Emissions gurus - I seek your advice ***UPDATED***

[Panoscopic]

I just got back from a failed emissions test:

HC Standard - 174 Reading 244

CO Standard - 1.56 Reading 7.80

Whats upsetting is that last year it passed with flying colors and I've only driven it 300 miles since then.

I've also done a lot of work, and its running the best it ever has. I've put in a new powervalve and replaced a leaking PCV hose. I also repaced a hose that was mysteriously re-routed. The vacuum advance had gone directly to the ported vacuum, and I re-installed according to the factory schematic that has it going to the CTO and put the ported vacuum back into the system. I adjusted the idle mixture with the "close it until it stumbles then back off 1 turn" technique.

Any ideas of where I sould start in my diagnosis?

[ March 24, 2004, 01:59 PM: Message edited by: Panoscopic ]

[Matthew W. Woodruff]

FWIW, I am struggling with the same issue and had a bad vac advance on the distributor; replaced the dizzy last weekend with a DUI unit and am going back to the inspector next week. Vac advance is literally the last place I looked.

[Panoscopic]

How important is advance to emmissions levels? I had also back off the advance - it was at something like 20deg.

[jode]

I love my 76…have never failed emissions – even with NO vac advance at all :D

[Damage, Inc.]

Ignition

[The Anti-Chrysler]

Make sure the engine is running hot enough - that's one reason they use a 195 degreet thermostat - it allows a leaner mixture. Also, check and make sure your timing is right on. Too much advance will create too much NoX from what I recall. Is it the original converter on the truck??? A new converter may take care of all of your problems, if the engine is otherwise running great.

[89grand]

Originally posted by Panoscopic:
How important is advance to emmissions levels? I had also back off the advance - it was at something like 20deg.20 degrees sounds like way to much. I would start with about half that much and go from there.

[ March 10, 2004, 04:31 PM: Message edited by: 89grand ]

[DjD]

You can check here.

http://www.recarbco.com/technical/smog/smoginfo.html#7

[Panoscopic]

Originally posted by 89grand:
</font><blockquote>quote:</font><hr />Originally posted by Panoscopic:
How important is advance to emmissions levels? I had also back off the advance - it was at something like 20deg.20 degrees sounds like way to much. I would start with about half that much and go from there.</font>[/QUOTE]Thats what I did - I backed it down before the test.

It might have been a mistake - seems that more advance equals cleaner burn.

[ March 10, 2004, 05:30 PM: Message edited by: Panoscopic ]

[andy d]

too much CO is carburation too rich . i have the same problems. please post your results. im about to get a napa rebuild kit for the 2150

[Panoscopic]

Originally posted by andy d:
too much CO is carburation too rich . i have the same problems. please post your results. im about to get a napa rebuild kit for the 2150The carb was rebuilt about 1,000 miles ago. Last year (300 miles ago) the test results were perfect. I would sure hope a rebuild lasts longer than that!

[SBJeep]

I haven't heard the 1 turn technique. Mine needs to be leaned out just to pass. It idles a little rough at this point. After the test, I back out the mixture only 1/4 to 1/3 turn to smooth out the idle. 1 turn sounds like it may be too much.

[carrotman]

Yes. Use a vacuum gauge and back out each mixture screw 1/8 to 1/4 turn after vacuum starts to drop.

[Panoscopic]

Let me make sure - turning in is to lean the mixture, out is rich? When I adjust it, the vacuum (manifold) really does not change that much.

[The Anti-Chrysler]

Originally posted by Panoscopic:
Let me make sure - turning in is to lean the mixture, out is rich? When I adjust it, the vacuum (manifold) really does not change that much.Turning in is leaning the mixture. I'll bring up the converter again. It doesn't matter how great the engine is running if the converter is shot. It doesn't take long at all for a poorly running engine to destroy a converter.

[snafubrian]

hey, if you go to the meet at bass pro and you can wait that long, we have some stuff here at the dealer i can let you try. it does wonders for the emission test. and ive seen a lot worse pass after using this stuff. i would say the problem is more with not driving than a problem with truck. i would take this thing out on highway for 50 to 60 miles, and romp on it to blow all the build up out. just a thought, but let me know and i will get you that cleaner to try. im in grand prairie, not far from you, so if you cant wait i can probably meet you somewhere this weekend or something.

brian

[DjD]

My carb. adjust. screws aren't even out a full turn normally. I put them about 1/2 turn out for inspection, just barely running. But, there is some controversy as to whether the idle screws affect the dyno test, especially numbers as bad as yours; are you sure the vac line to the power valve is connected to manifold vac and not plugged or something?
What are your NOx, CO2 and O2 numbers? Well, I imagine your NOx is almost non-existent running that rich.
New Jersey has a low mileage exemption that they don’t publish anywhere that I could find. I’m sure you want to pass legit, but if you get “down to the wire” there might be a reduced idle test since you drive it so little. I had to speak to the manger of the inspection station to confirm what I had heard.
I think you have a major problem. It might be a simple fix, but I doubt that idle screws or additives will help much.

