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bigalcoholic 05-08-2008 11:25 PM

removed small 90 degree intake, now code po432
I have a stock 2001 jeep wrangler 4.0, 6 cyl with automatic transmission. I have been reading on many forums that replacing the stock airbox, hose, and filter with an after market intake such as AEM, would increase horsepower and possibly gas milage.

After looking at the stock airbox, I noticed the hose from the manifold is a much larger diameter than the 90 degree bend hose that is located in the front of the air box filter, the hose were air actually enters the filter box. Because of this, I removed the small 90 degree bend hose, which left a large hole in the front of the air box for air to enter.

Not only did I notice a much better sound from the engine, but the acceleration from a dead stop increased as well as hitting the gas at 40 mph, were it really wants to move.

After driving for 3 days I got check engine light code PO432. I understand this has to do with the cat being out of the spec range. What does this code mean in non-technical terms? Do you think it was caused by removing the small intake pipe? Since I haven't put many miles with on the jeep with the small intake off, what effect do you think this will have on the gas mileage?

mr4x4 05-08-2008 11:57 PM

I have a K&N open filter and no codes have ever shown up
that code is for the cat
you need to have the cats checked

Ripcord 05-09-2008 12:08 AM


Riptide63 05-09-2008 07:56 PM

I agree, the elbow should have nothing to do with the catalytic converter performance. Probably just coincidence that it came up right after you removed the elbow. When I had my '04, I ran it for a good while without the elbow with no problems whatsoever. It picked up 2 tenths at the local 1/8th mile... just enough to lay the smack down on my buddy's Taurus. :D

spanky 05-09-2008 08:42 PM


Originally Posted by Riptide63 (Post 227622)
... just enough to lay the smack down on my buddy's Taurus. :D

haha!!! :rofl:

Jerry Bransford 05-10-2008 10:56 AM

That elbow is commonly referred to as the 'trumpet'. Its sole purpose in life is to speed up the air flow so the air intake is quieter. That's the only reason it is louder when you remove the trumpet, not that the engine is getting any more air since the trumpet easily flows all the air the engine is capable of consuming.

Even last month's Jp magazine confirmed via a dynometer test that removing the trumpet does nothing good for the engine's performance. What removing it will do is give water easier access into the engine since that is the trumpet's second purpose, to help keep water out of the engine.

I'd put it back in. Jeep's engineers designed the STOCK air intake system to easily flow more air than the engine is capable of consuming. No kidding, no rumor. This is right from the horse's mouth, so to speak... Senior Jeep engineer Jim Repp (known as the Rubicon's creator/"father") has confirmed that several times over the years, including in a personal conversation I had with him 4-5 years ago when we were talking on the phone about something else... I asked him about the air intake.

SOME engines benefit from freer breathing air intakes, like the Mustang 5.0L and Camaro Z-28, but not the 4.0L since its air intake is definitely not restrictive in the least. :)

Triple88a 05-10-2008 03:49 PM

Jerry forgot to mention about the trumpet getting cooler air with the trumpet on.
Colder air > more (but warmer) air.

This is the reason why i moved my intake from

to there

and now i'm planning on swapping the stock box back on with a snorkel of some kind.

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