EGR blocked now stalls very easily

[hungabunga]

Not sure how plausible that is but it's better to be on the safe side and I'm glad I could turn it down with vagcom which I suppose is the safest thing to do.
Maybe you should mention this in the other thread as there are a fair few who have blocked the egr.

Thanks
Sully

 

[thebeno]

Hmmm, bit worried now, may unplug mine. Will have a search on the TDIClub website, they will know the answer.

 

[Muttley]

glynnd wrote

I did question this explanation myself as it does not seem logical to me (ex motor vehicle techician 1987) however it possibly is plausible.
The reason for egr is to reduce nox emisssions and to cool the temperature of the exhaust gases and aid cooling of the catalyst.

EGR is solely there to reduce NOx. does this by reducing the peak combustion temperature, how hot it gets when the charge is burned in the cylinder. Under some circumstances (medium revs, high load) the charge gets hot enough to burn the nitrogen in the charge into nitrogen oxides, NOx. Exhaust gas is introduced as the only convenient *inert gas* to reduce the amount of oxygen in the charge which reduces the combustion temperature (and also results in inefficient combustion, increasing the other pollutant from diesel engines, soot)

Disabling the egr increases the temp of the exhaust gases thus incresing the temp in the turbo.

Well, yes, but not by much, and certainly not by enough to damage the turbo which is already running red-hot at full chat.

Why the hell its doing this by introducing hot spent exhaust gases in to the fresh air charge in the cylinder(with the egr working) I personally cant see it.

As I said above, exhaust gas is inert (all the oxygen has been used up) so it reduces the oxygen content. It's a very short transient, otherwise changing the injection quantity would work.

But I am sticking with mine turned down in vag com and the egr connected.

Should have nearly the same effect.

If you are hell bent on disconnecting the egr try inserting a one way valve in the vac line to the egr. Make sure it fitted so it cant suck the egr valve open but can release back the other way, I know there is probably no air to release back but i fitted a bleed valve in mine and the light had not come on after 50 miles!

Interesting. Sounds as though the ECU checks for continuity of the vacuum system by opening the control valves to atmosphere (the EGR and Turbo control valves are 3-way, one pipe connected to vacuum for ON, one to atmosphere (somewhere near the air filter) for OFF and the third line to the control element (EGR valve or turbo vanes/wastegate)

 

[FabiaTDi]

Got myself an Allard EGR replacement pipe today when the remap was done.

Get a bit of shut down shudder but stalling problem doesnt seen to be there as before.

 

[UncleFester]

How severe is this as a direct comparison as it's a recent change.

 

[FabiaTDi]

Wouldnt say the shut down shudder is severe but its noticeable of course.

 

[Phil_beeza]

im wondering if there might be some gunk around the valve open/close bit

is the whole ufo thing hard to remove (to clean) then replace?

 

[UncleFester]

Here it is fester

With the engine warmed up and running at idle in neutral with all major accessories such as air conditioning turned off, connect the scan tool cable and start the scan tool software.

[01 - Engine]
[Login - 11] and enter 12233 as the access code
[Adaptation] and go to block 3.
Give the accelerator pedal a quick "blip" to ensure that the EGR remains turned on for the next minute while you perform the following steps.
Note that the display shows a default adaptation value of 32768 and shows approximately 250 +/- 20 mg/stroke of air intake volume.

If all is well, enter 33768 as the new adaptation value, and select "test". Note that the displayed air intake volume changes, usually to about 370 mg/stroke. The specification limit is 370 mg/stroke, so if you want to remain within OEM shop manual specifications for emission control reasons, you might have to enter a number slightly smaller than 33768. (If you don't care about road-legal NOx emission limits then leave it at 33768. [Depending on the usage cycle, NOx at this setting can be increased by as much as 40%]) If all is well and you have a setting that you are happy with which results in an intake air volume of 370 mg/stroke or just a hair less, enter [Save]. The values aren't exactly the same, but when you enter the value 33768, the ECU will automatically adapt it. In my case it was something like 33628. 370mg/stroke is what your looking for

Done thanks EGR now reconnected, 33628 is what it settled at with an air intake volume of 335mg/stroke.

Cheers

 

[muddyboots]

Going back to the issue of more frequent stalling after the EGR mod.

To those who've had it, is it generally when the engine is cold ?

Thinking back, I've stalled the Passat once or twice when cold, generally when pulling up my sloping drive to get to the road first thing in the morning.

It could be that the hot recirculated exhaust gas is aiding combustion in the same way that glowplugs do, so if the EGR is stopped, the engine could be more prone to stalling for the short period after startup.

 

[glynnd]

The egr does not work until the engine is warm

 

[Red ibiza]

The egr does not work until the engine is warm

Who told you that?

 

[muddyboots]

That surprises me too - I thought that EGR worked from cold, and actually helps warm the engine more quickly.

 

[glynnd]

Guys it was not a statement I dont honestly know I assumed that after two minutes if idling the egr stops so thought there was no reason for it to work until the engine is warm?

 

[thebeno]

Never assume Glynnd, never assume!!

 

[glynnd]

Yes I know