SMOG issue....UPDATE !! IT just PASSED!
#1235286
05/18/12 03:25 AM
05/18/12 03:25 AM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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My 78 Trail Duster just failed the stringent CA smog test. The truck is all factory correct with 94,000 miles. It is a Federal emissions truck with a GVWR of 6100 lbs. 440, thermoquad, dual exhaust and a 727. Because of the Full Time 4wd, the test consists of a standard sniffer test at idle and at 2500 rpms. The first test it ran well UNDER the allowable limits of HCs at 2500. 360 allowable with 36 showing. At idle it went waaaay over, 600 when 300 was allowable. The tech thought that there could be a vacuum leak or two, so I replaced 2 vac lines and the carb base gasket. I went back, and now it is actually worse! The idle #s went to 1003 and the 2500 rpm test was at 50. What the heck? My experience with smog guys seems to be bad. Whenever I have had a problem, they say..."Uhh, it could be an oxygen sensor"...OR "Ahhh, maybe it is a vacuum leak, or a fouled plug, or a ficklesnort spring." EASY for them to just throw my money around with no regard for my wallet. Are these guys actually trained or do they just guess all of the time? This engine runs smoothe and has no smoke. No unusual odors coming from the exhaust. It has new plugs and oil. It is no hot rod, but it runs well. Would aged plug wires cause a fail at idle but still allow an engine to run so clean at higher rpms? I'm interested in any pointers on what I can do to get this thing to pass. Would a pair of catalytic converters make any differnce in the HC numbers? Any other ideas that I can try? Thanks, Greg
Last edited by Frankenduster; 05/23/12 03:09 PM.
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Re: SMOG issue.... who knows any tricks?
[Re: Kern Dog]
#1235287
05/18/12 09:01 AM
05/18/12 09:01 AM
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Joined: Jan 2003
Posts: 8,940 Holly/MI
Dean_Kuzluzski
master
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master
Joined: Jan 2003
Posts: 8,940
Holly/MI
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Aged plug wires? Unless they are shorting out, they are fine. And you can check that at night in a dark area.
Did that truck come with an EGR and cat. converters when new?? I would think a pair of cats would help.
What about your initial mech. advance timing? More may help combustion efficiency at idle. It would be interesting to hear what other techs might say..........
If you have an EGR, check to see if it works.
R.I.P.- Gary "Coop" Davis 02/09/68-05/13/04
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Re: SMOG issue.... who knows any tricks?
[Re: buildanother]
#1235290
05/18/12 11:01 AM
05/18/12 11:01 AM
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Joined: Nov 2007
Posts: 21,831 Kirkland, Washington
Pacnorthcuda
Too Many Posts
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Too Many Posts
Joined: Nov 2007
Posts: 21,831
Kirkland, Washington
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Quote:
I used to have to retard the initial timing on the 360 2bbls to get them through. The numbers I can't recall right now.
Yep--Pull about 4 degrees out of the intitial timing for one. Also: 1) Remove air filter from the cleaner housing 2) There is an allowable maximum for idle RPM--you want to raise yours so its close. Our max used to be 1200, I would raise the idle to about 1000 and it would clean up nicely compared to 750.
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Re: SMOG issue.... who knows any tricks?
[Re: RUNCHARGER]
#1235292
05/18/12 11:47 AM
05/18/12 11:47 AM
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Joined: Apr 2003
Posts: 228 So. Calif.
bbodybill
enthusiast
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enthusiast
Joined: Apr 2003
Posts: 228
So. Calif.
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Quote:
Add some methyl hydrate to the fuel.
Sheldon
I always add a pint of rubbing alcohol to a half tank of gas, prior to the smog test... Definitely helps...
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Re: SMOG issue.... who knows any tricks?
[Re: bbodybill]
#1235293
05/18/12 11:49 AM
05/18/12 11:49 AM
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Joined: Apr 2010
Posts: 188 Lynnwood Washington
rp23g7
member
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member
Joined: Apr 2010
Posts: 188
Lynnwood Washington
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Quote:
Quote:
Add some methyl hydrate to the fuel.
