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Discussion Starter · #1 ·
Hello everyone!

I'm owning a VW Golf GTE 2015 model for about 6 weeks. After the purchase everything was fine, but after around 2 weeks I noticed some weird sound when accelerating, it was something like a cracked pipe around the turbo.

I took it to the VW service, and they built something into it but that did not solve the problem. (It was some repair-kit to the rod system of the turbo geometry)

Now I hear this blow-off sound. Sounds kinda cool, but there isn't any blow-off valve in my car and I don't know who should I take my car to. It only appears aroun 2000-3000 rpm, and only when releasing the gas pedal while on the go. In "N" and standing it can't be heard, neither when the DSG is shifting gears.

Now I'm posting it here, because first I'd like now if your car does this sound too ?! If yes, is this normal? Or what can it be?

Video:

Thank you!
 

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It's certainly turbo related and possibly an aftermarket external blow off valve. If not then something is very wrong with the wastegate. Is there any hesitation in acceleration? Normally a stuck wastegate will cause overboost which will cause the ECU to cut fuel or ignition.
 

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Discussion Starter · #3 ·
It's certainly turbo related and possibly an aftermarket external blow off valve. If not then something is very wrong with the wastegate. Is there any hesitation in acceleration? Normally a stuck wastegate will cause overboost which will cause the ECU to cut fuel or ignition.
In the VW Service, the technicians told me that there is no blow off valve installed, at least the did not find it. I don't experience hesitation in the acceleration, maybe only when it's running with the e-ngine and i kick it down, she needs some time to shift back and turn on the ICE (but i guess that's normal).

They fully disassembled my car even to the last piece and found nothing wrong. :/
 

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They fully disassembled my car even to the last piece and found nothing wrong. :/
The sound that you recorded is not normal, so they missed something. I'd try sending the clip to another VW dealer and ask them to confirm that it's normal.
Did you buy the car from a VW franchised dealer?
 

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Discussion Starter · #5 ·
The sound that you recorded is not normal, so they missed something. I'd try sending the clip to another VW dealer and ask them to confirm that it's normal.
Did you buy the car from a VW franchised dealer?
No, purchased from an individual ex-owner.
 

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Call the last owner and say to them that one of your mates who also has a GTE loves the noise that yours makes and wants to know how to get his to sound the same. Hopefully he'll be happy to tell you how clever he was to make the changes.
 

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Discussion Starter · #8 · (Edited)
Saw this post about the wastegate. Maybe of some help- Link
Thank you I’ll see it. The wastegate usually makes a rattling sound around the actuator, and VW tried to fix that but they told me it works perfectly well.

What I mean by that is I took the car to the VW and they fixed the rattle noise of the actuator, but this blow-off sound must be something else.
 

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Is it exactly the same sound each time? There isn't a chance a previous owner has installed an electric dump valve simulator? (I.e. just a speaker?)
 

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Discussion Starter · #10 ·
Is it exactly the same sound each time? There isn't a chance a previous owner has installed an electric dump valve simulator? (I.e. just a speaker?)
It varies a bit but almost the same. I think if something was installed, the VW service would notice that ... :D
The wastegate actuator rattle sounds different, it is not that.
 

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Its a turbocharged engine, it absolutely has a "blow-off valve", AKA dump valve or diverter valve. Its there to prevent the compressor being damaged by the forces incurred when the throttle plate is abruptly closed. Factory installs redirect that airflow back to the inlet tract.

They always make some noise, but its generally pretty well damped and not that noticeable unless your really listening for it. Remapped cars with higher boost pressure is often a bit more noticable too. My A4 runs 1.5bar of boost with a factory recirculation valve and does make a "tish" noise when you snap the throttle shut at full boost. But its only noticable if your actually listening for it, and not generally obvious over the noise of the engine.

Aftermarket valves can be fitted, which dump to atmosphere rather than recirculating. These make the noise much more obvious. Aftermarket air filters can also remove the factory damping and make the noise more noticeable.

Hearing the noise abruptly with no other changes, means one of a few things. A split hose in the factory setup can result in the same thing, however its likely that this would cause other odd running issues. Or, if the valve is faulty or otherwise doesnt open, instead of the air being dumped, you instead hear the actual compressor stall which the valve is there to reduce. Compressor stall sounds a bit different, more like "cha-cha-cha-cha" than a single "tish" type noise.

I've listened to your video a couple times, and potentially its the latter point, a dodgy valve thats not opening. Its kinda hard to make out though.

Sometimes, depending on ECU programming etc, on modern cars the ECU will choose not to open the valve when you shut the throttle, in an effort to keep the intake pressurised and improve transient response. The trade off is a little compressor stall noise. Again, if the car happens to have an aftermarket air filter/intake this would make this effect more obvious.

Having no first hand experience in a GTE i cant really say if its normal or not. Just that deliberately flooring it and then snapping the throttle shut will can make noises exact like those. If it doesnt happen at higher RPM, i suspect its ECU programming and thus by-design, because generally the pressure is no different (or even greater) at higher RPM's and thus the noise should be the same. Really i'd be asking the dealer for more clarity.
 

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I don't know if it's related, but the GTE's gearbox is unique amongst VW group DSGs in that there is an electric motor embedded on the gearbox. One of the useful functions, which I've observed from gathering data, is that the e-motor helps spool the engine down between gear shifts under high acceleration. This allows the engine to shift quicker with less clutch wear.

