D4 VEA 'check engine' light / EGR fault thread

[Flux]

Glad to hear you haven't suffered the same issues. Maybe Volvo's de-tuning software patch was [allegedly] on a lunch break (or sneakily letting down bicycle tyres - baah) when yours was plugged in!

[The Tinkerer]

Originally Posted by Arianne

Under hard acceleration the EGR doesn't attempt to recirculate the exhaust gasses because prime importance is given to performance in such circumstances.

EGR is only done at VERY light throttle input (i.e. when bimbling around at a constant 30 / 40mph on a flat road in town), and on a trailing throttle (i.e. foot off the pedal) to reduce NOx emissions.

In these conditions, the engine is running (relatively) low boost pressure, so there's less oxygen available for complete combustion which means higher NOx emissions. In these conditions, one way to reduce NOx is to reduce combustion chamber temperatures - so the EGR valve is open to allow some exhaust gas to mix with the fresh incoming air. This reduces the heat of combustion and also slightly reduces the amount of fuel used.

When you want to accelerate, you squeeze the throttle which injects more fuel, increases combustion and exhaust temps, which in turn increases boost pressure and squeezes more air (therefore oxygen) into the combustion chambers. At this point the EGR valve will shut, because more oxygen means less NOx is produced per combustion stroke.

The EGR will re-open again when you lift off the throttle - it's a constant, dynamic process.

I wish I could inspect Arianne's and 007's cars as I believe there could be something obvious like a badly routed / kinked vacuum hose, which can also contribute to these symptoms.

The twin-turbo setup on the VEA D4 is really simple, there's no variable nozzle mechanism or anything fancy, just two wastegate flaps .... but the actuators that control these need a good strong vacuum signal to work properly.

Over the next few days I'll try and get some definitive under-bonnet pics of all the vac tubes, what systems they control, and how best to route them. My own S60 has certainly benefited from careful routing of the tubes, and the replacement of one which was too short from the factory.

[Arianne]

@ The Tinkerer,

That's very helpful, thank you. The images you are offering to post would be good to see and may help. So if you could follow this through we would all be grateful.

Very specifically, do you have an opinion on whether detuning the car's performance at the lower end of the rev range would be good, bad or indifferent to the likelihood of EGR valves sticking open, closed or just being clogged?

This is, in all likelihood, going to probably be impossible to resolve unless someone, somewhere finds a dealership that's prepared to take the suspect car under their wings and really seek to see what's happening with the small turbo, various pipes, ECU and low-end torque. I have a feeling that's not going to happen.

You know, there comes a point when it's over? The point when you just admit that this is the way it's going to be, even though you know from the pit of your stomach that the car's performance has dropped off? I think I have reached that point. We'll keep trundlin' around for a while yet but I can't see myself 'taking her out for a spin' like I did a few months back when the car was delivered back on to my drive having received what felt like the Nitrous Oxide treatment from my local dealership.

To all you D5 AWD 215bhp owners out there........good choice! I'll have to put this one down to experience.

Ah well.

Arianne

[The Tinkerer]

Originally Posted by Arianne

@ The Tinkerer,

That's very helpful, thank you. The images you are offering to post would be good to see and may help. So if you could follow this through we would all be grateful.

Very specifically, do you have an opinion on whether detuning the car's performance at the lower end of the rev range would be good, bad or indifferent to the likelihood of EGR valves sticking open, closed or just being clogged?

I will do the pics -- hopefully over this coming weekend.

Unfortunately, it's almost impossible to say if (or how) reshaping the low-rpm torque curve would affect EGR operation on this specific engine, there are so many variables involved, from boost pressure, to fuel requirement, to particulate output, to the actual NOx emissions target.

That said, it easily should be possible for Volvo to balance the various needs and still have good driveability and throttle response. That's why the small turbo is there, to spin up quickly and deliver relatively high boost at low rpm, for good response.

[harvsurrey]

I will add a little more to my thoughts on this , egr problems , and this is a BMW and audi issue as well so don't think this is specific just to volvo as others have suffered as well .
Alot will also depend on your driving style what tye of journeys you do.

i will confess to maybe being little more heavy footed than some and thus as the Tinkerer rightly explains won't have had so much issue as i don't drive on a light throttle that often .

The great benefit of the vea D4 was the power , acceleration , mpg and for business users a gr/CO under the magic 100 figure

I am going to look into seeing where my car is on a power run with surrey RR if i get a chance to find the cost tomorrow ,and i will explain to them why .

I hope i can tell if there is a noticable difference before and after , i have 30 years experience in motorsport as a driver so am fairly atuned to noticing diferences in throttle response and performance .........

Also while the torque is good , don't kid yourself its like a V8 , i have one of those sitting outside and its not in the same league , if you look at my sig i have 4 cars across which we proberly have a full compliment of varying torque and power outputs that are all performance based .

and when i say if i have a long slog to do , the volvo is the choice every time , it as an all round package is a very competant one .

in its class currently the only car that is a close rival on an all round package is the new mercedes c class .

I will make some calls tomorrow including my volvo senior tech , who is very good when i ask him about how what and why on the volvo .

[Arianne]

@harvsurrey

Respect & thank you too.

Arianne

[NigelDay]

Apologies if this has already been covered in this (or other 'Turtle' posts) - but is there any evidence the use of Shell V-Power (or other Premium Diesel) helps alleviate the EGR issues ?

[The Tinkerer]

Originally Posted by NigelDay

Apologies if this has already been covered in this (or other 'Turtle' posts) - but is there any evidence the use of Shell V-Power (or other Premium Diesel) helps alleviate the EGR issues ?

Not sure if there is any evidence to show this. The EGR problems were originally caused by the EGR cooler leaking small amounts of coolant that mixed with the exhaust gas, making a sticky goo which gummed up the EGR valve. Most cars have had new coolers fitted which stop the leakage.

It's claimed that premium diesels produce less soot / particulates, but I've yet to see any hard evidence that definitively proves this.

[The Tinkerer]

I've written a new thread about sorting out the vacuum line routing on my own car, here: http://www.volvoforums.org.uk/showthread.php?t=229612

I never had a problem with the driveability and response of my car - but as my username implies, I like to have a good root around with my cars & bikes, and I usually find something which could be done better. I hope it's useful to someone else.

[Arianne]

Originally Posted by NigelDay

Apologies if this has already been covered in this (or other 'Turtle' posts) - but is there any evidence the use of Shell V-Power (or other Premium Diesel) helps alleviate the EGR issues ?

We have run nothing other than Shell V-power diesel since we took delivery of the car. There are few things on this topic of which I can be certain but this is one of them - it makes absolutely no difference that we've used V-power diesel, as you have read from our posts.

Arianne