leak-down tests (used a Mityvac) on the various legs of the EGR related vacuum system & found:
how much vacuum it took to:
-crack open the EGRV;
-slow the rpm at idle;
-get idling engine rpm stutter;
-get idling engine shake & rpm stumble; &
-allow the EGRV to close the passage.
Compared to full engine vacuum, these where all fractions of that.
Also measured what I was getting for vacuum at the EGRV & at the EGR F/V, & confirmed, as a group, no leaks at the connections up to & including:
-the FPR;
-the Check Valve & Vac. Resevoir; &
-the I/M C/O Valve.
Measured the resistance of, & applied voltage to the EGR F/V.
Knowns:
- the EGR Valve sealed closed & fully opened its' EG passage within spec. (see the Bentley);
- the EGR Freq. Valve (EGR F/V) was getting plenty of vacuum from the intake manifold;
- the EGR F/V had the right amount of electrical resistance;
- this (15 yr old?) EGR F/V makes -almost- no noise when connected to 12V & didn't appear to seal well, any port in any direction, when I had it on the bench! I thought that was thee fault, but apparently not.
Next: Faults Found:
(cont'd...)
Suggested reading: I am going to use as a starting point & borrow a photo from austinado16's quite thorough posts here...
https://forums.audiworld.com/a6100/msgs/68719.phtml;
https://forums.audiworld.com/a6100/msgs/69810.phtml; &
https://forums.audiworld.com/a6100/msgs/70078.phtml,
...because my symptoms & lack of lasting success (till now) have been similar.
What I did was simple vacuum measurements & leak-down tests (used a Mityvac) on the various legs of the EGR related vacuum system & found:
how much vacuum it took to:
-crack open the EGRV;
-slow the rpm at idle;
-get idling engine rpm stutter;
-get idling engine shake & rpm stumble; &
-allow the EGRV to close the passage.
Compared to full engine vacuum, these where all fractions of that.
Also measured what I was getting for vacuum at the EGRV & at the EGR F/V, & confirmed, as a group, no leaks at the connections up to & including:
-the FPR;
-the Check Valve & Vac. Resevoir; &
-the I/M C/O Valve.
Measured the resistance of, & applied voltage to the EGR F/V.
Knowns:
- the EGR Valve sealed closed & fully opened its' EG passage within spec. (see the Bentley);
- the EGR Freq. Valve (EGR F/V) was getting plenty of vacuum from the intake manifold;
- the EGR F/V had the right amount of electrical resistance;
- this (15 yr old?) EGR F/V makes -almost- no noise when connected to 12V & didn't appear to seal well, any port in any direction, when I had it on the bench! I thought that was thee fault, but apparently not.
Next: Faults Found:
(cont'd...)
Last edited by Lago Blue; 05-29-2009 at 07:43 AM. Reason: grammer
08-28-2007, 12:34 PM
#2
AudiWorld Senior Member
Thread Starter
1st photo: BMW 3mm I.D. Vacuum Hose (borrowed from someone here, thanks):
<center><img src="http://pictureposter.audiworld.com/124134/bmw_3mm_id_vacuum_hose.jpg"></center><p>
1st Fault: A Leak:
The recently new shiney blue (or red or yellow) thin wall silicone vacuum hose from FLAPS is not a good choice where higher temps such as the EGR Valve connection are encountered. It discolours, looses it grip and fails the leak-down test. It's cheap, easier to get and works fine in a lot of other places; but not here. I replaced it with the good stuff:
BMW P/N 51 73 1 470 035;
Audi Picture by Lago Blue | 1175995 | AudiWorld.com
(cont'd...)
1st Fault: A Leak:
The recently new shiney blue (or red or yellow) thin wall silicone vacuum hose from FLAPS is not a good choice where higher temps such as the EGR Valve connection are encountered. It discolours, looses it grip and fails the leak-down test. It's cheap, easier to get and works fine in a lot of other places; but not here. I replaced it with the good stuff:
BMW P/N 51 73 1 470 035;
Audi Picture by Lago Blue | 1175995 | AudiWorld.com
(cont'd...)
Last edited by Lago Blue; 07-14-2020 at 04:43 PM. Reason: clarity
08-28-2007, 12:45 PM
#3
AudiWorld Senior Member
Thread Starter
2nd photo: EGR F/V Hose Restrictor:
<center><img src="http://pictureposter.audiworld.com/124134/b4_egrv_line_restrictor.jpg"></center><p>
2nd Fault: at the EGR F/V, the EGRV Vacuum Hose Restrictor:
There was insufficient vacuum to open the EGRV fully, and here's the key with this fault; when measured from the EGR Valve end of the hard brown (nylon?) tube. The EGR F/V by itself, at its' outlet, wasn't putting out what was needed, & this plugged restrictor made it worse.