[DjD]

Another good site:

http://smogsite.com/sample.html#smbk

"Next we need to know what the Smog Machine measures. These are the gases that the 4 or 5-gas smog machine sees:
1 HC: Unburned Gasoline
2 CO: Partially Burned Gasoline
3 CO2: Completely Burned Gasoline
4 O2: Oxygen, the Good Stuff
5 NOx: Oxides of Nitrogen (This is only seen by a 5-gas smog machine)"

[snafubrian]

panascopic, i think that is how you put it, anyways, im not far from you if you want to meet and i'll give you this emission cleaner and run it a few days then bring it back to me i will at least run it on machine for free and not charge you to see if it helped. cheaper than replacing any parts right now.

brian

[J10Mike]

brian, which emission cleaner are you speaking of? i used some last year and it worked. but, i don't recall the brand name.

[snafubrian]

bg product

brian

[J10Mike]

bg product? that's it?

[snafubrian]

just a company name, they are called bg products. awesome stuff. this is not sold over the counter or to individual sales. only through service department. that is why some stuff at napa and such just does not cut it. we have to put in vehicle and run outside this stuff is so potent, but it works like a champ. we ran this stuff through my grandpa's 85 chevy 1/2 ton one day a few years back and it made it pass with flying colors after failing the emission test.

brian

[carrotman]

Those emission products are good if you have a high compression, over-cammed engine. Shouldn't need them on a stock AMC. If adjusting the mixture screws has no effect at idle, gas is coming from some other source like a broken power valve, or the choke is closed. Emission products won't fix that.

[snafubrian]

i dont see how a chevy 305 and an amc 360 would be a whole lot different, but im just offering a free inexpensive cheap idea that i have seen work. for a free try and free testing at a state emisson center i thought it might be worth a try before overhauling carb.

[J10Mike]

carrotman,
this is what happened last year. stock 360 with all the smog equipment fails emissions. mechanic neighbor gives me a bottle of this gas treatment (brand unknown), tells me to fill the tank, and drive on the interstate for about twenty minutes before heading to emissions center....it passes. i threw away the container by accident and i don't recall the brand name. my mechanic neighbor has since moved.

[snafubrian]

maybe i should market this stuff on here, might make some money. lol.

brian

[J10Mike]

maybe you should.

[Panoscopic]

Originally posted by snafubrian:
panascopic, i think that is how you put it, anyways, im not far from you if you want to meet and i'll give you this emission cleaner and run it a few days then bring it back to me i will at least run it on machine for free and not charge you to see if it helped. cheaper than replacing any parts right now.

brianHey, I might take you up on that....I'd like to take care of the problem, but as a "bridge" to get the test....

Oh yea, the inspection station was a little "suspicious". He says for me to leave it there for two hours and his friend will come buy and "fix it" so it will pass for $60....

[ March 11, 2004, 02:37 PM: Message edited by: Panoscopic ]

[DjD]

snafubrian, way to go, nice offer on the free test!
I would pay the $60 if it doesn't pass with Brian's free test.

[Michael]

Hey Brian think you could help out another area fsjer????? I am a mechanic but my shop does not have a dyno/ obdII only and we do not have a 5 gass. Man I would love some help. I have put mine off for about 3 months. I will be willing to pay for your troubles. Or buy lunch or something.

[snafubrian]

michael, yeah, i can help ya. just let me know.

brian

[The Anti-Chrysler]

Originally posted by Panoscopic:
[QUOTE]Oh yea, the inspection station was a little "suspicious". He says for me to leave it there for two hours and his friend will come buy and "fix it" so it will pass for $60....Wow!! :eek: :eek: That's what was happening in CT, and now emissions tests are done at certified garages, where they have retinal scans for the certified testers. No more bribery going on around here....

[snafubrian]

not doing anything illegal here. just a fsjeeper helping another, nothing illegal about running a trial test on the dyno. we do it all the time to see if they will pass, especially on the trade ins. come one come all, just open wallet!! just joking, lol.

brian

[letank]

high HC and high CO... seems like it is too lean... so you have unburned gas ; HC and CO.....

i would but the mixt screw about 1.5 turn,.... this is standard for all FSJ.... i have one with a 2100 and one with the 2150. Especially that you passed last year and only drove 300 miles

the other point could be a blown power valve dumping gas into the manifold..... make sure the power valve is connected to intake manifold... high vacuum, no gas discharge.... low vacuum or none fuel is dumped

as for the distributor... you can or need to measure how much vacuum is going to the distributor at idle..as a little vacuum will advance your timing...... i had a bad CTO and vacuum all the time on the 85.....

cheers

Michel

[Michael]

Brian sounds great. I will email you. Looking forward to it!!!

[Panoscopic]

Originally posted by Michel:
high HC and high CO... seems like it is too lean... so you have unburned gas ; HC and CO.....

i would but the mixt screw about 1.5 turn,.... this is standard for all FSJ.... i have one with a 2100 and one with the 2150. Especially that you passed last year and only drove 300 miles

the other point could be a blown power valve dumping gas into the manifold..... make sure the power valve is connected to intake manifold... high vacuum, no gas discharge.... low vacuum or none fuel is dumped

as for the distributor... you can or need to measure how much vacuum is going to the distributor at idle..as a little vacuum will advance your timing...... i had a bad CTO and vacuum all the time on the 85.....

email direct if you need more help.....

baleam@anesthesia.ucsf.edu

i am swamped with work...

cheers

MichelGreat tips! I'm going to do some diagnosis with my vacuum gauge this weekend. See of all this stuff is really working.

[Panoscopic]

Some follow up....

I checked the timing and is spot on at 12 deg.

The vacuum going to the distributor increases nicely with RPM so its seems to be working.

Powervalve is brand new. Just replaced that and a really shot hose going to the PCV.

It runs the best it has in years. When I floor it, no black smoke of any kind - in fact I can't see any smoke at all.

Idle is still semi-rough, but still acceptable and again the best it has idled in years.

OK, here is a new clue. Vacuum is a little low. About 13-14 in and slowly fluctuates 1-2 in at idle. What does this tell me?

[carrotman]

Slow change of vacuum indicates incorrect idle mixture. Low vacuum indicates incorrect ignition timing (but you said it's correct), incorrect valve timing, incorrect idle mixture, worn piston rings, or vacuum leak.

I would adjust the mixture first, but you could plug every hose coming off the carb and intake and adjust the carb correctly. Keep the vacuum gauge on and connect each hose. The one that causes the vacuum to drop indicates that hose or vacuum motor is leaking.

[Panoscopic]

Well, what is so confusing to me is that when I tested it last year, it was running like crap - complete with a blown power valve and a huge leak in the big PCV hose and yet still passed with ease.

[letank]

for testing you can increase your timing to highest vacuum reading... and decrease idle speed to keep it about 800 - 900 rpm... we are trying to pass smog... so the highest idle speed gives you the best values..... the max allowed is 1000 rpm, but for some reason... if i dial 1000.... once at the test center it reads 1100... so i keep it to the 900....

then enrich your mix.... for the highest vacuum / speed combo..... do it for both screws.... then lean a tad.... you may have to lower the idle as walll to keep in the 800-900 rpm (yes the TSM says 750 or so.....)

as you have the 86 with the TF 727... i would put it in Neutral to help the trany to cool (no oil circulation in park) and choke the wheels back and front so you do not get runover by the waggy, if the lever shift to either Drive or reverse

i have about 2 1/4 on the 74... and about 2 on the 85

Cheers

Michel

[DieselSJ]

300 miles in a year - that means it sat most of the time. You could have gas that has gone bad. Also, if those 300 miles were short trips then the plugs could be fouled. Plus a carb rebuild 1000 miles ago doesn't matter much if it sat for a year.

Alternately, you can do like I did with my CJ and run about a 40% methanol mixture. If you do that, be careful as it will be running EXTREMELY lean. Do it when the tank is almost empty and fill it with gas immediately after the test.

[DieselSJ]

Originally posted by Michel:
high HC and high CO... seems like it is too lean... so you have unburned gas ; HC and CO.....

Don't you mean too rich? Lean is not enough fuel, rich is too much fuel.

[Panoscopic]

Update

Here is what I did:

1) Got a fresh tank of gas
2) Leaned out the idle as far as it would go and still run
3) Ran it out on the highway at 70 mph and got it nice and hot

Still failed miserably! HO bad, and CO over the top. NOX - very clean.

Took it to two mechanics

One who does quick fixes for smog test, said its way too rich - won't touch it when its that bad.

The other mechanic, a very seasoned guy, looked at the numbers and said the cat and ignition are doing a great job trying to keep up with the extra fuel, but way too much is getting dumped. Since the fuel system is a "feedback" type, something is causing the system to go to default, which is full rich.

Aha!! Made me think of he power valve I just replaced.

