1980 Vanagon won't pass California smog

[LordHuron95]

Hello all, I've been chipping away at things to try and get it to pass smog. It did back in 21 but later that november, it ended up losing a valve seat.
Since then, I've had an engine rebuild. New heads, hardware, seals, hydraulic lifters, camshaft, ignition harness, ICU, rebuilt injectors, and probably a few others I'm not recalling right now.

I've tried adjusting timing several different ways. As the haynes says, the bently, my smog mechanic and a couple users on here. Theyve given mixed results but nothing passed obviously. Results ranged from 3.31% CO @15 mph and 3.83 @ 25 mph, down to 2.0 and 2.3. Passing are 1.46 and 1.26. So still a little ways to go.

Below are my readings from last week regarding the AFM, as some have pointed towards:


Here are my new readings from today vs the first ones from over a week ago.the new ones are off the van, I ran it for about 45 minutes yesterday but not at all today.

6&9 spec:200-400 read:430 2nd 330
6&8 spec:130-260 read:290 2nd 215
8&9 spec:70-140 read:190 2nd 119
6&7 spec:40-300 read:115 2nd 47
7&8 spec:100-500 read:245 2nd 168

6&27 max:2800 @ 68°F read:2920 @~65°F
2nd: 3210 @~60°F

Resistance strip test, touch terminals and slowly open air sensor. Resistance should not be lower than 40 or higher than 500.
7&8 test. 145 closed, 25 open. Spikes over 500 several times, as high as 1200
2nd: 168 closed, 23 open. Exceeds 500 several times.
6&7 test . 54 closed, 230 open. Spikes over 500, as high as 1600.
2nd: 47 closed, 221 open. Exceeds 500 several times

The first 5 tests all came back lower, maybe the temperature is a factor? But now they all passed. However the 6&27 got even higher, probably due to the temp. And the resistance strip tests are still out of spec.

Also, two days ago I replaced my TSII sensor. With both out of the vehicle, the old one tested ~3100 ohms while the new one tested ~2000 ohms. However took the van in today and no significant change. The shop just did a quick test, not a full test, and got 2.1 and 2.3, compared to the last 2.0 and 2.5.

I intend to look into the cold start injector for leaking, but wasnt sure where else to go afterwards or in addition to.

Fyi, I have run injector cleaner through it semi regularly and about a month ago ran emissions system cleaner.
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Never swing a mean loop. Never do dirt to man nor animal.

-1980 Vanagon Westy

[MarkWard]

There is a fuel mixture screw in the air flow sensor body. Have you tried leaning it out? The original mixture spec was measured pre cat. Are they sniffing at the tail pipe? Have you verified the fuel pressure? If it’s too high out of spec, it will run richer.

[LordHuron95]

[Abscate]

That’s running pig rich. You don’t have a little ways to go, you’ve got something dumping fuel or not enough air going in. These cars will pass by 1,6 country kilometers when things are right, not just squeak by

See this thread - even with a nasty HC score, this T3 was running 0.25-0.3% CO , 2-3x below fail threshold

https://www.thesamba.com/vw/forum/viewtopic.php?t=802789&highlight=smog+test+results
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[kamzcab86]

What was the outcome of this: https://www.thesamba.com/vw/forum/viewtopic.php?t=757078 ?
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1990 Vanagon Westfalia: Old Blue's Blog
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[LordHuron95]

[MarkWard]

You’d back it off or open the bypass. From memory it’s worth around 1% on CO. When these were new, we had the opposite problem. They ran too lean. We figured out ways to richen them, not what you are attempting.

Here are a few ideas I haven’t tested. Could you add a heavy duty resistor to slow the fuel pump down? Replace the pressure regulator with an Aeromotive adjustable one and lower the pressure? Introduce a metered vacuum leak?

These engines like fuel and will last longer if they aren’t leaned way out. I’d suggest an EGT gauge 6 inches from the exhaust valve. 1200 to 1300 F is safe. Or adding an AEM wide band oxygen sensor gauge. Then you can monitor mixture.

First task is to pass emissions, then you can optimize the mixture for the engine for longevity.

One last thought. Is this a dual diaphragm distributor? If so, that may have failed and you are not getting enough timing retard at idle. Easy to check.

[Xevin]

IIRC you said the camshaft, crank, deck height, Compression Ratio, P&Cs etc etc were all in original VW specifications for a 1980 CA spec type 4?
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[airschooled]

Can you post the full report? People that actually know what to do need all the information possible. High CO is usually rich, unless it’s not. Smell of gas can be a lean misfire. Excess O2 in the exhaust changes things. Any advice given based on one of the five exhaust gases is missing 80% of the necessary information.

I don’t tune engines on guesswork.
Robbie
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[LordHuron95]

[LordHuron95]

[airschooled]

I'm sorry, but I can't read those numbers formatted all over the place with no alignment or borders/cells/units/labels.

A shop running a machine in manual mode is great for tuning, but L-Jet doesn't hold mixture steady from the instant you read it. A real test (or pre-test) is 30-60 seconds of sampling at a steady speed. The results you see the instant the car hits 25 on the dyno are nothing like the results you read 45 seconds into the test. (Generally speaking, L-Jet runs cleaner the longer you hold speed and RPM with a steady foot.)

If you're failing all the gases by a little bit, it sounds like your catalytic converter is dead. Without an EGR, you'll need a lively three-way cat to get NOx down at clean CO levels. Reducing HC and CO generally bump up the NOx, so there isn't a lot you can do just by tuning.

Robbie
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One-on-one tech help for your vintage Volkswagen:
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Road trip reports and tech blog:
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[LordHuron95]

Things that I have replaced a couple months ago/less than a couple hundred miles ago:
spark plugs, wires, rotor, dist. cap, air filter, oil, oil filter, oil strainer.
_________________
Never swing a mean loop. Never do dirt to man nor animal.

-1980 Vanagon Westy

[airschooled]

Thanks for adding the color breakdowns. I personally think you’re wasting time running partial tests without getting steady readings of all the gases.

What kind of warm up are you giving the van before testing? At least twenty minutes drive, and no shut downs or extended idle sessions? An old cat that cools down doesn’t help you at all.

Robbie
_________________
One-on-one tech help for your vintage Volkswagen:
www.airschooled.com

Road trip reports and tech blog:
https://www.patreon.com/airschooled

[LordHuron95]

[Nitramrebrab72]

Link


In the earlier videos he shows how to adjust moving the spring. The spring weakens after time and a slight adjustment will bring it back to spec . AFMs are made to be adjusted and should be adjusted to best suit the engines condition to get the best out of it.

[Abscate]

Both your HC and CO are high. You could have both a failed converter and a rich condition. Test injectors for flow and dribble. If it’s an aftermarket magma flow more than a year old, it’s time to say goodbye
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[LordHuron95]

[LordHuron95]

Just now checked my cold start valve, no sign of dripping/leaking
_________________
Never swing a mean loop. Never do dirt to man nor animal.

-1980 Vanagon Westy

[Howesight]

I can't really decipher your data on the testing results. I will point out, however, that it is critical to have a good (new is best) oxygen sensor installed and also add that any aftermarket CAT is, realistically, ineffective after a couple years of normal running. With the disconnected oxygen sensor that appears in some of your posts, it's quite likely that the CAT is damaged from rich running.
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'86 Syncro Westy SVX