Well there were a few issues at work there but yes  Cam

2011 TDV8 Vogue in Stornoway Grey

HI all

Just bought a L322 4.4 TDV8

incredible car, loving it so far but the hesitancy of the throttle at low speeds is frustrating. looking at getting a superchips remap to improve things (bit of extra grunt would be nice also!) I have used superchips on many other cars and always been impressed by them, wondered if anybody on here had used them on their 4.4 tdv8? and does it cure the hesitancy or day you have to delete EGR/ DPF to make that alot better?

Cheers Paul

Hi Paul and congrats on the new purchase. I would suggest reading this thread in full for a full answer or at least the last 5 pages or so. Long story short, yes. Cam

2011 TDV8 Vogue in Stornoway Grey

Hesitancy and lack of power are not normal so fix these faults before thinking about a remap  2012 TDV8 Vogue (L322)

Clean the MAP sensor for starters - it can make a huge difference. Use a spray cleaner. However the donut could be very clogged and cleaning it (after removal) is a messy job.

It doesn't sound like he reckons there's a fault here, more that he doesn't like the engine response which in the context of this thread is quite relevant. Of course common issues can cause problems in this area, but and I could be wrong, it doesn't sound to me like Paul thinks he has anything more than standard characteristics he's not keen on... Cam

2011 TDV8 Vogue in Stornoway Grey

JayGee wrote:

Sorry I should have made it clear in that extract from the WM that the regulation of intake temperature only happens during the regen process and is necessary to prevent damage to the DPF and I don't think the EGR is used to regulate intake temps during normal driving. Did the tuner say to physically blank the EGR as if the throttle plate is still closing on overrun in normal driving it suggests the ecu is still thinking there is an EGR valve. No fuel is burnt on overrun so if the EGR opens it's not contributing to soot and is just an economy feature but as you say a bit of engine braking can benefit drivability. How many miles have you done with this mod and have you monitored the regen frequency and EGR temps during a regen?

In diesel engines in particular, EGR systems come with serious drawbacks, one of which is a reduction in engine longevity. For example, because the EGR system routes exhaust gas directly back into the cylinder intake without any form of filtration, this exhaust gas contains carbon particulates. And, because these tiny particles are abrasive, the recirculation of this material back into the cylinder increases engine wear. This is so because these carbon particles will blow by the piston rings (causing piston-cylinder-interface wear in the process) and then end up in the crankcase oil, where they will cause further wear throughout the engine simply because their tiny size passes through typical oil filters. This enables them to be recirculated indefinitely (until the next oil change takes place).[9]

Exhaust gas—which consists largely of nitrogen, carbon dioxide, and water vapor—has a higher specific heat than air, so it still serves to lower peak combustion temperatures. However, adding EGR to a diesel reduces the specific heat ratio of the combustion gases in the power stroke. This reduces the amount of power that can be extracted by the piston, thereby reducing the thermodynamic efficiency.

EGR also tends to reduce the completeness of fuel combustion during the power stroke. This is plainly evident by the increase in particulate emissions that corresponds to an increase in EGR.[10][11]

Particulate matter (mainly carbon and also known as soot) that is not burned in the power stroke represents wasted energy. Because of stricter regulations on particulate matter (PM), the soot-increasing effect of EGR required the introduction of further emission controls in order to compensate for the resulting PM emission increases. The most common soot-control device is a diesel particulate filter (DPF) installed downstream of the engine in the exhaust system. This captures soot but causes a reduction in fuel efficiency due to the back pressure created.

Diesel particulate filters come with their own set of very specific operational and maintenance requirements. Firstly, as the DPF captures the soot particles (which are made far more numerous due to the use of EGR), the DPF itself progressively becomes loaded with soot. This soot must then be burned off, either actively or passively.

At sufficiently high temperatures, the nitrogen dioxide component of NOx emissions is the primary oxidizer of the soot caught in the DPF at normal operating temperatures. This process is known as passive regeneration, and it is only partially effective at burning off the captured soot. And, especially at high EGR rates, the effectiveness of passive regeneration is further reduced. This, in turn, necessitates periodic active regeneration of the DPF by burning diesel fuel directly in the oxidation catalyst in order to significantly increase exhaust-gas temperatures through the DPF to the point where PM is incinerated by the residual oxygen in the exhaust.

