VAG 1.2 AWY 3 cylinder petrol engine: airbox flap

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Hi,

I do maintenance on a friend's recently bought VW Polo 9N, powered with the small 1.2 3 cylinder petrol engine, 6 valves, 40kW.

The stock airbox have a hot/cold air flap on the atmosphere side, which I believe (from youtube video tests... with heating the stat) is dysfunctionnal. I temporarily locked it in place, and so far the performance is consistent and no CEL came on. Of course it's a purely mechanical device, driven by carefully loaded springs, and a waxstat. It is said to dynamically adjust hot/cold air mix (hot side is on the exhaust manifold shield), depending on rpm, engine load, and near cylinder head temp (from where the stat is positionned when the airbox is mounted).

Is there any adverse known effect, knowing we're in a tropical climate, to purely delete the flap and close the hot and pilot holes ? I can't find the waxstat part alone to replace it and try to see if the flap works correctly.
 
I haven't seen that system on a motor vehicle in some time. Know it used to be real popular back in the day. One of my wagons has a similar system.

There isn't any drawback to deleting this system in a tropical climate. It really only serves a purpose in the extreme cold. Unless your tropical climate gets to freezing temps often (I doubt it), then there is no issue.
 
I always removed such from my cars and installed a better aftermarket air cleaner for max air flow. Never had a problem even in winter.
 
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I did this on a friends Skoda Fabia with no problems, if you do this in a tropical climate watch for throttle body icing, if it doesn't happen you are good to go.
 
Originally Posted by Trav
I did this on a friends Skoda Fabia with no problems, if you do this in a tropical climate watch for throttle body icing, if it doesn't happen you are good to go.

Thanks for the insight! Did icing happened on your friends Fabia?

I deleted many carb heater (coolant or electric) and had no icing problems
 
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Originally Posted by Trav
No, it didn't ice. Some motorcycles were prone to this in hot weather and high humidity, rare but happens.

It's funny how many carbureted small displacement 4 stroke motorcycle have at least an electric carb bore heater (coolant heating for the expensive ones), where their fuel injected counterparts have none.
 
Originally Posted by Superflan
Originally Posted by DoubleWasp
I haven't seen that system on a motor vehicle in some time.



I heard Volvos still used this into the modern era as well. Never had actually witnessed it before. Probably not a bad thing to have in colder average climes.
 
Originally Posted by DoubleWasp
. . .
I heard Volvos still used this into the modern era as well. Never had actually witnessed it before. Probably not a bad thing to have in colder average climes.


Ironically, the "prime temperature" zone for induction icing is 20-70F, meaning of course, that it's not the coldest climates that will see the issue the most. The temperature permitting the formation of the ice is the temp in the induction system where the drop in pressure (that allows a carb to work, and may be helpful or incidental in an FI engine) occurs. Of course, with the drop in pressure, the temp decreases too. And if you add in high relative humidity, you get ice.

I'm pretty sure that many mysterious cases of "rough running" or "misfiring" engines are actually cases of induction ice that go unrecognized for two reasons. First, the outside temps don't naturally cause anyone to think, "induction ice!"; and second, by the time anyone can get a look at the engine to attempt diagnosis, the evidence has, quite literally, melted away.

In the southern US, we see carb ice in light aircraft frequently, and as a result, are quite ready (if you value your continued health...) to select CARB HEAT, a manually operated feature in most light aircraft.
 
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