A £1.50 engine upgrade for D4 VEA owners
 

I've been very happy with my VEA D4-engined car since getting it last year, but recently I made a simple tweak which has made me even happier with it, improving part-throttle pick up and throttle response, especially in the up-to-2,500rpm range.

Having a look under the bonnet, I noticed that the vacuum hose highlighted in the image below was curved at a rather sharp angle:

http://s27.postimg.org/cy4cg33ab/Vol...rear_small.jpg

That hose delivers vacuum to the actuator that controls the bypass valve for the high-pressure (smaller) turbo. At idle, or when there is zero throttle input, the bypass valve is open as there is no vacuum in the hose. The open bypass valve allows the exhaust gas to flow equally to the high-pressure smaller) and low-pressure (larger) turbos. This minimises boost pressure at low rpm / zero throttle.

When you touch the throttle, the solenoid switches the vacuum supply to the hose, and the actuator closes the bypass valve. This diverts all the exhaust gas to the high pressure (smaller) turbo, to quickly increase boost pressure off-idle. It's this hose and bypass valve that basically governs driveability and throttle response in everyday driving conditions.

With the hose curving at a sharp angle, I wondered if it wasn't narrowing or kinking the internal diameter of the hose, reducing the rate of vacuum increase seen at the actuator - thereby affecting the bypass valve actuation.

The factory-fit hose is an approx 15cm length of conventional 6mm internal diameter, 11mm external diameter rubber vacuum hose. It's only just long enough to fit between the solenoid and the actuator.

I replaced it with a 20cm length of 6mm ID/11mm OD vacuum hose from my local car parts shop. The extra 5cm length is easily enough to allow a nice, smooth rounded curve in the hose with no risk of it narrowing or kinking. The factory hose simply pulls off the barbed nipples on the solenoid and actuator, and the new hose fitted simply by pushing it in place. You don't even have to remove the engine cover to do it.

Total cost: £1.50 for a new piece of hose. Total time: 5 minutes. Throttle response is now more sensitive, sharper and more positive around town and on the open road. It was good before, but this has made it even better.

Of course, this particular vacuum hose was a just a bit too short on my car. Other people's cars might have a slightly longer piece of hose fitted from the factory, in which case they probably won't experience any difference from swapping the hose. But I'd recommend any owner of a car with a D4 VEA motor should have a look under their bonnet to check if their car might benefit.

Thanks for that info..............only would that be classed as a modification and (potentially) invalidate warranty?

I know that might sound a little daft as you haven't effectively 'modified' any aspect of the telemetry but you know how any excuses can be given sometimes ..... .

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A few minutes later.............the post just reminded me that I need to add some screen wash. Had a look but my engine doesn't look anything like the one on the picture (OK I know it's got an engine cover) so will be leaving mine well alone as would probably end up doing something fatal and the tortoise might return...and not leave....or tell the dealer I've been 'tinkering'.....just like The Tinkerer!

Simple - keep the original factory piece of hose and swap at service time.

Also, the above pic shows the engine from the rear (i.e. from the side nearest the bulkhead). I will try and get an underbonnet picture that highlights where the hose is, but it's fairly easy to find. It's at the back of the engine bay, just behind the top right-hand side of the engine cover as you look at it with the bonnet open.

impressive !

from the pick above i wonder if the tube is so short and kinked to meet a height restriction for a certain installation ?

Even with my custom 5cm longer hose, it's still lower than the top of the engine cover so there's loads of clearance all around, both under the bonnet and from the bulkhead.

I believe it's simple cost-accounting by Volvo - using the minimum amounts of material possible.

A quick update for anyone interested in this little mod. I did it 3 weeks ago and it really has noticeably improved driveability and pickup in all conditions - urban / town driving and open-road / motorway.

I measured the factory-fitted hose that I removed from mine and it is 15.6cm in length, which was just a bit too short to connect the vacuum solenoid to the actuator without a sharp curve.

I firmly believe that when vacuum is switched to the hose (which only happens when you touch the throttle), the sharp curve in the hose was sometimes being tightened by the sucking action, restricting the vacuum seen at the actuator.

