EGR should we all be more concerned

[tonymaroney]

Hhhmm, that doesn't sound so good any more...I didn't know that the 103kW engine was more prone to issues.
I assume that Vagcom'ing the EGR valve down to a low level also will have a similar effect as putting the staight through pipe in?...ie warning codes get thrown and exhaust temps rise?
I really just don't like the EGR putting all that sludge into the inlet manifold. Some of the photos you see of cars that are about 60K are just incredibly bad. My car blows a hell of a lot of brown particulates out the back (from day one...which may or may not be due to the EGR...more likely the MAF?)...way more than other 103kW TDI's I see. I would hate to know how bad that inlet manifold is after getting excess particulate matter coming back around through the EGR.
I've had the EGR checked and it seems to work, but I am considering replacing it regardless and cleaning as much stuff out of the intake manifold as I can....But other than install a Provent there seems to be no other way to reduce the crud forming via the EGR flow? Correct? (Fuel additives aren't targeting this EGR area, so that's not a solution from what I have read).

A few people have mentioned that the egr valve and intake manifold are very tricky to get off?...what is the main reason for the trickiness? It "looks" easy, but I've been caught out before!

Thanks,
Tony

[Greg Roles]

Tony,

It's a disaster waiting to happen for sure. You can either decide to pull it all apart and clean it out to the best of your ability every 60-80k, but the problem there is how to clean out the black plastic inlet manifold runners, which head downwards after the EGR inlet. These will no doubt block up as well, and any sort of cleaner or residue can become fuel and upon starting you could have a run away situation. I cleaned mine with carb cleaner, let it air for hours, gave it a blow out with the compresser, yet still on starting the next morning it had a bit of a rev. Remember a diesel is throttled by fuel, so putting anything combustable ( including dislodging sludge ) can become like flooring the throttle.

My temporary solution is very illegal and I'm routing the Provent oil vapour into my exhaust. On driving you get a bit of heat into the exhaust and I figure it would burn off, but at idle, when the exhaust temps drop down to below 100 degrees ( amazing hey! ) you can definately smell oil fumes from my exhaust. Not badly so, but no doubt there. I actually turn the car off at the lights most of the time because I'm aware of this and how it may affect others.

I'm about to get the car chipped, and am hoping the tuner can turn off my EGR circuit as my plan is to remove the whole thing and put a plate right up at the exhaust manifold. This is going to raise my exhaust temps, but so too am I going to run a constant boost controlled / EGT controlled water meth system to drop the temps down, so it's going to be a trade off. I have an EGT gauge, and keep an eye on the stock temps, for in the end even if you do hobble your EGR system, all you need do is be aware of the EGT's when you floor it, and just minimise your time above 650-700 degrees C. Gale Banks and Bullydog, some of the major diesel tuners in the USA reckon 1250 -1350 degrees F is about the upper end of safe for any turbo for any sort of longevity.

There have been three 103kw turbo's go pop that I'm aware of, after tunes, but still I think you'd simply have to install a gauge, do all you can to get the inlet charge cool ( Cold Air Inlet, intercooler water spray, heat wrap the inlet ) and just drive to your EGT's.

There's certainly going to be a lot of TDI's having problems from sludge over coming years as they rack up the miles. Good you are thinking ahead!

[bluey]

But if the diesel burns with less soot using higher cetane fuel - either BP Ultimate Diesel or Caltex Vortex Diesel or a cetane improving fuel additive (Moreys Diesel Smoke Killer or similar), doesn't that eliminate or at least reduce the soot clogging problem?????

Note the VW specs for most cars (not Polo) *require* a high cetane fuel.

I also note that the plastic formed rocker cover is designed by Mann and Hummel for VW to catch blow-by gas liquids.

FYI: Article on cleaning carbon from TDI intake systems

[tonymaroney]

Thanks for the comprehensive response Greg.

You have the 125kW version if I remember correctly so you can fiddle a bit more and tolerate more EG temperature by the sounds of it.

I haven't looked into an EGT guage yet...how involved is the setup, and what parts did you use?

With the EGR valve...when you stomp on the accelerator I thought I read somewhere that it closes the EGR valve? Might be faulty info...but if that is correct then shutting off the EGR altogether may not have "too" much affect on the EGR temp? I actually don't drive the car hard, and only want to do the occasional fast take off etc, but I want to reduce that crud from going into my engine as well. There really does not appear to be an ideal solution to my problem! There's definitely no easy solution thats for sure.

Tony

[Greg Roles]

Bluey I'd recommend everyone planning on keeping any modern diesel past 100k's runs BP ultimate or similar, additives etc, there is simply no better option. You're right in that it may reduce it, but in the end if the car clogs up at 140k vs 100k it's still all bad in my book. The inlet runners are slowly getting smaller, your air flow is steadily reducing, and you'll have to drive the thing harder and harder to get the same power output, plus the max will drop as it clogs. Less air equals more soot, and for the 125kw and 2009 diesels with DPF's that means a quicker permanent clog. All bad news to me!

