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SMOG issue....UPDATE !! IT just PASSED!
Posted By: Kern Dog
SMOG issue....UPDATE !! IT just PASSED! - 05/18/12 07:25 AM
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
Posted By: Dean_Kuzluzski
Re: SMOG issue.... who knows any tricks? - 05/18/12 01:01 PM
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.
Posted By: Dcuda69
Re: SMOG issue.... who knows any tricks? - 05/18/12 01:26 PM
If you list all the test results/numbers it will help. High HC is unburned fuel. Lean miss, ign misfire, rich fuel mix, etc. All the numbers may help us help you.
List the limits/max allowable also.
Posted By: buildanother
Re: SMOG issue.... who knows any tricks? - 05/18/12 01:55 PM
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.
Posted By: Pacnorthcuda
Re: SMOG issue.... who knows any tricks? - 05/18/12 03:01 PM
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.
Posted By: RUNCHARGER
Re: SMOG issue.... who knows any tricks? - 05/18/12 03:06 PM
Add some methyl hydrate to the fuel.
Sheldon
Posted By: bbodybill
Re: SMOG issue.... who knows any tricks? - 05/18/12 03:47 PM
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... 
Posted By: rp23g7
Re: SMOG issue.... who knows any tricks? - 05/18/12 03:49 PM
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?
Posted By: blown340
Re: SMOG issue.... who knows any tricks? - 05/18/12 04:58 PM
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
Posted By: topside
Re: SMOG issue.... who knows any tricks? - 05/18/12 05:23 PM
There used to be a guy in SF (since retired) who'd get my 383 RR to pass (with the MP 284/484 cam no less): if the tune-up was fresh, he'd raise the idle speed, pull timing out, lean the idle screws, and get the motor HOT (210-220). Motor was not happy with that but it would pass with room to spare, and I'd just reset everything later. IIRC, same deal on the Hemi car.
Posted By: herkamer
Re: SMOG issue.... who knows any tricks? - 05/18/12 05:34 PM
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.
Posted By: RodStRace
Re: SMOG issue.... who knows any tricks? - 05/18/12 05:42 PM
Greg, yes, it's all a guess. It's often a best guess, but it is still a guess.
The average guy sees 5-10 cars a day. They are anything from a 6 year old low miles creampuff to some old POS. Try to figure out EXACTLY what is causing a misfire on each and every one of them without any work! CO (Rich) is fairly easy in comparison, but any of a hundred things can cause a miss.
Could you be able to tell which houses had plumbing issues AND be able to tell the owner what they are and how much it will cost just by walking thru it for 10 minutes?
Posted By: Kern Dog
Re: SMOG issue.... who knows any tricks? - 05/18/12 07:37 PM
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.
Posted By: DARTH V8Я
Re: SMOG issue.... who knows any tricks? - 05/18/12 08:34 PM
Did you change the metering rods on the TQ? If not, make sure the M-rod 'tree' is not hanging up after acceleration. Also, make sure theres enough vacuume to bring the 'tree' all the way down at idle.
Posted By: Kern Dog
Re: SMOG issue.... who knows any tricks? - 05/18/12 09:17 PM
The carburetor is as it was when I bought the truck last September. I've rebuilt Holleys, but never a T-quad. A buddy had one rebuilt locally several years ago. It ran fine, but I don't know if it was smog compliant since the car was exempt from testing.
There lies the problem: For me, I can't determine if a carb is compliant or not. Mine idles very smoothe and produces no smoke.
Posted By: RodStRace
Re: SMOG issue.... who knows any tricks? - 05/18/12 09:54 PM
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! 
Posted By: Dcuda69
Re: SMOG issue.... who knows any tricks? - 05/19/12 12:34 AM
300 max 1003 measured HC
3.00 max .16 measured CO
If this is right(I copied pasted)It almost looks like a lean miss. With no cats I would expect CO a little higher(maybe 1-2%)1000 HC is a misfire almost for sure. Absolutely sure there's no vac leak? How about a cylinder power balance to make they're all firing? I know you said it runs smooth but 1000 HC is real high cats or no cats!! Just throwing ideas out.
Posted By: Kern Dog
Re: SMOG issue.... who knows any tricks? - 05/19/12 07:32 AM
Lean miss at idle. Highest vacuum at idle... Coincidence?
I guess I'll look closer for vacuum leaks.
