Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: mike213735 on January 28, 2009, 07:26:21 PM

Title: Whats This?
Post by: mike213735 on January 28, 2009, 07:26:21 PM

I have been looking at pictures online of the engine in 4.0L Cherokees.

Mine is a 1995 Auto and I have a big flat plastic box on top of the throttle body which is like a flat air filter box. This is inline between the air filter and the throttle body.

Any ideas what it is and what it does?

I can supply images if required.

Thanks
Mike

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Post by: scrw on January 28, 2009, 08:30:48 PM

about 1 foot square and a couple of inches deep? if so its a sound muffler, not sure what year they started fitting them

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Post by: Mike Pavelin on January 28, 2009, 08:31:58 PM

It's a plenum chamber.

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Post by: mike213735 on January 28, 2009, 08:48:09 PM

scrw,

Yes, it's about a foot square and a couple of inches deep and made out of plastic.

Can I remove it and just buy the inlet hose that runs from the air filter to the throttle body and if so, would there be any point?

Thanks
Mike

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Post by: Panic mechanic! on January 28, 2009, 08:51:35 PM

there's no point in changing it for the earlier version,apart from that its somewhere to put your cuppa when you are workong on the engine

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Post by: Dave69 on January 28, 2009, 09:19:04 PM

those little or big plastic add on boxes to the inlet system are there for a reason. when a vehicle is developed they start with an airbox and a straight tube to the engine. A calculation for flow and resonance is done, this gives a figure where the inlet will resonate at a peak frequency which then might become intrusive to the driver inregards to noise. this little empty box creates an opposite frequency which cancels out the obtrusive peak frequency thus giving a quiet and acceptable intake noise. This also helps the car to pass the noise homologation requirements.
 if you need to remove this additional box then it will cause no harm to the engine, but replace the intake tube with a hose of the same diameter as the origional so you can put it back to standard if required later.