1978 Super Beetle running rich

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casamagana
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1978 Super Beetle running rich

Post by casamagana » Sat Mar 21, 2015 10:11 pm

Hello all, new guy here. I've spent a bunch of time lurking, reading, learning. Now I think it's time to contribute a bit. I intend to share my adventure in getting a fuel injected 1978 Super Beetle to pass a smog check in California.

The initial smog check station readings showed high hydrocarbons (HC) and carbon monoxide (CO). What was odd was the high oxygen (O2) count. What this tells me I've got fuel and O2 in the combustion chamber but it's not burning.

Prior to the smog check I followed Colin's AFM adjustment instructions. I felt I needed to get in there early on as the lid was held on with a tie wrap and orange sealant. Someone was in there.

With the smog check as a baseline, I added an LM-2. It showed idle and cruise of 12.5:1. Now, the first change. I then installed a MSD 6AL. That was a trick to get the fuel injection working again. The best part of installing a hotter ignition is the LM-2 is now showing idle and cruise fuel ratios of 14.5:1 without any additional tuning of the AFM.

That's all for now. The morning will bring some AFM adjustment leaner and see how it drives. Thanks ahead of time for any comment or assistance in tuning.

Nick
1966 Beetle
1978 Super

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Amskeptic
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Re: 1978 Super Beetle running rich

Post by Amskeptic » Mon Mar 23, 2015 7:40 am

casamagana wrote:Hello all, new guy here. I've spent a bunch of time lurking, reading, learning. Now I think it's time to contribute a bit. I intend to share my adventure in getting a fuel injected 1978 Super Beetle to pass a smog check in California.

The initial smog check station readings showed high hydrocarbons (HC) and carbon monoxide (CO). What was odd was the high oxygen (O2) count. What this tells me I've got fuel and O2 in the combustion chamber but it's not burning.

Prior to the smog check I followed Colin's AFM adjustment instructions. I felt I needed to get in there early on as the lid was held on with a tie wrap and orange sealant. Someone was in there.

With the smog check as a baseline, I added an LM-2. It showed idle and cruise of 12.5:1. Now, the first change. I then installed a MSD 6AL. That was a trick to get the fuel injection working again. The best part of installing a hotter ignition is the LM-2 is now showing idle and cruise fuel ratios of 14.5:1 without any additional tuning of the AFM.

That's all for now. The morning will bring some AFM adjustment leaner and see how it drives. Thanks ahead of time for any comment or assistance in tuning.

Nick
This appears to be a case of ignition misfire that increased HC and CO readings.
I have not happened across a generalized reduction in A/F ratio based solely on ignition to the extent you purport here.

Do you have a CHT gauge hooked up? You should know that the air-cooled world is always between some rock and some hard place somewhere. Here, lean mixtures can damage exhaust valves and heads . . .
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

casamagana
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Re: 1978 Super Beetle running rich

Post by casamagana » Mon Mar 23, 2015 9:03 pm

Thanks for looking at my post Colin. I appreciate your input. Here are the detail readings from the smog check on 03/06/2015.

ASM 50/15 HC CO CO2 NO O2 RPM A/F Ratio (Calculated)

Fail(Actual) 114 2.93 12.6 182 .7 1753 13.6:1
Max Limits 232 1.46 1,434

ASM 25/25 HC CO CO2 NO O2 RPM A/F Ratio (Calculated)
Fail(Actual) 124 3.17 12.5 223 .6 1786 13.4
Max Limits 200 1.26 1,294


On 03/14/2015, I installed the LM-2. With no changes to the engine I recorded the following:

15 mph, A/F ratio in 2nd gear, 12.6:1
25 mph, A/F ratio in 2nd gear, 13.0:1

My initial readings are different form the smog check. I'm taking readings pre-catalytic converter; smog check measures at the tailpipe post catalytic converter. Also, their analyzer vs. my handheld tool. It's good enough as I'm looking for trends.