Got back home, looked under the mess of vac hoses, and saw the manifold vac hose that feeds the power brakes and the CTOs, which ultimately control the power valve, was hanging loose. Arghh. How could I miss that? Hooked that baby right back up and it right away the exhausts smelled "cleaner". Don't know if this is my immagination or what.

If a drop in manifold vacuum causes the power valve to fully open, this would make total sense to explain why the engine was running super rich, yet on full throttle, there was no black smoke since a full open power valve is what it is supposed to be at that point.

Don't know if I should do any more diagnosis before taking it back for a retest, but I think this just might be it!!

[ March 24, 2004, 02:01 PM: Message edited by: Panoscopic ]

[carrotman]

So you were better than those two mechanics. What does you vacuum gauge read with all the hoses hooked up? Now is the time to adjust the mixture.

[Panoscopic]

Vacuum is up to 17 - I think thats normal.

[DjD]

Sounds like you fixed it.
High manifold vacuum is what keeps the power valve closed. At idle, 17, it is closed. When you are driving and hit the throttle kind of hard, manifold vac drops to maybe between 7 and 11 and the first stage of the PV opens. When driving and you stomp on it, wide-open throttle, the manifold vac drops below like 4 and the PV opens all the way. The power valve is not open if you're cruising steadily down the road, because manifold vac is high at the time.
Now your NOx will go up, but if your EGR is working you shouldn’t have any problem.
You have to test it now to see where you stand.

[Panoscopic]

I have to be ready for test - I used my two tests that I get for the $40. Next one is $40 so I better be ready!

[andy d]

PLULEEZE, post your results, i discovered that the vacuum line to the powervalve was off as well. i havent re-tested yet, but the rig runs a lot worse with the vacuum connected, so im guessing the pv is shot. TIA

[Panoscopic]

OK, I took a while to get to it, but its all fixed and I had it tested and it passed!

I found out that after I had removed the carb to replace the power valve, an vacuum hose had come loose. Turns out its the main one that draws manifold vacuum to the system. With the loose hose, that would cause the power valve to remain open and significantly enrichen the mixture through all RPM ranges.

Here is how dramatic the change is:

Before:
HC(ppm) 170 standard, 224 reading
CO(%) 2.11 standard, 6.10 reading
Nox(ppm) 2320 standard, 519 reading

After:
HC(ppm) 170 standard, 40 reading
CO(%) 2.11 standard, 0 reading
Nox(ppm) 2320 standard, 2318 reading

The only difference here is the vacuum hose was re-attahced!

What puzzles me is that after it was fixed, Nox is just at the limit, and increased significantly. I've heard that when you bring HC and CO down, Nox always goes up. Why is that? The tech says faulty EGR and catalyst make for high Nox ratings, but I'm confused as to why they would be low when the engine running on a rich misture and spewing un-burnt fuel.

[carrotman]

Air is about 78% nitrogen. Nitrogen and oxygen combine only at certain high temperatures. When an internal combustion engine runs rich, the combustion chamber runs cooler, hence lower NOx. When it runs lean, the chamber runs hotter and NOx increases. EGR lets a small amount of burned gases (no oxygen) in at low engine loads, to help cool the combustion chamber and lower NOx. If the EGR lets in too much, or at the wrong time, the engine doesn't run right.

[taco]

heres what all my car friends do and they also run racecars that burn nitromethane,
they put 2 gallons of racing alchohol in the tank and fill it the rest of the way with premium fuel,
one of the guys took an 89 short bed chevy truck ( with no cat at all) and it got the most wanted fast pass and they never thought twice of it,
on another note did the 77 cherokees even come with a cat because mine does not and im thinking it did because it has the air pump so it must have been a california jeep

[J10Mike]

taco,
i know my 82 j10 did not come with a cat. according to the tag under the hood, it's a "non-catalyst vehicle". however, i don't know whether cherokees got them or not.

[Panoscopic]

carrot: wow, thanks for that explanation! That makes total sense.

Now, thinking ahead to next year, seeing that I just passed the Nox by the skin of my teeth, what would you do to reduce Nox levels?

[carrotman]

Panoscopic, your HC is great, but the CO looks lean. I would pull a spark plug or two and check color against a chart. If they only check emissions at idle, you can adjust the idle mixture screw(s) to richen it.

This is where a vacuum gauge comes in handy. Will also tell you if there's a vacuum leak and other things. With the vacuum gauge hooked up to full manifold vacuum, turn each mixture screw out 1/4 turn while watching gauge. Should rise. If not, turn back 1/4 to original position. Should then check EGR, correct hose position, delay valves, etc.

[jackopak]

I had trouble with nj emissions, got carb redone at carb usa, half tank of 91 octane, and 1 can of denatured alchohol. the results where unbelievable... alchohol proves to make bad situations better, as always.