I'd already replaced the soft vacuum hose (see previous post, above) on the EGRV, this lead me to the 90° connector at the other end of this hard brown line. There is a narrow hard black plastic restrictor mounted in the outlet of this soft black elbow (see centre of photo above) which connects to the EGR F/V. Inside is an "X" shaped orifice; & you guessed it, plugged w/sticky black powder; & (cont'd...)<ul><li><a href="http://www.12v.org/maintenance/index.php?section=tr&ss=vac&auto=no&eg r=yes">See Restrictor (item 13) here:</a></li></ul>
2nd Fault: at the EGR F/V, the EGRV Vacuum Hose Restrictor:
There was insufficient vacuum to open the EGRV fully, and here's the key with this fault; when measured from the EGR Valve end of the hard brown (nylon?) tube. The EGR F/V by itself, at its' outlet, wasn't putting out what was needed, & this plugged restrictor made it worse.
I'd already replaced the soft vacuum hose (see previous post, above) on the EGRV, this lead me to the 90° connector at the other end of this hard brown line. There is a narrow hard black plastic restrictor mounted in the outlet of this soft black elbow (see centre of photo above) which connects to the EGR F/V. Inside is an "X" shaped orifice; & you guessed it, plugged w/sticky black powder; & (cont'd...)<ul><li><a href="http://www.12v.org/maintenance/index.php?section=tr&ss=vac&auto=no&eg r=yes">See Restrictor (item 13) here:</a></li></ul>
Last edited by Lago Blue; 09-05-2015 at 10:43 AM.
08-28-2007, 01:08 PM
#4
AudiWorld Senior Member
Thread Starter
Last photo & some questions: EGR F/V Vacuum Reducing Screw:
<center><img src="http://pictureposter.audiworld.com/124134/b5_egrfv_vacuum_reducer.jpg"></center><p>
3rd fault: Vacuum Leak:
The EGR Freq. Valve was leaking vacuum. More specifically the black Vacuum Regulating (i.e. reducing) Valve which is clipped to the EGR F/V was leaking. This is the one with the adjusting screw.
I believe this item is just a simple vacuum reducer to (factory adjusted?) limit the amount delivered from the EGR F/V proper, to the EGR Valve itself.
In fact the leak could be heard once I had it removed from the car to test (I also recently began to hear a whistle noise while in cruise). Some have (anti-tamper?) sealant (see photo, round white circle in centre of black "hour-glass" shape) on the screw-head itself, mine had only a slight remainder of same. The slot in the head was already exposed & I could not tell if it had been adjusted before. The top of the screw-head was recessed slightly in the raised housing surround & it took 7 "half" turns to gently bottom out.
Removed, the adjuster is a S.S. machine screw w/very fine threads & a hole drilled in its' centre from the bottom, part way up, to meet a cross-drilling through its shank. On the shank, betweem the head & the cross-drilling, is a shallow recess for the O-ring.
The O-ring was laying down inside the bottom of the plastic housing, beneath the screw when I removed it. This (out of position) item was the vacuum leak's cause (or so I initially thought), as the bolt shank itself is not an air tight fit in its' housing (I could stop the leak by placing my finger on the raised housing surround for the screw). That is the key here & note I had an absence of sealant on the screw head!
There was "dirt" (more black powder(?)) inside the black plastic Vacuum Reducing Valve Body.
There is a recess cut into the screw-hole of the housing above the threads that I believe is the -outlet- vacuum passage (to the brown EGRV line) & -not- for the O-ring. If this is true, then perhaps vacuum could pull the O-ring down off the screw shank? Perhaps only if the screw is fiddled with &/<b>or if the sealant was missing?</b>
However, if the O-ring got pulled down off the shank, that might explain the recent instance of my EGRV being stuck fully open (very bad idle) -before- I got the whistle noise, as the O-ring could be sucked into the plastic body recess & holding vacuum & that valve open?
The recess itself looks as though it would line up with the 2 holes in the shank sides of the adjusting screw (in the "fully open" position). I put the O-ring on the screw shank recess, between the shank-holes & the screw-head. A tiny wipe of syn. grease & re-installed just so the top of the screw head was flush w/its' raised housing. So that is "open" a little more than before. Nothing scientific I'm afraid.
That's it. Put it back together, cleared the code & it worked. Am I confident the EGR F/V works as it should? Not at all!
Now that I've got a fully functional EGR System, do you think I'm anxious to do the EGR Mod & "disable" the thing? No! When I get a blank piece of paper & draw this system & try to explain it to myself, I just don't yet get that mod for the reasons it purports to work. My primary concern: I get no useable vacuum in my noise damper that could be used or amplified to open the EGRV.
Is conversion to a "no EGR System" (see vacuum diagrams at 12V.org) possible?
Lastly, where is the dirt coming from? I suspect that same Plenum (or Noise Damper) connection. Every time the engine shuts down & because its smokey in there (I'm thinking the source is the nearby crank-case vent tubes that also connect & vent into the Noise Damper) & the vacuum, all the way back to the EGRV is being relieved, that relief air (black line to noise damper) brings the dirt in & maybe that's a reason to do the mod? What do you think?
3rd fault: Vacuum Leak:
The EGR Freq. Valve was leaking vacuum. More specifically the black Vacuum Regulating (i.e. reducing) Valve which is clipped to the EGR F/V was leaking. This is the one with the adjusting screw.
I believe this item is just a simple vacuum reducer to (factory adjusted?) limit the amount delivered from the EGR F/V proper, to the EGR Valve itself.
In fact the leak could be heard once I had it removed from the car to test (I also recently began to hear a whistle noise while in cruise). Some have (anti-tamper?) sealant (see photo, round white circle in centre of black "hour-glass" shape) on the screw-head itself, mine had only a slight remainder of same. The slot in the head was already exposed & I could not tell if it had been adjusted before. The top of the screw-head was recessed slightly in the raised housing surround & it took 7 "half" turns to gently bottom out.
Removed, the adjuster is a S.S. machine screw w/very fine threads & a hole drilled in its' centre from the bottom, part way up, to meet a cross-drilling through its shank. On the shank, betweem the head & the cross-drilling, is a shallow recess for the O-ring.
The O-ring was laying down inside the bottom of the plastic housing, beneath the screw when I removed it. This (out of position) item was the vacuum leak's cause (or so I initially thought), as the bolt shank itself is not an air tight fit in its' housing (I could stop the leak by placing my finger on the raised housing surround for the screw). That is the key here & note I had an absence of sealant on the screw head!
There was "dirt" (more black powder(?)) inside the black plastic Vacuum Reducing Valve Body.
There is a recess cut into the screw-hole of the housing above the threads that I believe is the -outlet- vacuum passage (to the brown EGRV line) & -not- for the O-ring. If this is true, then perhaps vacuum could pull the O-ring down off the screw shank? Perhaps only if the screw is fiddled with &/<b>or if the sealant was missing?</b>
However, if the O-ring got pulled down off the shank, that might explain the recent instance of my EGRV being stuck fully open (very bad idle) -before- I got the whistle noise, as the O-ring could be sucked into the plastic body recess & holding vacuum & that valve open?
The recess itself looks as though it would line up with the 2 holes in the shank sides of the adjusting screw (in the "fully open" position). I put the O-ring on the screw shank recess, between the shank-holes & the screw-head. A tiny wipe of syn. grease & re-installed just so the top of the screw head was flush w/its' raised housing. So that is "open" a little more than before. Nothing scientific I'm afraid.
That's it. Put it back together, cleared the code & it worked. Am I confident the EGR F/V works as it should? Not at all!
Now that I've got a fully functional EGR System, do you think I'm anxious to do the EGR Mod & "disable" the thing? No! When I get a blank piece of paper & draw this system & try to explain it to myself, I just don't yet get that mod for the reasons it purports to work. My primary concern: I get no useable vacuum in my noise damper that could be used or amplified to open the EGRV.
Is conversion to a "no EGR System" (see vacuum diagrams at 12V.org) possible?
Lastly, where is the dirt coming from? I suspect that same Plenum (or Noise Damper) connection. Every time the engine shuts down & because its smokey in there (I'm thinking the source is the nearby crank-case vent tubes that also connect & vent into the Noise Damper) & the vacuum, all the way back to the EGRV is being relieved, that relief air (black line to noise damper) brings the dirt in & maybe that's a reason to do the mod? What do you think?
Last edited by Lago Blue; 09-10-2015 at 02:33 PM. Reason: clarity
08-28-2007, 09:03 PM
#6
AudiWorld Super User
Join Date: Feb 2004
Location: Canada (NCR)
Posts: 7,677
Likes: 0
Received 0 Likes
on
0 Posts
2nd that. Good job man. I like the pic of the Last photo: EGR F/V Vacuum Reducing Screw
good pic if you frogot where the lines went.
what is the stokcolour code for the vac lines?
was it Green? or Blue? for IM Swich over vlave?
Brown for EGR?
??? for Vacuum charge form vacuum "ball"?
These colours were usd in the plastic "hard lines" in the system, also in the braided vacuum line connections seen in pic (one of them is green)
This info would be gr* to add to the picture.
what is the stokcolour code for the vac lines?
was it Green? or Blue? for IM Swich over vlave?
Brown for EGR?
??? for Vacuum charge form vacuum "ball"?
These colours were usd in the plastic "hard lines" in the system, also in the braided vacuum line connections seen in pic (one of them is green)
This info would be gr* to add to the picture.
08-29-2007, 04:42 AM
#7
AudiWorld Senior Member
Thread Starter
This coloured diag. connects the dots for you...
The only component I think is missing from this drawing is the restrictor.
<center><img src="http://pictureposter.audiworld.com/57225/vacuum_diagram_bulletin_in_color_website.jpg"></center><p>
<center><img src="http://pictureposter.audiworld.com/57225/vacuum_diagram_bulletin_in_color_website.jpg"></center><p>
Last edited by Lago Blue; 09-10-2015 at 02:42 PM. Reason: clarity and to re-post the illustration.
Trending Topics
08-29-2007, 05:55 AM
#9
AudiWorld Senior Member
Thread Starter
In austinado16's posts that..
I humbly suggested one read (near the top in the first bit of this thread). He's done a lot more detail work than I. Then perhaps (I'm hoping) you can help me with my questions.
I'll also try x-posting this, never done that before.
I'll also try x-posting this, never done that before.