The car has no misfire that I can detect without an oscilloscope. I did perform a power balance test before adjusting the AFM by shorting each individual spark plug cable and noting the rpm drop. All dropped the same. I did not like any O2 in the exhaust with the HC or raw fuel left over. Something is not mixing or lighting. That's what prompted my I needed something hotter in the ignition system.

My experience with a 1968 squareback and smog check many moons ago led me to a MSD as a partial solution. Also, California, in my opinion, has some pretty tight emission standards for these air-cooked engines. I wonder if today's standards are tighter than when these cars were new.
1966 Beetle
1978 Super

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Re: 1978 Super Beetle running rich

Post by Amskeptic » Thu Mar 26, 2015 9:55 am

casamagana wrote:California, in my opinion, has some pretty tight emission standards for these air-cooked engines. I wonder if today's standards are tighter than when these cars were new.
I have never had a California emissions fail with a stock Volkswagen with breaker point ignition. Most of the time I come in with a crazy margin of error because, well, California scares people.

I have always changed the oil and oil/air filters, adjusted the mixture to 25 rpm drop off optimal rpm, kept the gas tank below half, gotten the engine thoroughly warmed up and kept it at operating temp right to the test.

California used car emission standards are more relaxed from when they were new. You should know that C02 and O2 emissions are not relevant to passing.

Am I correct that your NOX emissions are crazy high? That suggests way too lean and hot. If your CO readings are under the fail, you have some room to richen it up which will cool the NOX and reduce the HC which seems likely caused by lean misfire.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

casamagana
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Re: 1978 Super Beetle running rich

Post by casamagana » Thu Mar 26, 2015 6:43 pm

Thanks again for your thoughts Colin. This L-Jetronic is very new to me. Your AFM tuning procedure has been very helpful. Air and oil filter are new. I also edited the chart. I hope it is a little easier to read.

The NOx numbers measured are actually very low. I attribute this to a functional EGR system and the rich condition.

Yes, you are right in that CA does not consider CO2 and O2 in passing a smog check. In my experience, the CO2 number curiously is similar to the a/f ratio. Also, any O2 left over means it had oxygen available to burn and didn't. Sometimes this happens in a lean condition, more O2 than fuel. In my example, I have O2 and HC left over. In my simple mind, the engine did not burn the fuel and oxygen.
1966 Beetle
1978 Super

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Amskeptic
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Re: 1978 Super Beetle running rich

Post by Amskeptic » Fri Mar 27, 2015 8:44 am

casamagana wrote: Also, any O2 left over means it had oxygen available to burn and didn't.
Sometimes this happens in a lean condition, more O2 than fuel.
In my example, I have O2 and HC left over.
In my simple mind, the engine did not burn the fuel and oxygen.
Get simpler still.

You are close to passing, and you have plenty of room here to lean out. Your column titling threw me.
Let's not title a column "fail" when "Actual" will do.
Let's title California's requirement as "Max".

You are under the limits with regards to NOX and HC, that gives you room to lean out the mixture. Because both your COs failed, you need to do the whole map, wiper adjustment is called for.

By the way, the test has an idle and a low cruise component? Don't let the tester shift into a higher gear that actually drops the rpms at the higher speed test. You had only a 33 rpm difference!
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Re: 1978 Super Beetle running rich

Post by casamagana » Sat Mar 28, 2015 12:19 pm

I took the car in today for a 2nd smog check. Passed this time but I'm still not satisfied. I'll put a chart of the readings up later this weekend. There is still more room to lean the engine down as the CO readings a still over 1.0%. I'd like to see the CO around 0.5% or less. I don't have much more room to lean down the wiper adjustment. The contacts are all most at the edge of the board now. I'm starting to wonder if I have the correct AFM in the car. Still I'm grateful it is a bit rich. I'm thinking it’s easier to take fuel away than chasing down vacuum leaks.

