Thread: TDV8 Egr map out and remap 2010 TDV8

Originally Posted by harlie

There is a good argument for a catch can. The problem with EGR is that the soot mixes with the oil from the crank case vent. A catch can is installed inline to remove the oil, resulting in only EGR soot being routed to the inlet. Without the oil, the soot is less likely to form a think gunk. There are some claiming that an open EGR increases engine/exhaust temps, from my research and testing this is incorrect. Research I've been doing for the VAG side of my garage has told a different side of this story. There is a case for EGR to remain in the later engines as the introduction of exhaust gas into the inlet is primarily to reduce NOx - however this is achieved by reducing the % of fresh air the engine consumes which reduces combustion temps because the oxygen level is lower, this is despite sucking in warm exhaust gas (it is warm not hot as it goes through the EGR cooler). We have confirmed this theory in the 2.0tdi VWs and what it shows is a significant increase in average and max EGTs (hitting 850degC) when the EGR is blocked off, reportedly enough to cause turbo failure. It is to the point that no tuners will tune out the EGR in the later VAG diesels (they are still doing it for the older 1.9 which is a very under stressed engine, down on power and torque by some 45% compared to the 170 2.0). Using what I can only describe as the best diagnostic system I've come across, we can see when the EGR opens and the result is an immediate reduction in EGT. The increase in combustion temp is seen as such a risk that VAG engineers have the EGR default to open if it is unplugged - tested and confirmed. The EGR has such an effect on combustion temps that it is also used for active maintenance of Diesel Particulate Filters (DPF). Now DPF is not of interest to the L322 community as we are lucky enough not to have them, however it does demonstrate how the EGR is used to regulate combustion temps. The follow points are copied from the VW tech training on DPF and descried what the engine ECU does to increase EGTs to 500-650degC during idle!!! Unfortunately the diagrams don't want to copy. ● exhaust gas recirculation is switched off to raise the combustion temperature, ● an extended injection period is initiated, after a period of main injection with reduced quantity at 35deg crankshaft angle after TDC, in order to increase the exhaust gas temperature, ● the supply of intake air is regulated by an electric throttle valve and ● the charge air pressure is adapted so that the torque during regeneration does not change noticeably by the driver. So, it closes EGR, and by over fuelling and blocking air it creates a super-rich mix. It actually does a pretty good job at hiding the process from the driver, only thing I notice is that it is holding each gear a bit longer, and if you switch off when it's halfway done you can smell the heat, and the fans run for a good 10 minutes to cool the engine bay (DPF is just in front of the firewall up quite high) Back on track - the important point for this discussion is that the first thing it does is close (block) the EGR to increase combustion temps. And from what I can see during road testing, it is nearly the only time the EGR is fully closed. All my testing has been conducted on VAG vehicles, and has achieved the exact same results as the tests carried out by the local go faster shop. Given that our RRs are running bosch/siemans engine management which is the same as what VAG run, I can't see that they would be any different. Back to my original point, sorry got a bit side tracked. Installing a good catch can like the Provent 200 or the 43Draft Designs unit would remove the oil from the inlet, greatly reducing the build-up of crud. BTW, don't bother with a cheap ebay can, they don't vaporise enough oil. Those of us with TD6 have removed the EGR, now there is just oil, similar result - without soot, the oil shouldn't create gunk. However, on a side note after the install of the cyclonic oil separator the volume of oil from the CC is making me think about catching it...

Harlie
Any more thoughts on the usefulness of EGRs in the tdv8s? I was resolved to do using induction cleaner every 10,000km. But I might reconsider and go for an EGR emulator or remap.

Would the crank case ventilation filter on a tdv8 do the same job as a provent do you think?

I also note from the workshop manual the crank case vents (post vent filter) to only the driver side turbo, which is next to the alternator.

Hey Pete,

From the testing I have done (you've seen the wife's back Octavia VRs which is identical to a mk6 Golf GTD) I would be hesitant to remove the EGR on any engine that is running the numbers that modern diesels are running.