Sheldon
I always add a pint of rubbing alcohol to a half tank of gas, prior to the smog test... Definitely helps...
What does that do?
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Re: SMOG issue.... who knows any tricks?
[Re: rp23g7]
#1235294
05/18/12 12:58 PM
05/18/12 12:58 PM
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Joined: Aug 2004
Posts: 3,310 Walnut Creek, CA
blown340
master
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master
Joined: Aug 2004
Posts: 3,310
Walnut Creek, CA
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When I used to have to smog my valiant and first challenger in CA I would retard the timing a couple degrees and install a hotter thermostat for the test. They would both fail with the 180 degree stat but pass with a 210. As mentioned above though, definitely start with all maintenance items.
-Jon
70 challenger convertible. 340/5 speed. blown, intercooled, efi, blah blah blah
71 valiant scamp 318/A833OD/AC/PS
00 dakota RC 4.7L 5 spd autoX'r. SRT10/T56 swap in process
73 W200 Power wagon, PTO winch, 4 spd
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Re: SMOG issue.... who knows any tricks?
[Re: topside]
#1235296
05/18/12 01:34 PM
05/18/12 01:34 PM
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Joined: Oct 2005
Posts: 1,305 Lakewood, Colorado
herkamer
pro stock
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pro stock
Joined: Oct 2005
Posts: 1,305
Lakewood, Colorado
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A couple gallons of E85 cleaned up my Ramcharger quite a bit, but not enough to get it to pass. Only missed by about 1/2%. Get to try again this coming week.
Matt 69 Dart Swinger 340 83 W350, Megasquirted with 46RH Old news: 72 Demon street/race mobile Latest: 70 Duster backhalf car and even more
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Re: SMOG issue.... who knows any tricks?
[Re: Kern Dog]
#1235298
05/18/12 03:37 PM
05/18/12 03:37 PM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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First test:
Test RPM %CO2 %02 HC PPM C0 % Idle 674 12.0 3.6 300 max 651 measured 3.0 max .24 measured 2500 2585 13.76 1.3 350 max 36 measured 3.5 max .07 measured
What the heck do I know. It looked pretty good besides the idle HC numbers. After this test, I replaced the vacuum line from the base of the carb to the vacuum advance can. I removed and plugged the vacuum line to the dead cruise control. I replaced the carb base gasket and checked for additional leaks with a can of carb cleaner around the intake ports, all vacuum sources too. I bumped the idle slightly.NO EGR, NO cats, NO thermo air cleaner, NO spark retard, stock dual exhaust. The second test, the truck WAS a little cooler. It was before 9:00 AM.
Test RPM % C02 %02 HC PPM CO2% IDLE 862 11.36 4.4 300 max 1003 measured 3.00 max .16 measured 2500 2478 13.48 2.1 350 max 55 measured 3.50 max .05 measured
Maybe someone can decipher these numbers! Please excuse how close all the numbers appear to be jammed together. I tried to space them apart further but they cram back together! The reason I asked about catalytic converters is that I could weld a pair of high flow cats in CHEAPER than rebuilding or replacing this carburetor.
I don't mean to dump on smog techs, its just that it costs money EACH time they test the thing, and I figured that they were in a better position to diagnose a problem.
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Re: SMOG issue.... who knows any tricks?
[Re: Kern Dog]
#1235301
05/18/12 05:54 PM
05/18/12 05:54 PM
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Joined: Sep 2005
Posts: 12,481 Chino Valley
RodStRace
I Live Here
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I Live Here
Joined: Sep 2005
Posts: 12,481
Chino Valley
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Quote:
I don't mean to dump on smog techs, its just that it costs money EACH time they test the thing, and I figured that they were in a better position to diagnose a problem.
Thanks for that. Try going back to the doc, dentist, store, restaurant, tax man, ANYONE and have them perform the same thing starting all over for free.... You can't even sit through the same movie twice any more!
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