Smog check technician insisted on testing 15 mph in 2nd, 25 mph in 3rd. Very hard telling someone how to do their job. Guess I'll be looking for a different smog station for this car next time around.
1966 Beetle
1978 Super

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asiab3
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Re: 1978 Super Beetle running rich

Post by asiab3 » Sat Mar 28, 2015 3:03 pm

casamagana wrote: Smog check technician insisted on testing 15 mph in 2nd, 25 mph in 3rd.
Is this not correct? 25mph isn't too high on a bug, so I'm curious if the higher RPM (vacuum advance included?) will yield a better result.

RobbieJustDontHitTheRevLimiter
1969 bus, "Buddy."
145k miles with me.
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SlowLane
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Re: 1978 Super Beetle running rich

Post by SlowLane » Sat Mar 28, 2015 3:14 pm

casamagana wrote:Smog check technician insisted on testing 15 mph in 2nd, 25 mph in 3rd. Very hard telling someone how to do their job. Guess I'll be looking for a different smog station for this car next time around.
Consider yourself fortunate that you found a smog tech who actually knew how to use a clutch and stickshift.
'81 Canadian Westfalia (2.0L, manual), now Californiated

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Amskeptic
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Re: 1978 Super Beetle running rich

Post by Amskeptic » Sun Mar 29, 2015 6:43 am

casamagana wrote: A) Passed this time but I'm still not satisfied.

B) CO readings a still over 1.0%. I'd like to see the CO around 0.5% or less.

C) Smog check technician insisted on testing 15 mph in 2nd, 25 mph in 3rd. Very hard telling someone how to do their job.
A) Be Happy.

B) Don't turn this into a numbers game. You want to see the CO below the factory .7% for what reason exactly? A Prius is in your future if you have conscientious objections to 1%.
The factory was already seriously unhappy with what .7% was doing their engines
My rationalization when I lived in California was that my four cylinder VW was putting out less total pollution that the 6 and 8 cylinder Doge/Ford/Chevy vans with the same payload.

C) Ain' that the truth . . .
Colin
(congratulations)
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Re: 1978 Super Beetle running rich

Post by Amskeptic » Sun Mar 29, 2015 6:53 am

asiab3 wrote:
casamagana wrote: Smog check technician insisted on testing 15 mph in 2nd, 25 mph in 3rd.
Is this not correct? 25mph isn't too high on a bug, so I'm curious if the higher RPM (vacuum advance included?) will yield a better result.

RobbieJustDontHitTheRevLimiter
My calculations for a stock late model beetle with the 3.875 rear axle ratio:
2nd @ 15 mph 1,726 rpm, 3rd @ 25 mph 1,720 rpm.
That totally negates the test's objectives.
If the test technician kept it in 2nd, 25 would be 2,800 rpm, a perfect cruise rpm.
There is no general rule that the results would be better at 2,800 rpm. A misfire-induced HC would be worse, NOX would go up and CO would go down if it were lean, but either way, it would be more informative for the customer to know how the mixture is at higher rpm, and it would meet the dictates of CARB more closely. Someone needs to tell the technician while he is on his break.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

casamagana
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Re: 1978 Super Beetle running rich

Post by casamagana » Sun Mar 29, 2015 8:19 am

Amskeptic wrote:
B) Don't turn this into a numbers game. You want to see the CO below the factory .7% for what reason exactly? A Prius is in your future if you have conscientious objections to 1%.
The factory was already seriously unhappy with what .7% was doing their engines

Colin
(congratulations)
No Prius for me. Ok, learned something new. This is why I'm am enjoying this forum. I thought I was shooting for .1% CO on an injected car. I have the decimal one position off. 1.0% sounds reasonable to me.

And you're right about be happy. I finished the ownership transfer right after the smog check. :sunny: Also, I'm very impressed with cold start up and driveability compared to my '66 Bug. I'm liking this fuel injected engine.

Thank you to everyone who commented on this thread. I appreciate your time, experience, and expertise.
1966 Beetle
1978 Super

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