Yeah I have the 125, and the additional VW designed thermal handling stuff, but there's still going to be the same 1300 degree F ceiling I'm aiming at.

The whole reason behind EGR for the diesel is to reduce combustion temps, which in turn reduces NO emissions. Diesels produce less greenhouse gas, but far more NO which is bad news. Adding exhaust to the inlet charge lowers the O2 available at bang time, and slows the burn, reducing NO output. No other reason they do it. I've no idea exactly how the valve operates, and when, but going by my EGT gauge, only when you're up it does the temp climb anywhere over 400 degrees. In my mind this is when the EGR needs to operate! Either way it's reducing power, and that's what I'm all about.

EGT gauge is easy except for drilling a hole into the exhaust for the sensor. Alternately you could get a scan gauge ala Polar and simply read from the stock EGT probe in the actual manifold, showing true exhaust temps. I'm only seeing post temps, which are apparently 100 degrees or so less than what the turbo actually sees. Drilling into the top of my DPF was a mission, very hard metal, and cutting any sort of thread into it was next to impossible. Still with some liquid metal it's hung in there even when I doubted if it would!

Ideally you'd get a EGT mount ring welded in, and I've got one ready for my forthcoming dump pipe from Gavin on here. Bottom line easiest way would be a scan guage, do a search for Polars one, it reads several sensors which is nice in a compact unit. I wanted choice where I put my sensors, so I have seperate gauges beneath my single DIN aftermarket stereo. see my tinkering begin thread if you're interested there.

Oddly enough all the girlies with no idea point to the gauges and say "I like those..."

Bonus!

[gldgti]

keep in mind that there's no reason (if your getting a custom tune anyway) you cant delete the EGR and have low EGT's - its just a matter of running a little more air. running excess air always reduces the EGT on a diesel - and i've seen this on my own car given i've upped the power significantly yet lowered EGT's just with tuning (running even more boost compared to the extra fuel added).

in the end, running extra air will both reduce the EGT's AND reduce the soot emissions, because it will encourage a more complete burn.

i only make any smoke during a laggy transition now - full throttle is clear as day.

[Greg Roles]

Very good point mate, one facet I hadn't really considered!

[bluey]

keep in mind that there's no reason (if your getting a custom tune anyway) you cant delete the EGR and have low EGT's - its just a matter of running a little more air. [...]

So why doesn't VW just do the more air thing....anyone got any ideas????

[Greg Roles]

Because "more air" involves pushing the turbo harder, and then you run into other problems like efficiency and the far worse "surge" where the impeller basically cavitates. Everything is a trade off.....

[tonymaroney]

Ok I understand most of this but need to clarify a few bits:

By running more air do you mean you get your APR, Oettinger or GIAC ECU flash to actually be individually tuned to run a bit leaner (ie lower Fuel to air ratio) or is it that you dial up more boost and ram more air in there? With the reflash I watched there really was no discussion of extra services like that but I assume you can ask for it at a price.

So my undestanding is that we are looking at three scenarios:
1) Stock...and just to put some numbers in (not accurate, just to compare options 1,2&3) lets say the stock mixture going into the combustion cylinder is:

10ml Diesel
1500ml Ambient Air
500ml of Recirculated exhaust gas from the EGR

this would give us normal operating temps and soot etc.

2) If you remove the EGR valve and put a straight through pipe in (or block it off etc), and a recessed O2 sensor in the exhaust you get:

10ml Diesel (same)
2000ml Ambient Air (changed)

this would give much more O2 for combustion, so better combustion, maybe less soot, and better fuel consumption BUT higher EGT's, possibly cooking the turbo.

3) And lastly if you remove the EGR valve and put a straight through pipe in (or block it off etc) with a recessed O2 sensor in the exhaust BUT ALSO get the car chipped and rebalance the air:fuel ratio (by raising the turbo boost?? Not sure about this bit!):

10ml Diesel (same or it might be slightly less?)
2500ml Ambient Air (changed)

this would give good combustion due to the decent amount of oxygen present, but the heat is drawn away down the exhaust better due to the greater mass flow of air(?).


Is all that correct? To me, if I want to keep the 103kW TDI engine free of EGR oil and soot, but refrain from cooking the turbo I would need to remove the egr, space out the exhaust O2 sensor, and reflash the car and increase the boost pressure? (and install an EGT monitor).
Actually can the ECU change bit for extra boost (or whatever) be done without a reflash? Just via Vagcom?

Sorry for the long post. I am just interested in doing this properly, and preferably without cooking a turbo or two!

Thanks,
Tony