Lago Blue

Now that I have a perfectly serviceable EGR System on a '93 B4, and no more CEL's or codes, what to do? what could I possibly go on about now?

As this is yet another overly long post, and so that I don't just repeat myself, if you haven't already, please read this thread first:

https://forums.audiworld.com/12v/msgs/62046.phtml

My purpose today:

1.) Show how to minimize the amount of exhaust gas recirculated. Why? Because I seem to have a better running engine the less the EGRV is open. How to do this? By causing the CEL to just illuminate, then not iluminate;

2.) Prove the Intake Manifold Change-Over Solenoid (I/M C/O Sol.) can be used in place of the EGR Frequency Valve (EGR F/V). Why? Because it is way cheaper.

3.) Isolate the Vacuum Resevoir (Vac Res.) from the entire vacuum system. Why? Myth-busting: To prove that it is not part of the EGR System.

4.) Confirm the abscence of any flow measurements as part of the EGR System operation. Why? Again myth-busting: To show how really dumb & simple this sytem really is.

I was intriqued to read of the EGR Systen Delete recently (see below); but have some practical concerns, besides the obvious enviro & legal aspects.

Currently, where I live the 4WD nature of the vehicle means I enjoy a rather crude smog check, however, I forsee a day when this will no longer be the case. More & more vehicles are 4WD, they will eventually be tested more thoroughly, and I'd bet that requirements on older vehicles will likely tighten, rather than the reverse, as they are seen to be more of a problem, rather than in the past, when old vehicles where not closely scrutinized.

So as much as I like to contemplate a complete EGR Sys. delete, I'm also thinking I may still have to to have the system in place & fully functional to pass future E-tests. Certainly some of you other folks must be in similar circumstances?

...continued in Part I:<ul><li><a href="https://forums.audiworld.com/12v/msgs/62437.phtml">EGR Delete...</a></li></ul>

Lago Blue

<center><img src="http://pictureposter.audiworld.com/124134/b5_egrfv_vacuum_reducer.jpg"></center><p>
With the above in mind, I wanted to set out what I've learned recently about the EGR Sys. for (even just perhaps just my own?) future reference. Plus I do really hope that I can just forget about it for sometime to come!

1.) I have been closing down EGR F/V Adjustable Vacuum Regulator (see black plastic hour-glass shaped item in photo above) as much as possible. Every few days I turn the screw in towards closed a little more. I am trying to absolutely minimize the opening of the EGRV.

Each adjustment was one complete turn <u>in</u> of the screw (clock-wise) &amp; re-seal of the screw head. I used blue anti-squeal goop for brake pads as it just works well here &amp; I'm doing this alot.

After each adjustment I'd just enjoy the car for a few days. I've long since replaced all the vac. lines; done a leak down test of the system; had the EGRV off to check its function; done the EGR Passage Polish Procedure; replaced the EGR F/V; &amp; had no CEL or codes, all for some time now.

Now I wanted one. Eventually (as I kept turning <u>in</u> the screw) the ubiquitous 2411 returned. After a final adjustment of a half turn <u>out</u> (counter-clockwise) of the EGR F/V A/R Screw &amp; re-seal; the code is cleared, the CEL is gone, &amp; the EGR system operation is now minimized.

I fully expect that the CEL will re-appear sooner than if I left the A/R more open but:
a.) I'd rather enjoy the engine performance with the system minimized; &amp;
b.) Having done both, I'd actually prefer to have to clean the EGR Passage sooner, as it begins to clog (easy); rather than later when it's really clogged (not so easy).

...continued on Part II

Lago Blue

<center><img src="http://pictureposter.audiworld.com/57225/1_bend_tabs_up.jpg"></center><p>
2.) By the fortunate mistake of receiving the I/M C/O Sol. instead of the EGR F/V that I'd requested, I was challenged to answer, what I'd only wondered about previously: could the I/M C/O Sol. work in place of the EGR F/V? The answer is yes, it works perfectly.

The significance is cost. The I/M C/O Sol. is 60% of the cost of the EGR F/V. If you're stuck &amp; must shop there, at the Cdn dealer they where $270 v. $160.

The clips on the back side of the EGR F/V A/R allow you to transfer it to the I/M C/O Sol. You can see the clips on the black plastic A/R (the item on the right) in the photo above.

The bottom line is you now have a cheaper I/M C/O Sol. of a different colour.