My point about the smog techs was written from frustration. When they make incorrect suggestions that cost customers MORE time and money, it just sucks. If the man would've said... "For an hours labor I'll probably be able to determine what it needs." I would have been okay with it. I agree that nobody should work for free. NO arguement there. maybe it is a matter of ME being an eternal optimist. I hear the man say... vacuum leak and I think that is all there is to it. A pessimistic man would always expect the worst.
Posted By: CSK
Re: SMOG issue.... who knows any tricks? - 05/19/12 03:43 PM
the only way to make it pass is with a 4 gas system & make idle speed,mixture screw adjustments while noting changes
Posted By: Geezer
Re: SMOG issue.... who knows any tricks? - 05/19/12 04:02 PM
In the late 90's the highest emissions failure rate in Colorado were Chrysler 440 engines,years 76-78.On a more cheerful note for the roller test it was 82-91 360 Grand cherokees.
Posted By: Kern Dog
Re: SMOG issue.... who knows any tricks? - 05/19/12 04:42 PM
Quote:
the only way to make it pass is with a 4 gas system & make idle speed,mixture screw adjustments while noting changes
This is a new one. 4 Gas system?
I would think that with the 2500 rpm test beating the max limits by a long shot, that I should be able to get the idle numbers down. Maybe I'll visit the smog guys on Monday, or look for one of the few remaining "No pass, No pay" shops.
Posted By: None2Slow
Re: SMOG issue.... who knows any tricks? - 05/19/12 09:02 PM
My brother is a tech in Sacramento. He is a test only shop. How many times have you worked on an engine trying to figure out a problem, and been wrong, only to find out it was something else after buying parts? Dead battery so you buy a new 1 only to find out that the alt was dead, or the regulator or the plug. There not there to fix your car, but to give you ideas. In fact, they are not really supposed to give you advise just for this reason. Ill give my brother a buzz real quick and see what he says to try, but he has always said that even some of the worst cars can pass with just a new cat. Only the cat may last 100 miles before dying due to problems that are causing the car to not pass to begin with.
Posted By: Dakota_Don
Re: SMOG issue.... who knows any tricks? - 05/19/12 09:13 PM
try to fix it first.. but if you run it to about 1/4 tank and add 1-2 gal of methanol to the tank it will clean it up a bit, a lot a bit.. if you ad meth and its really runs bad add a tad more gas.. then after smog test fill er up
Posted By: Supercuda
Re: SMOG issue.... who knows any tricks? - 05/19/12 09:59 PM
Quote:
try to fix it first.. but if you run it to about 1/4 tank and add 1-2 gal of methanol to the tank it will clean it up a bit, a lot a bit.. if you ad meth and its really runs bad add a tad more gas.. then after smog test fill er up
You put that much Methanol in the tank and you can forget about a carb.
METHANOL is very corrosive.
Posted By: Dakota_Don
Re: SMOG issue.... who knows any tricks? - 05/19/12 10:06 PM
not really, ur only adding a lil bit.. done it many times before on carb engines.. u are only adding a gal or so mayb less then your fillng it up after u test.. but also like i said fix it first.. then as a last resort do the meth trick.. i know in some states you dont pass the smog u cant drive it then no ride to work.. so if all else fails use the meth... actully 1/2 gall will clean it up pretty good.. did this on my 74 van many yrs ago.. had carb issues.. no money and no job. had to do what i had to do..van is still runing same fuel system, no problems.. i did fix the carb tho, same fuel lines.. my local NAPA gave me this trick and the meth
Posted By: Sinitro
Re: SMOG issue.... who knows any tricks? - 05/20/12 03:57 AM
As you troubleshoot it..
Find a friendly smog guy who will do a pretest..
If you keep going back and failing the car will be assigned as a
Gross Polluter..Just my $0.02..
Posted By: CYACOP
Re: SMOG issue.... who knows any tricks? - 05/20/12 04:10 AM
Move to a normal state. The truck is 34 years old .
Posted By: Kern Dog
Re: SMOG issue.... who knows any tricks? - 05/20/12 04:35 AM
Yeah... THAT was helpful.
Posted By: Pale_Roader
Re: SMOG issue.... who knows any tricks? - 05/20/12 07:02 AM
Quote:
Yeah... THAT was helpful.
Yeah, but true. We're almost as bad as California and i really do hate it here...
First off, there are a few shops around here that will test you for $5-10 as often as you want. They dont have every single number you may need, but you can at least know when you're wasting your time. I've used one here several times for this exact reason, probably saved me a lot ov money.
Second, you didn't answer a question above: Did that truck come with cats? If it did, you're kinda pissing up a tree trying to make to pass without. Run a different exhaust for emission tests... on a truck it could literally be a 4ft long one-piece off the engine, into one big cat and out the side... on and off in minutes.
Third. Always crank up the idle to absolute max. Ours here is 1150RPM. Any more at idle and they wont test it. I see some guys having trouble idling in there at 600, which to me at least seems like unnecessarily hamstringing yourself. Put something in the tank, like many here have offered, along with 94 octane from the pump, and make damn sure ALL your older gas is out ov there, if you have any. Tune it lean. The 210 thermo is a neat trick, might have to try that one.
I'm definitely no expert on this stuff... but i've passed some serious junk through ours over the years. Some places wont test you (on the rollers at least) if you have studded tires. Hmmm...
I'll be dealing with my own emissions demons soon enough... trying to decide whether to install my fat stinky cam in the engine before i dump it in the car. It'll vastly save me grief installing and breaking in a cam in the car, only to replace them with emissions grief trying to 'tune' it through...
Posted By: Kern Dog
Re: SMOG issue.... who knows any tricks? - 05/20/12 11:29 PM
The truck is equipped with the FEDERAL emissions package. No catalytic converters, no smog pump, EGR or thermostatic air cleaner. Pretty basic stuff.
I like the idea of running the additives and cranking up the idle some. Thanks for the suggestions!
Posted By: Kern Dog
Re: SMOG issue.... who knows any tricks? - 05/23/12 12:39 AM
Quote:
300 max 1003 measured HC
3.00 max .16 measured CO
If this is right(I copied pasted)It almost looks like a lean miss. That IS what the smog guy thought it could be With no cats I would expect CO a little higher(maybe 1-2%)1000 HC is a misfire almost for sure. Absolutely sure there's no vac leak? I just bought a propane can to try. Tha carb cleaner runs out too fast! How about a cylinder power balance to make they're all firing? I know you said it runs smooth but 1000 HC is real high cats or no cats!! Just throwing ideas out.
A few more bits:
I asked about using methanol or rubbbing alcohol. He said that this trick only works in vehicles with catalytic converters, since it heats up the cats and they work harder. I can't legally weld in a pair of cats since the vehicle wasn't originally fitted with them.
Higher idle? He said that the upper limit is around 850. I'll try to get near there. I bought a set of plug wires, a cap and rotor and an intake valley pan. Hopefully tomorrow I'll have some good news.
Thanks to all for the suggestions! Greg
Posted By: Kern Dog
Re: SMOG issue....UPDATE !! IT just PASSED! - 05/23/12 07:24 PM
The Trail Duster JUST passed the smog test!
I think that after the 2nd test, it became clear that it may have had excessive idle HC numbers because the engine wasn't as warm as it was during the first test.
Test#1:
1:11 PM
Idle rpm 674
HC PPM 300 MAX
HC PPM 651 measured
2500 2585
HC PPM 350 MAX
HC PPM 36 measured
Test #2
9:20 AM
Idle RPM 862
HC PPM 300 MAX
HC PPM 1003 measured
The differences between the two tests? I replaced 2 vacuum lines, checked for leaks, replaced the carb base gasket, removed a vac line to the inop cruise control and raised the idle speed, PLUS the engine was a little cooler.
Yesterday I talked with the tech again and he suggested trying another carburetor or new plug wires. At home I DID replace the cap, rotor, plug wires AND add 1 1/2 gallons on E85. I raised the idle and backed out the idle mixture screws 1/2 turn. here are the numbers:
Idle 974
HC PPM 300 MAX,
HC PPM 28 measured !!
2500
HC PPM 350 MAX
HC PPM 49 measured!
FANTASTIC! As always though, I'm curious as to what made the difference. I remember the guideline : "Do only one change at a time."
In this case, I had to play it safe. I was lucky to find a NO PASS, NO PAY smog shop nearby. I suppose that I'll just keep a record of what I did for the next time. Thanks for the suggestions, Greg
Posted By: RodStRace
Re: SMOG issue....UPDATE !! IT just PASSED! - 05/23/12 08:23 PM
Post the CO numbers too. Sounds like it had a lean miss due to the idle mix screws being too far in, but without those numbers it's just a guess.
