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Author
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Topic: smog check, failed NOx 93 jeep grand cherokee
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66 AC COBRA
Nitrous King
Member # 904
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posted
 
 
my girlfriends 93 grand cherokee Inline 6 failed smog today
it passed hc and co but failed NOx, what would cause this, anything to look for
the cat is not even 2 years old, the plugs, cap, and rotor have 5000 miles maybe
i dont think it is a missfire because the hc and co2 passed fine, NOx was almost double the max allowed
could a o2 sensor cause this, maybe check the egr for operation??
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FFR AC Cobra
72 Vega - WCHRA Extreme 10.5
Posts: 6280 | From: Winters | Registered: Feb 2002
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Blind
2.3L
CAFords OG
Member # 3052
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posted
NOx is usually from the car running too hot
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89 LX Notchback ex 4cyl, 14psi
02 Harley F150, 15psi
Posts: 8521 | From: Fairfield | Registered: Jul 2003
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66 AC COBRA
Nitrous King
Member # 904
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posted
car runs at 195, right where the thermostat opens
I am gonna clean the egr, test the o2 sensor, and put some premium in it and see what i can get out of it on a pre test, fun times ![[Roll Eyes]](rolleyes.gif)
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FFR AC Cobra
72 Vega - WCHRA Extreme 10.5
Posts: 6280 | From: Winters | Registered: Feb 2002
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hidnn.o.s.
¯
Member # 1219
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posted
Eric, isn't one of the "secrets" to passing smog to have 1/4 tank of "87" octane ![[Confused]](confused.gif)
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R.I.P. Willie G. You are missed on this forum
Posts: 15950 | Registered: Apr 2002
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66 AC COBRA
Nitrous King
Member # 904
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posted
maybe if it was an hc or co problem
NOx is a higher than normal combustion temperture, like its running lean or under heavy load
since premium burns slower it burns a little cooler, make sense
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FFR AC Cobra
72 Vega - WCHRA Extreme 10.5
Posts: 6280 | From: Winters | Registered: Feb 2002
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hidnn.o.s.
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Member # 1219
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posted
You are more knowledgeable than I on the subject. Goodluck!
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R.I.P. Willie G. You are missed on this forum
Posts: 15950 | Registered: Apr 2002
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66 AC COBRA
Nitrous King
Member # 904
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posted
quote:
Originally posted by hidnn.o.s.:
You are more knowledgeable than I on the subject. Goodluck!
no, i just like to over rationalize things to make them more complicated and therefore never work ![[Frown]](frown.gif) ![[Big Grin]](biggrin.gif)
i should have drove the thing off a cliff today, i wonder if the insurance company would be suspicious ![[Whoo Whooooo!]](graemlins/woowoo.gif)
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FFR AC Cobra
72 Vega - WCHRA Extreme 10.5
Posts: 6280 | From: Winters | Registered: Feb 2002
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Hungry Hippo
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Member # 537
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posted
i say the egr is clogged or went bad. but i'm just a hippo, i cant even own a car
also, was the cat a quality replacement?
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05 S4 Avant(wagon)
09 C6 H/C/I
Posts: 2959 | From: east bay | Registered: Nov 2001
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92coupe
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Member # 1957
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posted
NOx is made at 2,500F degrees in the CC, just because the cats are new doesnt mean they arent bad. ALL cats now have a NOx bed in them right before the actual catalyst, the bed is designed to cool the NOx down. make sure the car isnt running lean, even try fatting it up just a little. depending on how much time you have a have an actual book from one of my ASE courses, if youwould like i can scan through it and see if i can find anything to help you out. PM me and let me know if you want me too.
Justin
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94-GT BLOWN & STROKED
Posts: 1209 | From: antioch | Registered: Oct 2002
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BCINGUU
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Member # 2397
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posted
Most of the smog equipment on the vehicle (EGR, air pump, etc.) are designed to put NOX back in the chamber for reburning. Check or replace the EGR and check the air pump.
If you were running rich or lean, your HC would be high.
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93 Cobra #4563 347ci 12.0@118 505rwhp 524tq
90 GT "Saleen Cobra" style convertible 347ci
67 GT "Eleanor" style coupe 347ci
Posts: 1425 | From: San Jose, CA | Registered: Jan 2003
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Joooestang66
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Member # 2828
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posted
dont forget to overinflate the tires (if you live in an enhanced area).
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"Don't Drive Faster Than your Guardian Angel Can Fly..... Well My Guardian Angel Can Fly Pretty Fuc*ing Fast!!!"
