My Dakota failed emissions....$650.00 later, I'm legal again
#2196995
11/15/16 10:08 PM
11/15/16 10:08 PM
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Joined: Jan 2003
Posts: 16,838 Between Houston & Galveston TX
SattyNoCar
OP
Smarter than no class Flappergass by a mile
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OP
Smarter than no class Flappergass by a mile
Joined: Jan 2003
Posts: 16,838
Between Houston & Galveston TX
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(Posting here since this section gets more traffic than the truck section) Took my Dakota in for its annual smog test, and it failed the Low Speed NOx. Am I wrong to think that if it was the catalytic convertor more readings would be out of spec? I'm leaning towards the EGR, but that's just a guess. When I had the intake off (last year), I cleaned the EGR and the port out as much as possible, but, did not test or replace the EGR. Plugs, cap, coil were all replaced spring of 2015. Truck other wise runs fine. Here's the link to the test results: Results Oh, this is my '93 Dakota with 3.9 and 168K miles... Suggestions? Thanks.
John
The dream is dead, long live the dream.......😥
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Re: My Dakota failed emissions, but, not by much........
[Re: Challenger 1]
#2197024
11/15/16 10:51 PM
11/15/16 10:51 PM
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Joined: Jan 2003
Posts: 16,838 Between Houston & Galveston TX
SattyNoCar
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Smarter than no class Flappergass by a mile
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OP
Smarter than no class Flappergass by a mile
Joined: Jan 2003
Posts: 16,838
Between Houston & Galveston TX
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I spent the morning running errands, ran it around town, 20 miles down the freeway and back, and then when I got to the station, they took the truck right in, so there was no cool off period.
And, it was about 80 degrees out when I took it in.....
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Re: My Dakota failed emissions, but, not by much........
[Re: SattyNoCar]
#2197253
11/16/16 10:19 AM
11/16/16 10:19 AM
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Joined: Nov 2003
Posts: 10,228 Colleyville
3hundred
I Live Here
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I Live Here
Joined: Nov 2003
Posts: 10,228
Colleyville
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My wife's '93 Ramcharger had problems just like yours nearly every year. Every time it was the cheap muffler shop cat was shot. The last one we had installed was at a real shop with the correct Walker cat con. It was about twice the size of the cheapy univeral muffler shop junk. Once, several years ago, we thought it was the EGR, replaced it, we were wrong, only last year did it really need replaced.
Robert
'68 Fury Convertible '69 300 Convertible '15 Durango 5.7 Hemi '16 300 S Hemi
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Re: My Dakota failed emissions, but, not by much........
[Re: SattyNoCar]
#2197270
11/16/16 11:28 AM
11/16/16 11:28 AM
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Joined: Feb 2010
Posts: 1,645 Phila. Pa.
Mattax
top fuel
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top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
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If there was no cat, the answer would be to lean out the idle and idle. A little readjustment of the idle mixture screws and maybe the throttle opening (idle speed). But the cat is also a possibility and to a lesser degree the EGR. IIRC, the early catalytic converters were mainly to reduce the NOx. The other emmissions were controlled by running higher idle temperature (leaner, combined with an idle stop solenoid so it won't diesel on shut down). Your '93 probably came with a 3-way cat which was designed to help reduce all the bad stuff, but again IIRC NOx reduction is the main job of the cat. So, if you fiddle with the idle-off idle, bring them to the specs on the hood sticker (if that's option on a '93) that could squeak it by. The EGR valve operation should be testable with a vacuum gage and pump. If the EGR exhaust gas passages are partly plugged up - that's harder to do anything about. You can access the valve orifice but thats about it without a teardown. EGR systems usually have temperature and vacuum switches Off the top of my head there is no EGR until coolant reaches a certain temperatures, no EGR at WOT, etc. If you want to read more about diagnosing exhaust for relatively modern cars there was a Toyota (ASE?) pdf online in various locations. This may be it here: http://www.readbag.com/autoshop101-forms-h56
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Re: My Dakota failed emissions, but, not by much........
[Re: Mattax]
#2197280
11/16/16 11:56 AM
11/16/16 11:56 AM
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Joined: Jan 2003
Posts: 16,838 Between Houston & Galveston TX
SattyNoCar
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Smarter than no class Flappergass by a mile
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OP
Smarter than no class Flappergass by a mile
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The catalytic convertor that's on there is of unknown origin and age. When I bought the truck, the exhaust consisted of the original cat, a newer cat back where the muffler should have been, then a stupid little 'race' muffler not 6 inches off the back of the second cat. When I had a new muffler installed, they took the second cat and replaced the stock one with it (the truck only has one cat now in the stock location). There was a VERY noticeable difference in how the truck ran after doing this. As for pinging, it hasn't pinged at all since I did the plenum and intake gasket (and when it did, it was only slight). I'm going to get after it in a few minutes......