...continued on Part III

Lago Blue

Although isolating the Vac Res. disables the I/M C/O function, the EGR System was not affected. It continues to function as before. I simply disconnected its line &amp; plugged both ends &amp; drove the car. No change, no CEL, &amp; no codes. I had suspected this from looking at the schematic but I wanted to physically prove it.

This goes against what audiboy wrote in his explanation of his original EGR Mod (see below with regard to the Vac. Res. (see his 5^th para) but there it is, the EGR Sys is not dependant on the Vac. Res. at any time to operate.

...continued on Part IV<ul><li><a href="https://forums.audiworld.com/12v/msgs/2019.phtml">original EGR Mod explanation...</a></li></ul>

Lago Blue

Having taken it apart several times, I can find no evidence of any sensor in the EGR Sys. that measures any flow anywhere.

I believe the temp. sensor (the only sensor directly in the EGR Sys.) in the EGR Passage of the I/M uses temp. rise as an indirect indicator of flow, but it's guessing. Plug it in somewhere hot &amp; your EGRV would never open. The EGR F/V is simply a solenoid &amp; does no sensing, nor does it send any signal back to the system or ECU.

IMHO the subject solenoid does not "perceive a reduced/diminished volume and a CEL is created". I believe the EGR F/V does nothing more than simply supply &amp; relieve vacuum to the EGRV &amp; uses no exhaust gas whatsoever to do this.

This may be contra to what Mance said below, but there it is.

...continued at Closing Remarks<ul><li><a href="https://forums.audiworld.com/12v/msgs/36125.phtml">Mance's EGR System explanation...</a></li></ul>

Lago Blue

It was kind of fun to find an answer (I think) to a very old question of Mance's that he asked back in '03 (see Mance's Paradox below). I read in a OBD II Training Manual that all the plain vacuum operated EGRV's are either of the positive or negative back pressure type (in that they utilize either pos. or neg. back-pressure in addition to engine vacuum, to help operate the valve) &amp; therfore any change to the exhaust system that will change this pressure will interfere with the EGRV operation. So some speculation here, lets say Mance's exhaust probably reduced the exhaust system back-pressure; &amp; his CEL disappeared, would that point to our EGRV as being of the negative back-pressure type? I'd be happy to hear your theories.

I am also happy to hear that folks such as sdb90 have had success by turning out (opening, counter-clockwise) the A/R Screw on the EGR F/V, but frankly, I have no idea why this helps as my engine always runs best with the EGRV closed!

I would be interested to know the condition of their EGR F/V seal; Adjustable Regulator Screw O-ring; Item 16(?) inline "X" restrictor; &amp; the EGRV itself because to my mind something is amiss if you are (theoretically) supplying more vacuum to the EGRV &amp; causing your engine to run better. Any ideas anyone?

Always more to learn!
David.<ul><li><a href="https://forums.audiworld.com/12v/msgs/7340.phtml">Mance's Paradox...</a></li></ul>

axe_360

I had to change that piece of junk on mine to for code 2411

axe_360

in the books you can deactivate the egr, o2s and the evap by changing a line of code to in the ecm from 0000x to 00009 for manual, 00010 auto(ag4) or 00011 (hp18).

" On Board Diagnostic system, Engine Control Module (ECM)Code Control Module (VAG 1551 function 07.
- Coding versions 00006, 00007, and 00008 are not released for the fuel injection and ignition system. If the ECM is programmed with any of these codings there will be performance problems, increased fuel consumption, higher emissions, decreased transmission life and stored malfunctions that do not really exist.
- By using codings 00009, 00010, or 00011 (for vehicles without oxygen sensors) in vehicles with O2S control; the O2S control, EVAP and EGR systems can be shut off."

quote from elisewin audi DVD

P.S I have not tried it but it sounds interesting

sdb90

and at the same time I am now baffled that my improved performance really doesnt make any sense (in theory). But in reality I noticed such a difference. To be honest I was shocked that SUCH a noticeable improvement was made when I expected nothing at all.

Having driven for a few weeks now with what was done done, I have noticed something. Now, I cant say for fact that this is not just a case a me becoming used to the "new feel" of my car, and as always, wanting even more improvement, but for some reason the extra pep seems to have diminished somewhat. I do still notice a crisper shift(especially 2-3) and maybe better throttle response, but neither, to me, seems anywhere near as clean and/or noticeable a gain as when I first tweaked that screw.

WHY

I was a bit confused to begin with, but with LagoBlues latest findings I am completely perplexed with the gains I achieved. and why are they dropping off?

Lago Blue

Yes, very interesting! Is the VAG-Com tool used to perform this change?

What is the "elisewin audi dvd"?