Trouble passing California Smog Check - 1979 Super Beetle

[fiacra]

Yet another thread about failing the California smog check...

A bit of background: 1979 California model Super Beetle that I bought in 2006 with the intent of fixing up as a week-end driver. It ran well, but failed smog, and it urgently needed brake work so I garaged it with the intent of getting to it in the near future. It sat for 16 years. I pulled it out a few months ago and started going through it. Briefly (lots of other stuff done, but not really pertinent to this topic)...the tank was pulled and cleaned, all soft fuel lines were replaced, new filter, pump worked fine (fuel pressure tested perfectly at CSV supply line), sent all injectors out for refurbishing, new air filter, full tune with all new components, distributor was professionally refurbished, brakes fully done, etc... The AFM is a refurbished unit (put on by the previous owner) and I did test it with an ohm meter. New double relay installed. I had it pretested and it failed miserably - running really rich with a CO of over 30 at 15mph. Took it to a friend's shop and put it on his exhaust gas analyzer and it runs fairly lean at idle. He doesn't have a way of checking it under load. Checked the adjustment screw on the AFM and found it was almost all the way in. Backed it out a bunch and tested again. CO dropped to 13. Needs to be below 1.46. I took it to a shop and they tried adjusting it but unbeknownst to me at the time they did not have an exhaust gas analyzer. The mechanic told me they simply lean it out until it runs poorly, then turn the adjustment screw in a bit until it settles out. Tested it again after they worked on it and now the CO was 13.19. I tried leaning out the fuel mixture and turned the screw out at least 4-6 turns and retested again today. CO is now 11.55 at 15mph. Results from both tests are below. I MIGHT be able to back the fuel adjustment screw out more, but I thought I had hit the sweet spot where it would still run nicely. Just to anticipate a few questions...the shop told me the EGR was working properly. I tested it as well and it does seem to work. The catalytic convertor looks almost new so I have not replaced it. All tuning is right on spec. I'm using the Bentley manual as my guide. Compression is OK... ranges from 116 to 125. I tested it cold, the day I pulled it out of storage and before I started any work on the car. It seems to run and drive fine. I warmed it up thoroughly before testing and I've probably put 150 miles on it since taking it out of storage. I'm at the point where I'm about to give up, but before trying to sell it out of state I thought I'd solicit any feedback from the hive to see what I might be missing.

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[VW_Jimbo]

Vacum leak! That’s my first guess. 95% of the time it is the air boot has disconnected from the throttle bottom and just lays on it.

I am guessing. Go look and let’s hear about what you found!
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Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[fiacra]

I forgot to add that all vacuum lines were replaced, as were all of the hoses for the charcoal canister. I did not replace the air boot. I just rechecked and it is firmly in place with new clamps. I previously took it off and carefully checked it for any cracks and could not find any. That does not mean there aren't any, just none I could find. It was replaced by the previous owner, but that was almost two decades ago... I'm thankful he kept really good records.

Can you explain how a vacuum leak would cause it to run rich? I thought that would make it run lean.

[busdaddy]

I don't see any mention of the temp sensor 2 (TS2) ohm readings in your work list.
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[fiacra]

[FlyAU98]

Perhaps ethanol gas does the same thing…but back when Florida did emissions testing, the story was that adding a bottle of rubbing alcohol to your gas tank before the test would help the results…
I’d take that with a grain of salt…. But since you have the ability to test yourself…
_________________
======================
1972 Super Beetle

[busdaddy]

[heimlich]

The original distributor with the dual vacuum canister needs to be in the vehicle for this to pass. Can you take a picture of your engine area and post it here?
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[fiacra]

[VW_Jimbo]

I think it would be wise to eliminate a big question mark. You stated the injectors were refurbished. Always a big? on quality and what was done.

How about running an injector balance test? Let’s see what the volumes on each injector is!

Additionally what is your battery voltage at the battery posts? 12.6vdc would be perfect! How about reading voltage between battery negative and the engine case bolt? Looking for .4 vdc or less.
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[fiacra]

[fiacra]

[fiacra]

My thanks to everyone for all the questions/input! Any thoughts about the AFM being at fault? It's a big expense to replace it and I don't want to carelessly throw parts at the problem. Maybe I should be way more aggressive with backing out the adjustment screw? I followed the Bentley manual procedures for testing it and it did test fine. Still, the car is consistently running rich and the latest round of adjustments didn't significantly change that. Could a bad coil be contributing? I did pull a plug wire, hook up a spark plug to it, and then crank the car over. Seemed like a good spark, but the coil is old and I'm not sure of the maker. Those are the thoughts I've been having, but I feel like my thought processes are a bit disordered right now! Hence the appeal to the hive mind....

[busdaddy]

Since it looks like it's doing it at speed as well as idle the AFM is a suspect, I don't think the bypass screw will change the numbers enough to make a difference though, those are some pretty big Hc's.

Spark can play a part, it usually shows more at idle though, is it blue?, or yellowish?
I asked about points since some Epoints modules mess with the waveform signalling the injector pulse.

Here's a trip down a rabbit hole on AFM fiddling, it's for a bus, but the beetle is very similar, it'll give you a place to start from at least: https://www.thesamba.com/vw/forum/viewtopic.php?t=442112&highlight=afm
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[jinx758]

Verify vacuum advance diaphragm is ok & holding.

I'm unsure if you should have a Shepard's Crook. It doesn't take much gas to mess up the diaphragm.

I know less than nothing about your set up. Sorry.


Best luck ... stay safe

jinx
_________________
" It's not valuable unless you learn something from an experience. " Henry Ford

It's not unlike the same difference

You can't push a rope


VALVES (cold)
POINTS
TIMING
CARB (fully warmed engine)

SCRAPE ALL GROUNDS

My Craigslist rescued 100 footer :
1971 Standard Bug
1776cc dual port
034 distributor
38mm EGAS Carburetor

[fiacra]

[fiacra]

[vwoldbug]

What do the spark plugs look like and is dwell and timing right on. Also did you test fuel pressure with vacuum line on and off.

[busdaddy]

FI doesn't need a Shepherds hook, that's for carb models where gas is present above the advance port, there's no gas in a FI throttle body.

A "miss at idle" huh?, a miss will dramatically skew snog numbers in the way yours is behaving, you have to deal with that.
Spark strength could be a factor, have you tried pulling one plug wire at a time from the distributor cap while it idles and listened for a drop in RPM?, maybe it has a dead cylinder (or partially)?, that'll make smog numbers like you show.

As for replacement AFM's, I have yet to see a "rebuilt" unit that actually worked well, most have just gotten a cleaning or coat of paint with very little internal work performed. You have much better odds buying a used one from the classifieds, even better if you can borrow one from a fellow late bug that's a known good runner just to make sure it's the issue.

Classified search using "air flow meter": https://www.thesamba.com/vw/classifieds/search.php...ton=Search
And another for "AFM": https://www.thesamba.com/vw/classifieds/search.php...ton=Search
77-79 bug are the best match for your car, 75-76 will work, but only if a late one is impossible to find.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

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[VW_Jimbo]

I would first go back through a valve adjustment and be sure nothing changed. A blip in the firing cycle is a lean misfire, more often than not. Really odd on an FI system. Really think you need to find a vacum leak on that cylinder, or do an injector balance test.

What is the measured fuel system pressure running at idle and no vacum at the regulator? How about volume?

Anybody touch the EGR system?
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!