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Re: My Dakota failed emissions, but, not by much........
[Re: SattyNoCar]
#2197318
11/16/16 01:17 PM
11/16/16 01:17 PM
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Joined: Jan 2003
Posts: 16,838 Between Houston & Galveston TX
SattyNoCar
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Smarter than no class Flappergass by a mile
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Smarter than no class Flappergass by a mile
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Well, got the EGR off. Still just as clear as when I cleaned it. Not sure how the electrical connection plays into it, but, lacking a vacuum pump, I gave it a suck with my mouth. No resistance. Being no resistance, I carefully blew into it, and felt air coming out from the diaphragm. That's not good, is it?
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Re: My Dakota failed emissions, but, not by much........
[Re: SattyNoCar]
#2197375
11/16/16 03:57 PM
11/16/16 03:57 PM
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Joined: Nov 2005
Posts: 253 Pasadena, Texas
fal3
enthusiast
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enthusiast
Joined: Nov 2005
Posts: 253
Pasadena, Texas
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Had a '90 Dakota w/ 3.9 w/120,000 miles that failed inspection. Took EGR off, cleaned it, truck passed. The following year, truck failed b/c of EGR. Took it off, cleaned it; truck still failed. Replaced EGR and truck passed. Sometimes the cleaning helps, but only to a certain extent.
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Re: My Dakota failed emissions, but, not by much........
[Re: fal3]
#2197484
11/16/16 07:03 PM
11/16/16 07:03 PM
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Joined: Jan 2003
Posts: 16,838 Between Houston & Galveston TX
SattyNoCar
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Smarter than no class Flappergass by a mile
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Smarter than no class Flappergass by a mile
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Replaced the EGR this morning. It made a noticeable difference with how the truck runs and sounds. Drove all over this morning running errands, took it even further on the freeway, then took it back for another test. Too soon? It failed NOx by a much larger number this time. Grrrr......
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Re: My Dakota failed emissions, but, not by much........
[Re: SattyNoCar]
#2197584
11/16/16 10:28 PM
11/16/16 10:28 PM
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Joined: Oct 2005
Posts: 4,956 WI
Dcuda69
master
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master
Joined: Oct 2005
Posts: 4,956
WI
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A scan tool would be helpful to look at engine data. Ensure the engine is in closed loop fuel control,O2 sensor is functioning properly,fuel trim data is in range,coolant temp is correct,etc. NOx is created by combustion chamber heat.....anything that could cause combustion chamber temps to go up will increase NOx production. EGR is designed to reduce those temps...just because it's new doesn't mean it's working correctly. Lastly the reduction portion of the 3-way cat is designed to reduce NOx at the tailpipe.
Last edited by Dcuda69; 11/16/16 10:29 PM.
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Re: My Dakota failed emissions, but, not by much........
[Re: Skeptic]
#2197717
11/17/16 12:39 AM
11/17/16 12:39 AM
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Joined: Jan 2003
Posts: 16,838 Between Houston & Galveston TX
SattyNoCar
OP
Smarter than no class Flappergass by a mile
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Smarter than no class Flappergass by a mile
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I'm not 100% at this point, but, I think the original O2 sensor is still in there. I ran out of daylight before I could find the plug end. I'm disappointed about the results of the EGR even more so because of how much better the truck is running. Even the inspection guy made a comment of how it sounded different when I pulled up to his shop. Are Bosch sensors that bad? It's all I have readily available without ordering. I can't do anymore until Saturday. Thanks for the replies!
John
The dream is dead, long live the dream.......😥
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Re: My Dakota failed emissions, but, not by much........
[Re: SattyNoCar]
#2197776
11/17/16 02:13 AM
11/17/16 02:13 AM
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Joined: Jan 2003
Posts: 4,395 The Pale Blue Dot
Skeptic
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master
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Posts: 4,395
The Pale Blue Dot
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I'm not 100% at this point, but, I think the original O2 sensor is still in there. I ran out of daylight before I could find the plug end. I'm disappointed about the results of the EGR even more so because of how much better the truck is running. Even the inspection guy made a comment of how it sounded different when I pulled up to his shop. Are Bosch sensors that bad? It's all I have readily available without ordering. I can't do anymore until Saturday. Thanks for the replies! If it's just a matter of a day or 2 I'd order one. I got rid of all my personal OBD1 stuff years ago, no $$ in it, even where I work we have just about gotten rid of all those- I work for a school district,and the 20+ year old stuff is HD or diesel, so no diagnostics. Finding guys that are proficient in those old systems is getting tough, we are all retiring or getting out of it, I've got another decade min, if my body can hold up.
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