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SDI resonance between 1500 and 2500 revs


Martins SDI
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Hello people,

My Seat ibiza MK3 SDI (AQM engine) has a plastic intake manifold, like the image below, and since it was new it makes an audible resonance between 1500 and 2500 revs, especially with the engine loaded.


Arb9wXarwcZbBtDc9qehbg.jpg.d755989073faa028714df93c92e65574.jpg
 

Would you be able to eliminate this resonance if you installed an Ibiza MK4 manifold? The MK4 collector is the one in the following image:


000000075727.thumb.jpeg.c42e9592f5182eecde74ec5aed4efdcc.jpeg
 

Many thanks in advance.

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Resonance is good in SDI engines... more airflow.

Those are choke flaps to make the EGR system work. You don't need them. Replace the actuator coil with a resistor of the same value as the coil.

Welcome to club lupo :)

 

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Hi mk2, many thanks for your answer.

Ressonance could be good, but noise is But noise is bad. 😀 . I think the ressonance can be related with the plastic intake manifold. There will be some way to fix this problem? If I change the plastic intake manifold, with a newer one from recent car, this problem could be solved?

What could be the advantage of delete choke flaps?

Edited by Martins SDI
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mk2, many thanks for this information. I have made a complete cleaning in the intake manifold at some time ago and I have deleted the EGR by adding a EGR delete plate. I only don't disconnected the breather pipe. Should I have do it?

But my really question in this topic is about ressonance in my engine in low revs (aprox 2000 revs), and how I can fix that? Like You can see in above pictures, my intake manifold is diferent from the lupos and early 1.9 and 2.0 SDI engines. For example in Your Lupo SDI, you can hear the same ressonance? (I'm asking because in Lupo intake manifold is diferent) I can hear this ressonance since the car was new. 

Edited by Martins SDI
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On 7/13/2020 at 3:49 PM, mk2 said:

The problems that the choke flap and EGR cause are explained in the how-to:

https://forums.clublupo.co.uk/index.php?/topic/106416-sdi-egr-delete-and-gas-flowing-for-more-power/

You know tell me what is the realy function of choke flap valve in SDI engines?  Under what circumstances does it open and close? 

 

Edited by Martins SDI
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49 minutes ago, Martins SDI said:

mk2, many thanks for this information. I have made a complete cleaning in the intake manifold at some time ago and I have deleted the EGR by adding a EGR delete plate. I only don't disconnected the breather pipe. Should I have do it?

But my really question in this topic is about ressonance in my engine in low revs (aprox 2000 revs), and how I can fix that? Like You can see in above pictures, my intake manifold is diferent from the lupos and early 1.9 and 2.0 SDI engines. For example in Your Lupo SDI, you can hear the same ressonance? (I'm asking because in Lupo intake manifold is diferent) I can hear this ressonance since the car was new. 

not that this is in anyway linked, but at 2000 rpm on full load going up a hill, my exhaust rattles and seems to hit the gearbox lol.. need to space it somehow 

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On 7/16/2020 at 12:23 PM, Martins SDI said:

mk2, many thanks for this information. I have made a complete cleaning in the intake manifold at some time ago and I have deleted the EGR by adding a EGR delete plate. I only don't disconnected the breather pipe. Should I have do it?

But my really question in this topic is about ressonance in my engine in low revs (aprox 2000 revs), and how I can fix that? Like You can see in above pictures, my intake manifold is diferent from the lupos and early 1.9 and 2.0 SDI engines. For example in Your Lupo SDI, you can hear the same ressonance? (I'm asking because in Lupo intake manifold is diferent) I can hear this ressonance since the car was new. 

All my SDIs resonate at around 2200. And loud too; you can feel the power surge when on resonance, so when I do an overtaking move, i make sure that after a gear change the revs are right in the zone, like from3 to 4. So rev to 3300 then change up to 4 and the revs are bang on 2200 for max torque and i can keep on accelarating hard.

If there is a noise that is different around resonance RPM, it could be something is loose or has broken from fatigue?

Hey, i just thought- you might have a dual path inlet manifold, which has two resonance points. The changeover duct might be loose, and might be rattling? If yiu do have a dual path inlet, then you shouldn't change it to a different type of manifold, as it will affect the fuel map.

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22 hours ago, mk2 said:

All my SDIs resonate at around 2200. And loud too; you can feel the power surge when on resonance, so when I do an overtaking move, i make sure that after a gear change the revs are right in the zone, like from3 to 4. So rev to 3300 then change up to 4 and the revs are bang on 2200 for max torque and i can keep on accelarating hard.

Yes, this is the noise that I usually hear, but from what you're saying this could be a problem common to other identical cars. I think the noise is directly related with the intake manifold or air filter tubing. Probably poor parts design. So I questioned whether moving to a more recent intake manifold, for example the VW Caddy SDI or later Ibiza, could help with the ressonance problem. I also noticed that for example, in the Caddy Mk3, in addition to the air filter box, there is a ressonance box:

OBUDOWA-FILTRA-REZONATOR-DOLOT-KOMPL-CADDY-2-0-SDI-Typ-samochodu-Samochody-osobowe-Samochody-dostawcze-Samochody-ciezarowe.jpg.b53f79a32c644916be560878d402c3bb.jpg

Could the ressonance box help with the noise?

22 hours ago, mk2 said:

If there is a noise that is different around resonance RPM, it could be something is loose or has broken from fatigue?

I think not. I've already replaced the air filter box supports with new ones and insulated the breathing tube that goes out to a car stringer.

22 hours ago, mk2 said:

Hey, i just thought- you might have a dual path inlet manifold, which has two resonance points. The changeover duct might be loose, and might be rattling? If yiu do have a dual path inlet, then you shouldn't change it to a different type of manifold, as it will affect the fuel map.

Could You please explain me that point better? My inlet manifold is like that:

1172197272_standard(1).jpg.2a8fc0878514721610d9dcb323b81494.jpgstandard.jpg.90c195d021cdfe8e659759028d3f431b.jpg

Edited by Martins SDI
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