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How To: Simple Tweak to smooth SDI idle/tickover vibrations and rattles


Skezza
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Howdy,

I've actually put this up before, but considering I've now had a few people ask me how to do it, it's probably better in its own thread now, so here's a 5 minute trick using a cheap 409.1 VAG-COM VCDS to smooth out your SDI's vibrations on idle.

OK, quick background, SDI idle value is set to 32768 (903 rpm), which is pretty high and causes engine mounts to wear out quickly and also the unpleasant vibrations and tractor feel when sitting in traffic. Mine was particularly violent to the point that one of my mates said he had a bad back after sitting in there one trip. Heavy idle is a big problem on the SDI engines, because the rubber mounts harden up causing a sickening feel which some people cannot cope with. After some twiddling in VAG-COM, I was able to smooth my idle to the point that I don't feel there's any real need to change my mounts now. I did this by simply slowing the tickover, and that's what I'm going to show you how to do. It's electronically controlled by the ECU so there's nothing you can really get wrong.

Note: All the photos are sourced from Google, so none of these were taken by me and necessarily represent what the Lupo looks like, they're just to guide you. If you need any help though, PM me.

Step 1:

Engine on, take it for a drive, get it up to temperature (it'll naturally vibrate less when warm).

Step 2:

Connect your gear, load up VCDS and click Select Control Module from the main window and then select Engine (01).

general-vcds.png

3. Select Adaptation (bottom right)

open-controller.png

4. You don't need to Login to change the tickover, so just select Channel 2.

5. Now, assuming nobody has messed with it already, the value will be 32768 and the RPM read out should be 903.

RT-VCDS-adaptation01.png

6. Entering a higher value will result in a higher tickover which also smoothed it out, but it's not as effective as going for a lower tickover which you achieve by entering a lower value. VCDS will prevent you going too low/high and stop you at what your car can handle. There's two ways you can go about this. Mine is set to 32683. If you set yours to that, you'll get a smooth Lupo, however every car is different so for me, you should do yours the same way as I did mine... select the value box by placing your cursor in there. You should be able to move your value up and down by pressing the Up/Down arrow. Hold the down arrow on your keyboard and the value will start to drop and you'll feel your car get smoother. Stop when you are happy

7. Fine tune it by pressing the Up Arrow and Down Arrow and finding a sweet spot. If you intentionally go too far, you'll notice that there's no difference in vibration for the last 50 down presses. This is to compensate for colder weather , therefore this isn't the sweet spot because it will make your engine lumpy on cold mornings. You want it at the point where pressing Up adds a tiny bit of vibration and Down removes it, but further Down presses (lol) don't smooth it out anymore, like it's that last bit of vibration and you remove it. It should only take a few minutes to find it, but it's worth it. Your engine will feel nice both cold and warm.

8. Save your value if necessary. Older ECU's don't support Test Mode so it may already be saved. If yours does, make sure to save or note the number down regardless.

And you're done. Enjoy your smooth SDI :)

Edited by Skezza
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I'll try it... I don't have any EGR on my lupo.

As soon as I get a chance to try it, I'll report back. Lower RPMs can lead to low oil pressure on worn engines.

Nice one Skezza :)

I can't see it really affecting the oil pressure in any significant way but I'd like to see from a proper oil pressure sensor rather than an oil idiot switch.
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  • 2 weeks later...

Can you do this with the "free" version of VCDS-Lite or do you need the $99 registered version?

Thanks

Joe

hi mate,

You can do it with any version that does adaptations. Should be fine with free yep.

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  • 3 weeks later...

Well hooked up my cheap ebay cable to VCDS-lite (free version) and had a go. In my lupo reducing the rpm made it worse, but increasing it slightly improved matters. Could only increase it by 50rpm for some reason, but even that helped.

Joe

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Well hooked up my cheap ebay cable to VCDS-lite (free version) and had a go. In my lupo reducing the rpm made it worse, but increasing it slightly improved matters. Could only increase it by 50rpm for some reason, but even that helped.

Joe

Interesting that lowering the tickover on yours made it worse. Was it lumpy? Or heavy vibrations? What were the results after reducing it? If it's lumpy or felt rough to drive, that might be a sign of a blocked fuel filter. When was it changed? Also, did you note down the value in the software. It's possible someone else has changed the tickover as I know it's a common thing with these motors.

Realistically, reducing the tickover shouldn't cause the car to run any lumpier, and if that's the case, it could be a sign of other problems.

I wasn't too keen on increasing it, felt weird when I did, oh and VAG-COM blocks you from taking the tickover higher or lower than your car can handle. I don't know if this is a set value or calculated based on the ECU's readings.

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Normally at idle the whole car vibrates, annoying and noisy, and it almost seems to resonate. Increasing it takes it away from this resonance (if that's what it is) just making it more comfortable. Dropping it just made it feel uncomfortable, hard to describe really. Lumpy isn't the right word, just made the car more unpleasant, possibly due to the lower frequency vibrations. I didn't drive it with this setting though, just reset it. Going to change the engine mount and try again some point in the future.

Fuel filter was changed about six months ago, along with the air and oil filters. It's down on power (gets really smokey above 70mph) so I suspect the inlet manifold is full of carbon. Might clean this out when the cam belt gets done.

Joe

BTW - initial idle value was as per your how to.

Edited by Dr Gummi
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  • 5 years later...

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