Posts: 581 | From: Elk Grove | Registered: May 2003
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66 AC COBRA
Nitrous King
Member # 904
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posted
well if it was a mustang cleaning the egr and checking the air pump would be easy
BUT this pos jeep doesnt not have an egr valve, does not have a smog pump, and does appear to have a bad cat
the cat was replaced and sas replaced with a piece of shit cat from who knows where, it is so far down stream i would be surprised if it every got hot enough to work right
so i am putting a new cat on, f**k its expensive for a good one ![[Mad]](mad.gif)
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FFR AC Cobra
72 Vega - WCHRA Extreme 10.5
Posts: 6280 | From: Winters | Registered: Feb 2002
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Don
CAFords OG
Member # 938
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posted
Timming??????? Just a thought
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06 sti 2.5
95 GT 5.2
Posts: 962 | From: Manteca, CA | Registered: Feb 2002
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Hungry Hippo
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Member # 537
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posted
just add another cat closer to the manifold
[ August 30, 2005, 12:03 AM: Message edited by: Hungry Hippo ]
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05 S4 Avant(wagon)
09 C6 H/C/I
Posts: 2959 | From: east bay | Registered: Nov 2001
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66 AC COBRA
Nitrous King
Member # 904
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posted
quote:
Originally posted by Hungry Hippo:
just add another cat closer to the manifold
thats what im going to do homie
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FFR AC Cobra
72 Vega - WCHRA Extreme 10.5
Posts: 6280 | From: Winters | Registered: Feb 2002
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Hungry Hippo
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Member # 537
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posted
thats gonna be clean yo! running clean, that is
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05 S4 Avant(wagon)
09 C6 H/C/I
Posts: 2959 | From: east bay | Registered: Nov 2001
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Jimbo
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Member # 1456
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posted
Hang on, before you go adding cats and stuff like that. Check to make sure fuel pressure is in spec, a clogged fuel filter can cause a lean condition. Also, might want to make sure they had the cooling fan blowing on the front of the Jeep during the test(if outside air temp was over 72 deg during the test they are REQUIRED to have it on). On the printout, check the CO and espically O2 levels, if they are at or near zero the cat is probably fine and you should look elsewhere. If they are higher than that it COULD mean the cat is bad but it could also mean the cat wasnt hot enough during testing. Hope this helps.
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1965 Mustang Coupe
EFI, 302ci, T-5, 3.70's.
Click for My Mustang Pics
Posts: 352 | From: Castro Valley,CA | Registered: Jun 2002
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66 AC COBRA
Nitrous King
Member # 904
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posted
well i put on a nox buster cat, didnt help
timing is spot on, fuel pressure is fine
the only left to do is replace the O2 sensor, run ome sea foam thorugh it to clean the carbon out of the cylinder (lower compression a little)
and thats it, after that the motor is junk, time to roll the fucker off a cliff
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FFR AC Cobra
72 Vega - WCHRA Extreme 10.5
Posts: 6280 | From: Winters | Registered: Feb 2002
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rickm347
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Member # 5323
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posted
put a quart of ATF in the tank then fill it up-you'll pass almost 100%
Posts: 936 | From: Chico | Registered: Feb 2005
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66 AC COBRA
Nitrous King
Member # 904
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posted
quote:
Originally posted by rickm237:
put a quart of ATF in the tank then fill it up-you'll pass almost 100%
this sounds very similar to what sea foam does, cleans the engine out and smokes like crazy for a while
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FFR AC Cobra
72 Vega - WCHRA Extreme 10.5
Posts: 6280 | From: Winters | Registered: Feb 2002
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TRIXSNK
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Member # 2844
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posted
quote:
Originally posted by 66 AC COBRA:
quote:
Originally posted by rickm237:
put a quart of ATF in the tank then fill it up-you'll pass almost 100%
this sounds very similar to what sea foam does, cleans the engine out and smokes like crazy for a while
When i worked at Speedee Oil Change way back when....we used to have a kit that included fuel inj cleaner and some stuff we used via vaccum to clean out the combustion chamber kinda like what you guys were talking about....that and a tune helped a large % of the cars that were borderline.
Then again there were no load based dyno smogs back then
Also some stuff called "clean power" helped some borderline cars as well. It was an additive to the fuel system.
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9 Sec EVO 9 is GONE!
New project in the works.......
Posts: 3740 | From: Bay Area | Registered: May 2003
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