My replacement silicon hose (6mm ID, 11mm OD) is 20cm long, making a nice smooth curve.

Thought I would bump this thread as it is interesting and useful.

Regards

The reason being ? The ongoing turtle message.

Yes hence why I linked to it, and as post #7 plus when I first read it I thought 'interesting that,worth remembering for a later date'

Regards

Computer probably said it was long enough. They are not owned by Ford anymore.

Thought I would give this a whirl - hopefully this does the job (once cut to length!)

http://www.amazon.co.uk/gp/product/B...ilpage_o00_s00

The ebay listing title says 6mm internal diameter, but the detail text says 5mm internal diameter. Did you check with the seller that it was 6mm ?

Would 5mm v 6mm make much difference ? Cross section area would be 19.6 v 28.3 mm squared, ie a 44% reduction !!

Well spotted! I'm guessing the 5mm/10mm is a typo but I have messaged the seller seeking confirmation. I will let you know what they say.

Here are a couple of 'as installed' photos to make things clearer. Obviously, these pics show my aftermarket hose, NOT the factory original.

Here's the underbonnet pic of my S60, the solenoid and hose is highlighted: removing the engine cover does make it easier to see but you don't actually need to remove the cover to do the job.

http://s8.postimg.org/zdzbg2eo5/Volvo_hose_1.jpg

Here's a close-up of the vacuum solenoid. The hose to be replaced is the thicker one, arrowed: just pull it gently but firmly off the solenoid.

http://s15.postimg.org/60etv3jpn/Volvo_hose_3.jpg

And here's a pic of the actuator, on the other end of the hose. Again, pull gently but firmly and it will pull off.

http://s8.postimg.org/s727xxt51/Volvo_hose_2.jpg

Your new 20cm hose just pushes into place.

Thanks for the pics Tinkerer.

The seller has come back to me and confirmed that it is a typo in the description and that 6mm/11mm has been dispatched. I will let you know how I get on.

Thanks Tinkerer. I've just ordered from eBay...

http://pages.ebay.com/link/?nav=item...d=140864236100

This is anticipation of delivery this Friday of the new V60 (only four more sleeps to go!).

I might go for a week or two without so I can feel the difference once fitted. I suppose there is no way the performance can be monitored and reported on before/after-style?

I have now made this modification and can confirm that it is very straight forward to do and makes a noticeable difference to performance - throttle response is now sharper at the lower end of the rev range.

Thanks Tinkerer!

@ Turnwood, glad it's working for you. Just out of interest, how long was the factory-fitted length of hose on your car?

It was 156mm on mine, it would be interesting to know if this is a standard length.

I notice that there is some sort of mesh or similar on the end of the hose on mine and indeed in your picture. Do you take the mesh off and put on the new hose or does the mesh stay in place and you thread the new hose through it?

The mesh just slips off the hose once you've removed the hose. If you put it on the new hose, the Volvo dealer will never notice the swap :)

Mine was 159mm - it was kinked around the component that it loops over so it definitely appeared that there would have been some kind of restriction.

Thanks, interesting to know. I inspected the factory hose on mine carefully, and it looked like it had been cut to length using a hand tool, the ends were not perfectly 'square.' Makes me think the lengths of hose are just pulled off a drum on the assembly line and cut individually by the worker who is 'plumbing' the hoses that day - which explains the slight variations in length.

Mine was originally kinked over the solenoid too, and at first I re-routed it so it took a more natural path, but I could see the hose was still a little flattened at the sharpest part of the curve. I needed to lift the mesh cover to see this properly.

Just completed the mod ready for tomorrow's trip to North Wales. The removed hose is 161mm.

I'm going to try this (really safe) mod this weekend!

Always thought the pick-up from idle at a junction was a little tardy, this is definitely worth a try, I was considering polestar later this year when the first service comes due to cure this niggle - somewhat more costly!

I have an auto by the way, dunno if that makes any difference to pick up response?