The TD6 is not what I class as modern diesel numbers and is really a lazy engine so we are getting away with EGR removal, even with a 510nm remap, I am not seeing the temps anywhere near what the VW engine produces when the EGR is dumbied out. There is many cases of failed turbos in the VW camp when guys have played with mappings that significantly reduce the level of EGR available to the engine. As I mentioned above, the tuning companies are now refusing to even reduce the level of EGR for the 2.0 VAG diesels, and it has NOTHING to do with emissions regulations - they are still mapping out the diesel particulate filter!!

Your 3.6 produces bigger numbers (per litre) than my VW engine (standard 125/360 from 2.0) and if you are looking at the (800nm) remaps available, that's getting into scary heat production, I would not be touching the EGR without some concrete data.

The gunk issue is a combination of EGR soot and CCV oil - remove one and the gunk no longer forms. EGR has been always looked as the source to get rid of - in the past we were not dealing with the temps and (IMO) people don't fully understand what the modern EGR is really doing in it's roll of temperature reduction (it's scary!). Way back when I got my first car (1982 model), my dad's mechanic went straight to work and closed off what was the first version of EGR in a petrol engine, with the theory that the engine runs better without the warm, low oxygen air - and he's right!However, the problem now is they run too well, and create too much heat.

The CCV filter on the engine will never remove a good portion of the oil, the simply can't - the vapour is hot at that location and if they are too restrictive the CC pressure builds up. There are two good catch cans available (many crap ones). Provent has a large filter which needs to replaced every 60-80km, the 43DD unit has no filter, it works on condensation and by all reports is the better unit. The can is placed low and as the CCV vapour passes through the can it cools enough for the oil to condensate on the plates.

I would assume you only have one CCV outlet, If it was me, I would fit a quality catch can and leave the EGR be - maybe go to the trouble of cleaning them.


As a side not - I wonder what the VNT mech on your turbos looks like. Would be interesting to look at a "failed" tdv8 turbo - if it is anything like the VW camp (same turbo manufacturer) a lot of the failed units will just need cleaning...

Thanks heaps Craig, very interesting.

From the workshop manual there looks to be a place to divert CCV through a quality catch can.

I know the provent. What's the 43DD?

Originally Posted by harlie

Would be interesting to look at a "failed" tdv8 turbo - if it is anything like the VW camp (same turbo manufacturer) a lot of the failed units will just need cleaning...

From what I've seen the bearing fails, which makes me wonder if the rear sump drain plug has been removed during oil changes.

Originally Posted by rar110

Thanks heaps Craig, very interesting.

From the workshop manual there looks to be a place to divert CCV through a quality catch can.

I know the provent. What's the 43DD?

Sorry - it's 42DD

42 draft designs

Originally Posted by Graeme

, which makes me wonder if the rear sump drain plug has been removed during oil changes.

I remove mine at every oil change, which I do every 10 000km. Oil is cheap, engines and engine repairs are expensive!

I have had alot to do with this problem of EGR in the induction systems and am currently doing a study at rmit on it, what we found is essentially the EGR has many uses in the engine system and should continue to operate as removing them causes alot of different issues within the engine. The way to fix the problem is regular induction cleaning. Some manufacturers do it and others are beginning to now, I believe Mazda just added it to there service schedule for the utes. So really the best option is annual or bi-annual induction cleaning which is good for the engine anyway.
I have attached a blog that talks about the tdv6, which has the same issue.

Land Rover and Jaguar TDV6 induction cleaning and maintenance - Pickards Automotive | Car Service Centre | British and European Specilists | Melbourne

Hi Guys,

is there anybody out there in Aus that has actually mapped out/blanked the EGRs on a 3.6 tdv8. Id be interested to hear what they can report as the results.

It seems to be the preferred way to go in the uk.

On another note, being we are in a hotter climate in Aus Id assume our egrs are in operation for a shorter duration, or have i go that wrong?

I haven't seen reports of too many turbo failures over here, or is that because we have less vehicles.

Cheers Paul