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Steven R.
Dodge Dakota
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8/08/2007
23:25:23
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 Subject: 95 Dakota Failed Smog
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I've been working on my 1995 Dodge Dakota with the 3.9L V6 trying to get it ready for a smog test. Cleaned the IAC motor and now all the trouble codes are clear. Took it in for a smog test today, and it failed. Here are the results:
15MPH - HC (PPM) 49 Measured, 88 Max - CO (%) 0.04 Measured, 0.64 Max - NO (PPM) 572 Measured, 508 Max
25MPH - HC (PPM) 34 Measured, 53 Max - CO (%) 0.03 Measured, 0.77 Max - NO (PPM) 585 Measured, 761 Max
The only place where it failed was NO at 15MPH. Not by much either. The smog tech said run some fuel injector cleaner (I already ran a can of Seafoam through it) and run 91 octane fuel and it will pass.
NO is formed because of high combustion temps, so would one range cooler plugs fix it? (Autolite 3923s right?) Or should I just do the 91 octane and retest?
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Steven R.
Dodge Dakota
JOIN HERE
8/09/2007
01:49:52
|  RE: 95 Dakota Failed Smog
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Picked up the Autolite Platinum AP3923s from Walmart. After a mail in rebate they come out cheaper than the normal 3923s! (which they were out of)
The Platinums should do the trick just the same as the normal plugs, right?
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J and J Auto
GenII
8/09/2007
23:25:20
| RE: 95 Dakota Failed Smog
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Message:
Your 95 has an egr valve that sends exhaust back
threw the intake carriying less fuel it cools the
cylinder temps
Replace your egr and you will pass the test with
flying colors
The o2 sensor will also cause the high emissions
if its running lean the cyl temps will be high
forget the autolite get a set of NGK FR5 Vpower
plugs this is 1 colder gap at .035 and you will
notice the diff in the way it runs
Larry
J&J Auto
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?
Dodge Dakota
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8/15/2007
13:00:21
| RE: 95 Dakota Failed Smog
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Or . you might need a new cat.
How old is the one on there now ?
If original = probable need to replace.
If an aftermarket one is on there and over two years old = probably need replace.
Will reduce all of your 'numbers'...
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Bob Lincoln
Dodge Dakota
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8/16/2007
08:57:35
| RE: 95 Dakota Failed Smog
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If the cat were bad, the HC numbers would not be so good. If the EGR replacement doesn't help, look at your radiator's cooling fins to see if they're disintegrating. That pushed me over the NOx limit. And check thermostat.
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Steven R.
Dodge Dakota
JOIN HERE
8/17/2007
02:39:48
| RE: 95 Dakota Failed Smog
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Well, it passed. I replaced some little stuff like the breather filter and PCV valve, checked the EGR valve (which appeared to be working fine) and reinstalled it with a new gasket and put in the Autolite AP3923 plugs. I went to a different place and they ran it at a higher RPM and it passed.
So I'm free and clear for another two years, but hopefully it isn't anything too major. The truck needs the timing set replaced, so it is going to get fresh coolant and I can check the radiator and thermostat while the truck is apart.
The cat I believe is original, so it may need replacement, but I was told that even though the EGR seemed to be working fine, it may be partially clogged and giving the high NO numbers.
I figure next time the truck needs to be smogged, it will have a new timing set and I will replace the EGR valve and then smog it. If it doesn't pass, then I'll worry about a new cat.
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Bob Lincoln
Dodge Dakota
JOIN HERE
8/17/2007
08:43:53
| RE: 95 Dakota Failed Smog
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Valve timing slop can affect NOx readings, so that alone may bring it down.
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