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Old 13th November 2009, 19:26   #1
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Angry Can the engine be tested briefly without the air Filter?

I searched but can't find any topic on this. For the past couple of days I have noticed that my Alto's engine was some what rough / coarse after a cold start and during subsequent warm up. It became normal once the car ran for a while and the engine warmed up. So while going out today I took a small detour and visited the MASS, to have it checked as the second service is still a month away.

The service adviser got in and started the engine, listened for a while and said it was OK. Allowing the engine to idle, he got down and opened the hood. He then opened the cover of the air filter box to look at the filter. Perfectly normal so far.

Then he quickly removed the air filter and closed the lid of the filter box, as the engine continued to idle. Even as I started voicing my concern, he accelerated the engine mildly a couple of times, replaced the air filter, switched off the engine and pronounced everything was normal. The entire episode took less than a minute. He told me it was a standard test they perform while checking such idling issues.

Now as far as I know the engine should never be run without the air filter, and I had never heard of this kind of test. Had I not been standing near the car while it was being checked, this would have gone unnoticed. I am worried whether this could have caused any significant damage, even though the duration was very short. I would like to know the views/ideas of the experts here. God knows what other such "tests" they perform during service!

Last edited by Gansan : 13th November 2009 at 19:36.
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Old 13th November 2009, 19:35   #2
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It's fine as long as nothing enters the cylinders. I've actually driven my ITB'd car (much much easier to damage something because of the location of the intake) a few hundred metres without any sort of filter. However, it's one of those things which are best left to the luckiest people on the planet, living in the cleanest countries in the world.

Edit: Please don't take this as any form of confirmation that it's fine to do this. It's still incredibly stupid and risky. You are asking for serious engine damage when you do something like this.
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Old 13th November 2009, 19:54   #3
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For a brief period its ok.

During regular service, they clean the throttle body without the filter on. All cars go through this.

Shan2nu
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Old 13th November 2009, 20:22   #4
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Cars are sometimes run without the airfilter when stationary. Never run i.e. drive the car without the airfilter.

Cheers,
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Old 13th November 2009, 20:28   #5
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As long as there was not too much dust/sand in the air its ok .

Last edited by jav : 13th November 2009 at 20:30.
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Old 13th November 2009, 22:02   #6
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An air filter is an important part of a car's intake system, because it is through the air filter that the engine "breathes." An engine needs an exact mixture of fuel and air in order to run, and all of the air enters the system first through the air filter. The air filter's purpose is to filter out dirt and other foreign particles in the air, preventing them from entering the system and possibly damaging the engine.

Short intervals will not do any damage but, long term running will destroy your pistons and other engine interiors, If you want your engine to breathe freely go for a aftermarket air filter, there is lot of info in various threads here..
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Old 13th November 2009, 22:32   #7
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dont worry about the test he was probably trying to see whether the start up problem was because of choked air entry.had the same problem in my santro traced to the throttle body which needed servicing
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Old 13th November 2009, 23:41   #8
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Hi Gansan,
there's nothing to worry about as long as the car was not driven around and the test was not conducted in a dusty environment.My car's carb was tuned many times this way for idle speed adjustment.
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Old 14th November 2009, 09:11   #9
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he he its ok your engine will not die on you Its quite normal while tuning vehicles, unless this is prolonged driving around and that too on dusty roads.

Have'nt you seen some drag cars and bikes which run without any air filter for max air flow
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Old 14th November 2009, 09:25   #10
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If the air filter is removed , the engine starts running lean and heats up. A Karizma of one of my friend had a K and N filter, he used complain that the engine heats up quickly.
Bell mouth intake are common on drag racing cars and bikes. Problem with running with no filters is the risk of dust and other particles entering the engine.

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Old 14th November 2009, 09:30   #11
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Its ok if the place was dust free. I myself did it once, removed the filter and started the engine, to listen to the change in sound!
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Old 14th November 2009, 10:39   #12
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Thanks guys, it is a relief. I never run any of my engines,whether car or bike, without the air filter even for a second. I have not yet started any DIY on the car except to wash it, but am used to doing quite a bit on the bike. I clean the bike's air filter myself once in between services, and whenever I remove it I will stuff the intake opening with a piece of clean cloth even though the engine is dead! So yesterday's episode came as a shock.
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Old 14th November 2009, 10:55   #13
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I once removed the air and inserted to twisted piece of metal in the tube connecting the Filter box and carb, just to check what happens,
trying to induce swirl and a bit of turbulence.
But the intake roar made me feel going faster
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Old 14th November 2009, 11:36   #14
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Quote:
Originally Posted by motorpsycho View Post
If the air filter is removed , the engine starts running lean and heats up. A Karizma of one of my friend had a K and N filter, he used complain that the engine heats up quickly.
Bell mouth intake are common on drag racing cars and bikes. Problem with running with no filters is the risk of dust and other particles entering the engine.

Regards
Kiran
Engine would run leaner in carburretted vehicles as the fuel flow is fixed. For racing, the air filter is removed and the fuel flow increased accordingly.

In fuel injected engines with an ECU, the air mass (air flow) sensor detects the increased air flow and the ECU automatically increases the amount of fuel injected.

Cheers,
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Old 14th November 2009, 12:35   #15
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Quote:
Originally Posted by motorpsycho View Post
I once removed the air and inserted to twisted piece of metal in the tube connecting the Filter box and carb, just to check what happens, trying to induce swirl and a bit of turbulence
Hope that piece of metal is big enough not to slip into the intake tube and block the intake flow..

Restricting the air intake size will actually increase the velocity of the air entering the engine and the carb will not be designed to adjust the fuel mixture accordingly on its own, Try increasing the fuel/ air ratio
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