Posted By: Kern Dog
Re: SMOG issue....UPDATE !! IT just PASSED! - 05/23/12 08:45 PM
Thanks... here we go:
Test # 1
CO %
Idle 674 rpm
3.00 MAX, .24 measured
2500 2585
3.50 MAX, .07 measured
Test # 2
CO %
Idle 862 rpm
3.00 Max, .16 measured
2500 2478
3.50 MAX, .05 measured
Test # 3
Idle 974 rpm
3.00 MAX, .55 measured
2500 2535
3.50 MAX, .08 measured
It runs smoother now than before. I'll probably lower the idle a little though. No dieseling on shutoff.
Posted By: Jim_Lusk
Re: SMOG issue....UPDATE !! IT just PASSED! - 05/23/12 09:57 PM
I'm not a smog expert, BUT it is clear that when you raised the idle you went sufficiently off the idle circuit and into the cruise circuit, indicating that the problem is in the carb idle circuit and one of the big reasons that I sold my '79 late last year and replaced it with the Durango (let the computer adjust things properly - or at least better than I can). Nothing against carburetors, just against carbs that have to pass smog....and not a judgement on you for having that truck, just what works for me.
Posted By: Kern Dog
Re: SMOG issue....UPDATE !! IT just PASSED! - 05/23/12 10:12 PM
Quote:
I'm not a smog expert, BUT it is clear that when you raised the idle you went sufficiently off the idle circuit and into the cruise circuit, indicating that the problem is in the carb idle circuit
I agree there. I also sprayed some carb cleaner down alongside the metering rod passages.
It may be safe to say that a quality rebuild of this carburetor would improve matters without having to resort to any tricks. I've rebuilt Holleys, but these Carter T-quads are a wee bit more complicated!
Posted By: Danan
Re: SMOG issue....UPDATE !! IT just PASSED! - 05/24/12 01:15 AM
When I lived in Sac and had to smog my 79 trailduster, I had a heck of a time with the original worn-out carb. I bushed the shafts, kitted it a dozen times, and still had to cross my fingers with it. I also had to replace my warped/cracked fuel bowl with several junkyard parts that were also warped over the years.
I finally bought a holley spreadbore smog legal carb and I got fantastic driveability and power (compared to the old carb) and never worried about passing smog again. Just an option for next time.
Posted By: bigblock340power
Re: SMOG issue....UPDATE !! IT just PASSED! - 05/24/12 04:19 AM
Greg, what smog shop did you go to? I'll be looking at doing this next year. If it's close to you, that's fine. It'll give the truck a good long time/drive to heat up and be ready for the test. But mine's just a 360 2BBL.
Posted By: Kern Dog
Re: SMOG issue....UPDATE !! IT just PASSED! - 05/24/12 04:41 AM
I went to "Tailpipes" on Greenback lane in Orangevale. I know of another No pass-No pay place on North Antelope in Roseville.
My truck with full time 4wd had to be tested off of the dynomometer. PLUS, I have Federal emissions. Far fewer things to go wrong.
Posted By: MoparMarq
Re: SMOG issue....UPDATE !! IT just PASSED! - 05/24/12 05:51 AM
Congrats on the pass. Reminds me of the few years in the 80s that I had to hassle with getting the RR smogged when I lived in the Bay Area. Got the carb worked on, different air cleaner, aftermarket NOx kit (CA car originally), yada yada. What a goat rope! Finally got tired of doing it and just registered at my sister's house in Bend, OR to avoid the test altogether. Not worth it for a car that was driven MAYBE 1000 miles/year...
Posted By: 70Cuda383
Re: SMOG issue....UPDATE !! IT just PASSED! - 05/24/12 03:15 PM
it's too bad the commies don't have a mileage exemption for collector cars, if you drive less than 2500 miles a year, it should be exempt, and to qualify for the exemption, let them do a $5 or $10 charge for an odometer verification from year to year if they're worried about losing money from fewer tests.
a daily driven 4-banger Honda is going to create more emissions in a year than a weekend cruiser/hobby car.
Posted By: Kern Dog
Re: SMOG issue....UPDATE !! IT just PASSED! - 05/24/12 06:43 PM
That is a good idea.