The below chart shows an acceleration up to 70 mph in my car. Blue shows engine revs (right axis), orange shows power from E-motor in watts (left axis). You can see initial E-motor power as engine is started and then E-motor supplements engine through second and third gear at up to 50kW. But between each drop in engine revs the gearbox is declutched from the engine and the e-motor is spooling the engine back by -40kW, the maximum permitted regen. The user doesn't feel this, except that the shifting will probably be a bit sharper than in GTI/GTD.

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I've found no mention of this in any VW technical literature interestingly enough - I would have thought they would have wanted to talk all about it!

But, perhaps it is this effect you are hearing, as the engine is aggressively spooled down after any acceleration.
 

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@tom66 that's actually incredibly interesting! I don't suppose you have that graph but using acceleration in e-mode? When you floor it there seems to be a pause whilst it reaches for the next gear, id be interested to know if it's still doing a reverse spool between changes in e mode?
 

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@tom66 that's actually incredibly interesting! I don't suppose you have that graph but using acceleration in e-mode? When you floor it there seems to be a pause whilst it reaches for the next gear, id be interested to know if it's still doing a reverse spool between changes in e mode?
I do - the e-mode acceleration is much more linear. The car seems to shift like it's counting up gears rather than downshifting aggressively and is usually in 6th gear by 60 mph or so, contrasting GTE/hybrid mode where under aggressive accel the car will be in 2nd or 3rd at that point.

It also downshifts where possible to maximise regen effect as motor can regen the most at higher RPMs.

As it is a hybrid it's designed to always be able to clutch the engine in so it never exceeds engine redline revs in any gear (even though the motor could probably do it just fine), and the only time it drops below 1000rpm is when you are driving at lower speeds, where the clutch would normally slip to regulate engine speed to wheel speed, but in GTE that's provided only by the electric motor for parking maneuvers etc., as long as the battery is sufficiently charged. Those who have regularly experienced their Mk7 GTE at 0 miles range will know that the car will occasionally use the engine for these maneuvers in hybrid mode, but it is rare.

I love this car - I just wish it was more damn reliable!! If I had an unlimited budget I'd definitely keep one for 'hacking', I'd like to see if I could get more power from E-mode, and look at fitting a Mk8 battery into a Mk7 as technically speaking the car is very solid and the blend between the powertrains is impressive. Most recently I noticed on 'hybrid' mode that under lighter acceleration the E-motor and engine blend load together gently to reduce the jerk between the switchover of these modes. It's all rather well done, you can tell VW put a lot of R&D into this platform. A bit like my old plasma TV though, being progressively replaced with the much simpler electric-only vehicle.

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I didn't log e-motor RPM but you can calculate from torque and power when the car is not freewheeling the motor. It shows the e-motor stays around 3000rpm for most of the acceleration so the gear shifting is more rapid as a result of needing to keep this narrow band of operation, I guess this is the peak power point for the motor.

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In GTE (Sport Hybrid mode) the e-motor is limited to 50kW. I haven't found if anyone has managed to unlock full 80kW power fill in, for this mode. It would give the car an extra 30kW, but might lead to the gearbox being destroyed.

Nice thing about GTE mode is that under full acceleration the E-motor essentially fills in for the drop off in power at lower RPMs from the 1.4 TSI. This means the power output is mostly flat over the acceleration range from 0-100 mph or so. This is much more like a Tesla than anyone wants to admit. It's just not quite as powerful. But I think 210hp Golf GTE vs 210hp ID.3 will accelerate roughly identically.

Contrast that to Golf GTI, where there is no hybrid assist, so power will vary over acceleration. It will get to speed quicker, but the power delivery is less smooth. I guess it depends on what you like. I really enjoy the smooth progression of GTE.
 

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Agreed on the power progression. I came from a GTD and it's more enjoyable to drive, to me anyway. I had read about the power restriction in GTE mode.
I think if I was to change anything about the way the whole thing operates it would be to have an option to force the ICE to stay on at all times in GTE, the lag / bogging down sensation as the ICE restarts is a bit irritating, especially on the move
 

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I don't find the GTE cut out to be a big problem, but everyone differs I guess. It doesn't turn off the engine in GTE mode unless you drop below about 40 mph, and at those speeds the E-motor torque/power is effectively equivalent to the ICE for all but the sportiest driving.
 

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In GTE (Sport Hybrid mode) the e-motor is limited to 50kW. I haven't found if anyone has managed to unlock full 80kW power fill in, for this mode. It would give the car an extra 30kW, but might lead to the gearbox being destroyed.
I guess the ‘missing’ 30kW is what has been added to the Mk8 to make it more powerful than the previous GTE models.
 

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Hello everyone!

I'm owning a VW Golf GTE 2015 model for about 6 weeks. After the purchase everything was fine, but after around 2 weeks I noticed some weird sound when accelerating, it was something like a cracked pipe around the turbo.

I took it to the VW service, and they built something into it but that did not solve the problem. (It was some repair-kit to the rod system of the turbo geometry)

Now I hear this blow-off sound. Sounds kinda cool, but there isn't any blow-off valve in my car and I don't know who should I take my car to. It only appears aroun 2000-3000 rpm, and only when releasing the gas pedal while on the go. In "N" and standing it can't be heard, neither when the DSG is shifting gears.

Now I'm posting it here, because first I'd like now if your car does this sound too ?! If yes, is this normal? Or what can it be?

Video:

Thank you!
Have a read of the following posts, may help you:

How to fix 1.4 TSI Turbo Wastegate Actuator Seizing (Servo Motor)
 
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