Because diesel fuel and engine oil both contain nonburnable (i.e. metallic and mineral) impurities, the incineration of soot (PM) in the DPF leaves behind a residue known as ash. For this reason, after repeated regeneration events, eventually the DPF must either be physically removed and cleaned in a special external process, or it must be replaced.

As noted earlier, the feeding the low-oxygen exhaust gas into the diesel engine's air intake engenders lower combustion temperatures, thereby reducing emissions of NOx. But this simultaneously makes combustion less efficient, thus reducing fuel efficiency and compromising power. (These losses are in addition to the losses created by the DPF backpressure and the extra fuel burning for active DPF regeneration.) The translates into the need for a bigger, bulkier engine. Alternatively, the engine can be operated at a higher rotation speed, which in turn also increases mechanical wear and reduces lifespan.

With EGR, the normally "dry" intake system of a diesel engine is now subject to fouling from soot, unburned (and semi-burned) fuel, and also oil in the EGR bleed gas. Although airflow into the engine remains high, the mixture of exhaust gas and fresh air is also combined with oil vapor from a positive crankcase ventilation system (PCV) system. This tripartite mixture (i.e. exhaust gas, fresh air, and oil vapour) can cause the buildup of sticky tar in the intake manifold and valves. This mixture can also cause problems with components such as swirl flaps, where fitted. (These problems, which effectively take the form of an undesirable positive-feedback loop, will worsen as the engine ages. For example, as the piston rings progressively wear out, more crankcase oil will get into the exhaust stream. Simultaneously, more fuel and soot and combustion byproducts will gain access to the engine oil.)

The end result of this recirculation of both exhaust gas and crankcase oil vapour is again an increase in soot production, which is merely masked by the DPF.[12]

In addition to the abrasive contaminants that EGR systems bring into the combustion chamber, and also given that exhaust gas contains water vapour, modern cooled EGR systems also induce the formation of both nitric acid (from NOx) and sulphuric acid (since some sulphur remains in low-sulphur diesel fuel). These acids will be introduced into the combustion chamber via the intake valves, whereupon they will enter the crankcase via piston blow-by. Because these acids are highly corrosive to metal, the resulting increase in engine oil acidity can be expected to also reduce overall engine longevity.[13]

Although engine manufacturers have refused to release details of the effect of EGR on fuel economy, the EPA regulations of 2002 that led to the introduction of cooled EGR were associated with a 3% drop in engine efficiency, thus bucking the trend of a 0.5% annual increase.[14]

With all of this extra wear, it seems odd that new engines are seemingly not needed on a regular basis. My Sprinter is now at over 500,000 miles, My Allroad 310,000+ and my Touareg over 280,000 miles, all still running well, not using oil and have EGR system in tact.

Maybe this additional wear isnt really significant?

What are the references in your post ie [9], [10] etc, is it a cut and paste from somewhere? BMW i3 Electric Car
2012 Full Fat RR 4.4 TDV8 (now gone)
2006 VW Touareg 3.0 TDi V6

It's from the Wikipedia article.

Thanks. BMW i3 Electric Car
2012 Full Fat RR 4.4 TDV8 (now gone)
2006 VW Touareg 3.0 TDi V6

New type or EGRs takes exhaust after DPF, so its much cleaner and free from soot particles.

telly-addict wrote:

It doesn't sound like he reckons there's a fault here, more that he doesn't like the engine response which in the context of this thread is quite relevant. Of course common issues can cause problems in this area, but and I could be wrong, it doesn't sound to me like Paul thinks he has anything more than standard characteristics he's not keen on...

@faukstad - searching for a solution to a problem that for almost all TDV8 4.4 owners simply doesn't exist. Don't we have enough other issues to deal with? If I was TDV8 3.6 owner it would be a different story. 2012 TDV8 Vogue (L322)

Mine's MAP sensor was well clogged with soot again after less than 2000 kms since it was last cleaned and the air inlet (donut) had accumulated another significant layer of soot and oily muck and the engine side of the butterfly too since it was all cleaned 4 years ago. An EGR-delete remap will occur shortly.
I've been cleaning the MAP sensor every time that I realise that fuel consumption has increased, after which fuel consumption goes back to its normal range for a while. Unfortunately the engine doesn't get a decent work-out to keep it clean, spending most of its time at low revs on light throttle, ingesting exhaust far too much of the time.