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Dyber
Dodge Dakota
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4/28/2004
18:19:03
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 Subject: High NOx (failed Cal. smog)
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I have a '91 Dodge Dakota V6 3.9...
I failed California smog recently with high NOx readings. I know the EGR system wasn't operating for quite awhile and, despite changing the valve and transducer last year, I believe the EGR passages are clogged with carbon. I'm wondering if I'll need to remove the intake manifold or will I be able to clean the passages by simply removing the throttle body?
Speaking of the throttle body, I'd noticed in the shop manual that relieving fuel pressure is needed before removal. The method of inducing current into a certain terminal on the injector connection didn't seem to work for me. Would it be O.K. to allow the truck to sit for awhile to relieve pressure, or should I continue to try and relieve it per the manual method?
Any advice would be most appreciated!
Don
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another mark
Dodge Dakota
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4/29/2004
00:49:00
| RE: High NOx (failed Cal. smog)
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I recently replaced my injectors and the recommended method in the shop manual was to pull the fuel pump relay and remove the gas cap. Start the truck and when it dies the fuel pressure has been relieved. I parked my truck overnight with the gas cap off and that alone seemed to do the trick. When I removed the fuel rail there was very little gas left just drops at each injector.
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?
Dodge Dakota
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4/30/2004
08:43:29
| RE: High NOx (failed Cal. smog)
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Clogging may be more in the tube that comes out
of pass side exhaust up to EGR..
Or right at that point where it comes out of
the exhaust manifold - this is where it has the
smallest passageway, I would inspect this first
before pulling intake........
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Dyber
Dodge Dakota
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4/30/2004
15:54:12
|  RE: High NOx (failed Cal. smog)
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I wasn't aware of that tube. Obviously I need to look at this situation more carefully. I've got a temporary sticker good 'til 6/15, so naturally it's proven to be a perfect excuse to procrastinate while praying for this thread to develop.
Does the information about the tube apply to a '91 Dakota V6 3.9? I'd assumed that the passage from the exhaust manifold was an internal
bore of some kind mating with the intake manifold, unable to be accessed without removing the intake.
Boy you may have saved me a real headache. I'll look into this as soon as I get home.
Thank you again,
Don
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Bob Lincoln
Dodge Dakota
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5/02/2004
10:04:18
| RE: High NOx (failed Cal. smog)
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Probably the same as a 92, which has an external tube. Stand on the passenger side, look behind the air intake at the EGR, you can follow the tube to the exhaust manifold.
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Dyber
Dodge Dakota
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5/03/2004
16:32:39
| RE: High NOx (failed Cal. smog)
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It's just my luck there's no external tubes on the exhaust manifold (except the air injection tubes). Does this mean it's internally bored in the exhaust manifold, leading through the head to the egr valve? This bit of information has been hard to get no matter where I look.
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Bob Lincoln
Dodge Dakota
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5/04/2004
12:32:57
| RE: High NOx (failed Cal. smog)
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Larry posted a picture of such an intake manifold awhile back, unidentified year and engine. Could be a passage there.
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Dyber
Dodge Dakota
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5/04/2004
17:14:54
| RE: High NOx (failed Cal. smog)
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So I guess it's looking more likely I'll be forced into removing the intake to clean this this passage. I still don't quite understand how the passage from the exhaust is mated with the intake, unless it goes through the heads.
Don
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?
Dodge Dakota
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5/05/2004
09:14:02
| RE: High NOx (failed Cal. smog)
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Message:
I Don't think that is an ( Air injection tube )
You don't have an AIR pump ??
That tube should be the EGR line........
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Dyber
Dodge Dakota
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5/05/2004
14:25:19
| RE: High NOx (failed Cal. smog)
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Message:
The tube(s) in question are connected to the air pump. Although it's really only one tube, it branches off into two tubes for the two exhaust manifolds.
In order to figure out what it is, I looked in the manual for instructions on removing the exhaust manifold and one of the steps was 'remove the air injection tube if equipped'. Since this tube(s) is/are connected to the air pump, I figured it had to be the air injection tube.
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