EGR butterfly valve - does it ever open if the vacuum line is disconnected and plugged?

[Benjamis]

What opens the butterfly valve in the EGR? Is it controlled purely by the ECU via the vacuum line, or do other forces like boost pressure act on it?

Is it a problem at all that I have block off plates on either side of the flex pipe connecting the EGR cooler to the EGR? That pipe cracked because the bolts holding the cooler to the intake manifold either wiggled their way out or were not put back in by previous owner or mechanic.

 

[garciapiano]

The vacuum control valve controls the EGR which is controlled by the ECU. Leaving the line disconnected will throw a CEL. Blocking that pipe shouldn’t have an effect other than effectively bypassing the EGR. The system just knows it’s actuating the valve but to my knowledge it can’t measure whether gas recirculating is actually occurring.

 

[Benjamis]

I'm not getting a CEL, and the CEL definitely works.
So if that pipe wasn't cracked and I didn't have the block off plates, the only difference is the exhaust would travel an additional foot to the EGR, which never opens because the vacuum line is cut and plugged, but the ECU thinks it opens and closes it, unless someone went in with VCDS before. I might end up getting that soon.

 

[turbodieseldyke]

The system just knows it’s actuating the valve but to my knowledge it can’t measure whether gas recirculating is actually occurring.

I thought it looks for a change in MAP, and throws CEL in the rare event the number isn't quite what was expected. My 98 came with a blocked vac hose (ball bearing), and it threw a code occasionally until i replaced all the vac lines and VAGCOM'ed the egr to a minimum.

Somebody here did a writeup on adding a solid state relay and resistor, to fake air pressure readings to the ecu, as if egr was working. Something like that.

 

[Abacus]

I thought it looks for a change in MAP, and throws CEL in the rare event the number isn't quite what was expected. My 98 came with a blocked vac hose (ball bearing), and it threw a code occasionally until i replaced all the vac lines and VAGCOM'ed the egr to a minimum.

You are correct. In addition, blocking the weep hole on the bottom will cause it to hang open and result in low power. I can’t tell you how many I’ve seen over the years are like that.

 

[mcon]

I thought it looks for a change in MAP, and throws CEL in the rare event the number isn't quite what was expected. My 98 came with a blocked vac hose (ball bearing), and it threw a code occasionally until i replaced all the vac lines and VAGCOM'ed the egr to a minimum.

Somebody here did a writeup on adding a solid state relay and resistor, to fake air pressure readings to the ecu, as if egr was working. Something like that.

how does one find that write up for the resistor install.

 

[Abacus]

I believe the post was by Dieseljunkie (Steve), who I do not believe is on the forums anymore and does not come up when doing a member search. Too bad as he was a great guy. I do remember it was in the A3/B4 subforum but a search on "EGR resistor" in that forum returns 25 pages of results, and I could not find it doing a quick scan. I'm sorry I don't have the time to wade through all them to find the actual post. I think he also added a light at one point since it is a variable resistor and would fake out the ECU since it returns variables rather than constant readings. Good luck and sorry I couldn't help more.

 

[turbodieseldyke]

It was a solid state relay, not a resistor. (edit: i guess it was both.)

Here's the thread. https://forums.tdiclub.com/index.php?threads/egr-delete-on-ahu-poor-mans-version.424543/

Unfortunately, the wiring diagram pic was hosted at a county animal shelter. Not there anymore. LMAO. And we thought photobucket was bad.

 

[Steve Addy]

We need to get some of these older things in a sticky at the top. There's lots of upgrades / improvements that have fallen away just because they're old. It would be nice if we had a general sticky for these things.

TDT and Abacus remembered this one fortunately, and I have a vague recollection of it, but a lot of new members would not know if it was covered before or how to go about it.

Just my .02 on the matter...

Steve

 

[mcon]

I believe the post was by Dieseljunkie (Steve), who I do not believe is on the forums anymore and does not come up when doing a member search. Too bad as he was a great guy. I do remember it was in the A3/B4 subforum but a search on "EGR resistor" in that forum returns 25 pages of results, and I could not find it doing a quick scan. I'm sorry I don't have the time to wade through all them to find the actual post. I think he also added a light at one point since it is a variable resistor and would fake out the ECU since it returns variables rather than constant readings. Good luck and sorry I couldn't help more.

Thanks for the info I will see what I can dig up.

 

[yadic]

We need to get some of these older things in a sticky at the top. There's lots of upgrades / improvements that have fallen away just because they're old. It would be nice if we had a general sticky for these things.

TDT and Abacus remembered this one fortunately industrial valves manufacturer, and I have a vague recollection of it, but a lot of new members would not know if it was covered before or how to go about it.

Just my .02 on the matter...

Steve

Hi, so I finally got my bike out on the road, and I've got an engine warning light. Checked it out with the diagnostic tool & the code I'm getting is saying Exhaust Valve Intermittent. Does anyone know about diagnosing & overhauling these? I see that the servo is around £400 for parts alone & that the valve is prone to seizing due to rust. I don't much want to buy a whole new muffler just for it to happen again so I think the best thing would be to learn to remove it, clean it & overhaul it. If the part's just seized it should be freeable, right, or maybe if the cables are worn, just put in new cables?

 

[Abacus]

Hi, so I finally got my bike out on the road, and I've got an engine warning light. Checked it out with the diagnostic tool & the code I'm getting is saying Exhaust Valve Intermittent. Does anyone know about diagnosing & overhauling these? I see that the servo is around £400 for parts alone & that the valve is prone to seizing due to rust. I don't much want to buy a whole new muffler just for it to happen again so I think the best thing would be to learn to remove it, clean it & overhaul it. If the part's just seized it should be freeable, right, or maybe if the cables are worn, just put in new cables?

What are you even talking about? Bike? Cables? Servo?