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ben
Dodge Dakota
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9/08/2004
01:11:37
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 Subject: Whats up with dakotas Cat?
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Message:
I heard dakotas (gennIII) use 3 cats on the stock exhaust... I have a 1999 3.9 4x4 and it only has one? any reasons why. and why dodge put 3 cats on a truck? I have never heard of this and dont understand it.. from all my ford and chevy's ive never had more than one cat on a single exhaust.. why did dodge do this to some models?
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.boB
Dodge Dakota
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9/08/2004
02:49:20
| RE: Whats up with dakotas Cat?
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Message:
To "pre-cats" and one cat. It keeps emissions low enough to meet CA and federal regs, without one large bulky restrictive cat.
According to my service maual, only the 4.7 has all 3. However, last time I looked under my 5.9, there were three cats, and only 2 02 sensors.
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mrman
Dodge Dakota
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9/09/2004
07:30:19
| RE: Whats up with dakotas Cat?
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My 2000 Dak 4.7L has one cat. I think Dodge added the pre-cats to '01 and later models.
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Lurkin
Dodge Dakota
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9/09/2004
09:12:20
| RE: Whats up with dakotas Cat?
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Message:
It also depends on the model/configuration, or some-such, as my 02 QC AWD has a single cat.
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Kowalski
GenIII
9/09/2004
17:34:01
| RE: Whats up with dakotas Cat?
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Depends on where truck is sold and emission laws there. My 2000 came with three.
Lead, follow, or get out of the way
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mrman
Dodge Dakota
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9/09/2004
19:05:39
| RE: Whats up with dakotas Cat?
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Message:
Anyone had a cat that sounded like it was going bad but never does? The cat on my '00 produces a rythmic clatter as I accelerate. The clattering doesn't speed up as I accelerate, it just gets louder. I can't hear it at idle or crusing, but mash the gas and the noise is there. If I rev the engine with a quick punch of the throttle, let's say up to 4000 rpm and immediately let off, I can hear a sharp random metallic rattling noise. I've checked all hangers, clamps, and clearance around the exhaust - all OK. Could this be the catalyst inside the cat slapping back and forth against the shell? If so, why hasn't the catalyst disintegrated and plugged the exhaust? Is it possible that my cat is in the process of failing but it's just taking a long time to do so?
The noise sounds a too harsh/sharp to be the typical exhaust popping.
Any ideas?
stupid cat!
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stiinc
Dodge Dakota
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9/09/2004
19:38:46
| RE: Whats up with dakotas Cat?
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Mine rattled for about a year, It got so bad I was embarassed to go through a drive up window. I got It changed before it plugged up though.
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Ted
Dodge Dakota
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9/10/2004
10:54:55
| RE: Whats up with dakotas Cat?
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Message:
Cats need to be up to a certain temperature to work effectively. The precats are low thermal mass cats that are mounted as close to the manifold as possible. This way they heat up quickly to reduce emissions on cold starts.
The main cat has higher thermal mass so that is will stay hot even during idle periods. This is what does most of the cleanup while you are driving.
Ted
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01Motorsport
Dodge Dakota
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9/10/2004
21:44:32
| RE: Whats up with dakotas Cat?
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I looked underneath a 2004 4.7 Dak at a dealer recently, and was surprised at the size of the pre-cats now; about three times larger than in 2001.
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spt
Dodge Dakota
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9/11/2004
14:49:07
| RE: Whats up with dakotas Cat?
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Message:
Hey mrman my 88 dak has a similar problem to yours and has been doing it for as long as I can remember(at least 3 years), but only makes the rattling noise when down shifting. If the cat was going I thought it would be gone by now, I have no restriction in the exhaust system. I am wondering if the air pump might have something to do with the noise?
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