There is a slight lag with the auto as the fluid flywheel needs to engage to get you moving, though if you floor it you will find that lag pretty well dissappears :)

I correct my choice of words, I don't experience a lack of engine pick-up - it just needs to wake up! Don't want to floor the throttle pulling out from a side road as going to result in unwanted wheel spin and / or torque steer (I'm fwd) Polestar blurb mentions enhancement in this regard if I recall correctly, not sure I can justify cost of p*

It's a lag in throttle response from idle which, as pointed out, means that until the torque converter has enough fluid spinning it there is a perceived delay.

Sport mode helps as the tickover rpm is slightly higher I believe, presumably for this reason. I'll have to do an comparison exercise to test sometime?

I need to try and get in the habit of flinging the gear selector to the left when I know I'm pulling out of side road or roundabout into traffic - but I tend to use sport mode only for the occasional overtaking these days though.

Minor gripes, just me getting used to Volvo's again. Love my car!

Please do report back and let me know your impressions.

A quick tip: the hose is easier to remove when the engine is warm, as it's more flexible. It might need a bit of a pull to remove it from the spigots, but it will come easily enough.

Just measure the length of the hose you remove, and cut the new piece of hose a couple of centimetres longer.

Mine was 16cm... I put 21cm on. Noticeably smoother. And definitely easier when the engine is warm..

If anyone wants some pipe, I bought a meter, so have 80cms ish left

I wish you'd said earlier

I just had to shell out 30pence more than the title of this thread.

What could I have bought with that 30p?

Just a quick question. Would this DIY fix cause an warranty issues ?

I don't see why it would. I discussed it with my dealer yesterday because the rep noticed it was smoother than his to drive. The techs at the garage thought it was a good idea.
Also if anyone has the new D4 AWD, I had one yesterday whilst my car was in getting polestar. The pipe on that is even tighter than than mine was.

Just fitted a 200mm length of hose, easy job.

I removed the rubber engine cover as its simple to do and does give a little more room for the fingers. Mine had wire around most of the hose length, so I slipped it off and put in the middle of the new one so it looks ok / authentic

Only had a short drive so will know any difference once next week's commuting starts so will add any comments later

The one that came off was 158mm by the way
Driving today = there is a difference!
Not sure how to describe it other than a slightly more responsive / eager engine. Maybe the first smaller turbo starts sooner now, or is already spinning whereas before was idle?
I need to drive a bit more to know I'm not just imagining it, but the engine is smoother somehow?

Has anyone put a vacuum tester on this pipe before and after replacement to measure if this actually improves the vacuum available or monitored and compared MAP values at low revs?

Reading the MAP values before and after a pipe swap is probably the only way to test properly. Plumbing a vac gauge into the pipe will change the length, internal diameter and flow characteristics of the pipe anyway, which would skew results ...

I just took at quick look at mine, its an older 2015 181hp version and the pipe does not look all that tight to me....

Do you think this engine would benefit from the cheap mod?

The tiny little pipe to the right of the braided one (you can just see it) looks to be a much tighter angle, although maybe not providing such a critical role!

https://dl.dropboxusercontent.com/u/...604_150157.jpg

It's hard to say without pushing back the mesh cover on the hose to have a proper look.

The smaller-diameter hose you mention is the vacuum feed into the solenoid from the main vacuum manifold, so that's important too - just check its run and curves to make sure it isn't kinking / folding too much.

Changed mine this morning - didn't notice any difference but I tend to leave in the somewhat asthmatic ECO mode most of the time anyway.

The original hose on mine was about 170mm (2016 model year) so it could be that Volvo have twigged in the factory. Replaced it with one that's 200mm.

Considering how hard it was to get the old pipe off this one went on remarkably easily, so if I get the Tortoise of Despair™ on the drive into work tomorrow I'll know what the problem is...

I wonder what Volvo would say if there was an engine issue which was being rectified under warranty and it required them to look in the area where your have replaced this pipe and they noticed that it had been changed?

Not much, as they would have a hard time proving altering the pipe length 30mm would have ill effects or be classed as a significant change to standard specification to void a warranty.

Now altering the software for more performance, or the air filtration, after market lowering etc these things may cause issues as you have potentially altered the specification significantly.

It is still something to consider.