Smog 2020 time! (Update: it passed!!!)

[SGKent]

I found that tuning in the 15's left the engine flat. Around 14.5 at low cruise made it more responsive, and then in the low 13's at WOT, which in a non-O2 sensor bus is most of the time above 40 MPH. My final numbers were set by the smog test itself. Tune so there is a tiny bit of O2 left but almost zero. That leaves one getting all the combustion the fuel has to offer at light cruise.

The down side is that this is a bit hotter overall than running leaner, HOWEVER running leaner pushes the burn into the exhaust valves and port, which in a VW bus is the worst place to send extra heat. It may give you lots of heat in winter but it also is where VW heads fail most frequently. Unless one has an EGT to tune off of, it really isn't a good idea to play with lean mixtures. The reason the NOX was high in those tests is the lean mixture.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[metahacker]

that's why it needs to be accompanied by lots of vacuum advance.
it will run cooler than stoich, and get better mileage.
and any tuning zone where you are hitting 15/16 AFR should not be one where you are able to notice whether or not it has power, those should be anywhere from 11.8 to 13.6.
if it is all tuned to close to 14.7, well, then you are just making it run hotter than it needs to while making less power at WOT and using more gas at very light cruise.
these rules apply pretty much universally to all gas naturally aspirated applications...
and when tuning for "ideal" WOT and light throtte, you will still have some areas that are close to stoic (whether you like it or not with jetronic).... not saying that 14.5 - 14.8 would be the devil, just that one should be tuning for WOT and light cruise to be ideal, and you will end up with some stuff in between, and that's normal.


incidentally, Stoichiometric for 10% Ethanol gas is 14.13:1 and 15% is 13.8:1....
so tuning lore may also be a bit off... and your 14.5 target for E15 in California, might actually be spot on with what is common "best practice" ... I can't say for sure

and it's also interesting to think that the introduction of ethanol in gas is kind of like the government basically figuring out how to lean all of our air-fuel mixes out .. i do wonder what that does, overall, to NOx, though

[Wildthings]

[ivwshane]

You guys are talking way over my head!

I did check for vacuum leaks and I don't know if it classifies as a vacuum leak but one of the intake manifolds is blowing air out where it meets the case. I do have the spacer on it and I did have a silicone gasket on it as well. I'll remove the extra gasket but should I put something on the phenolic spacer besides the paper gasket that is attached to it?

It also looks like I'll need to remove the fuel rail to take it off. What's the best way to do this without getting gas all over the engine bay? Choke the line going to the fuel pump and then disconnect the line from the other side of the fuel pump and drain it there?
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77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab

[metahacker]

[SGKent]

[Wildthings]

[ivwshane]

So after having hell of a time even trying to find a place to take my bus to get a smog (most places said they couldn’t do my bus), I found Aggie smog in Davis. When I called and asked him if he’d do my bus he required an appointment and told me to be sure my timing and idle were correct, that was a good sign in my eyes.

I took it in today hoping to do a pre test but when I got there he said they don’t do pre tests and California hasn’t allowed them in about five years. Which is weird because other places I’ve taken it in the past did pre tests for me. At this point I was like I don’t give a f any more let the cards fall where they fall.

He got it on the dyno with no problems (meaning he knew how to shift and drive such a vehicle), good sign number 2. He did his thing and he kept going back and forth looking at the engine sticker which is in rough shape. I offered to show him a better sticker but he said no need.

A couple of minutes later and the results were in...I passed!!! So much stress was lifted off of my shoulders I simply couldn’t believe it! He said it was the best running bus he’s ever seen:D whether that means something or not I don’t care because I passed!!!

Anyway here are the results, let me know what you think and if I need to tune it slightly for normal driving:

15mph test/25mph test
RPM 2092/2047
%CO2 14.6/14.5
%O2 .1/1.1

HC max 204/169
Ave 45/37
Measured 75/59

CO%
Max 1.66/1.46
Ave .26/.22
Measured 1.34/.47

NO
Max 1534/1394
Ave 586/517
Measured 1371/1255
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77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab

[ivwshane]

Am I reading it correctly that with the high NO, that indicates I'm a little lean?

Should I adjust the AFM externally to enrich it or should I change the timing?
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77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab

[SGKent]

[ivwshane]

No, CA with the CAT sticker, same as yours but with a stock cam (I believe).
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77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab

[SGKent]

[ivwshane]

There is a very good chance the EGR is the issue. With no rebuild kits available and no new ones I "hacked" it the best I could to make it functional (it was also thoroughly cleaned). However when I tested it it was functional in that the plunger worked and it was sealed and I adjusted it per the Bentley manual.

The CAT has less than 10k miles on it and is a rimco brand that is carb certified/compliant.

As to the compression ratio in have no idea but I'd lean more to stock than anything as I had it rebuilt in 2013 to fix low compression on one of the cylinders (kombi haus).

As for my initial AFM settings I'm pretty sure I followed the Bentley manual and set the screw to five turns out from tight.

My previous smog tests were rich with this same engine, except now all my seals, hoses, and gaskets are new.
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77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab

[SGKent]

You need a O2 gauge to properly set the mixture. It isn't a number of turns thing.

As to the EGR, as long as it doesn't leak, when you open it does the engine slow way down and want to die? If so it is working correctly. The EGR dumps into a tube that is inside the plenum. That tube has a series of holes so the gases flow evenly into all cylinders. Over time those holes plug up and have to be cleaned out. If you did it when the engine was rebuilt it should still be Ok.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin