California Smog - HELP

[jakub421]

Hey guys!
Just took my 78 320i in for CA smog yesterday (non-cat), and unfortunately failed.
Everything looked good except for CO %, max is 1.41, measured 1.61. First picture

Damn
Figured I just had it set a bit too rich, adjusted the mixture screw on the fuel distributor lean until it started stumbling and then just barely rich until it smoothed out. Took it in again today to get retested, and it actually did worse! CO %, max 1.41, measured 1.81. Second picture

Not really sure where to go from here. All factory smog equipment is in place.
Some recent service within the year includes valve seals, fuel injectors & seals, all intake/exhaust gaskets, new silicone vacuum hoses, Petronix ignition, plugs, wires, all fuel tank hoses, intake boot, hot & cold CP and system pressure within spec.
Timing retarded back to Z-ball at about 2300 - 2400 rpms.

Some things that may be negatively affecting my test: plug gap too big, running regular gas instead of premium, fuel in oil(?)...

Third picture is results from when I took the test back in 2019 after I first bought it.

Any advice? Looking forward to getting this thing back on the road again. Thanks!!

[ascot]

The bigger plug gap should help to lower your numbers since you get a bigger spark. Premium fuel mainly helps to reduce your NOX reading since it helps to lower combustion temperature since it burns slower than regular fuel. If you are getting fuel in your oil I would recommend an oil change right before your visit for the smog test since gasoline is a hydrocarbon fuel and it will increase your numbers. You can check for fuel in the oil simply by pulling the dipstick and looking at the oil and feeling it as well as smelling it for the odor of gasoline.

[OLD MAN]

The bigger plug gap should help to lower your numbers since you get a bigger spark. Premium fuel mainly helps to reduce your NOX reading since it helps to lower combustion temperature since it burns slower than regular fuel. If you are getting fuel in your oil I would recommend an oil change right before your visit for the smog test since gasoline is a hydrocarbon fuel and it will increase your numbers. You can check for fuel in the oil simply by pulling the dipstick and looking at the oil and feeling it as well as smelling it for the odor of gasoline.

All good tips.

Not sure what to do with precat cars but, Depending on how much the car has been driven in the last two years?

New plugs and distributor parts - dose yours have points or electronic ignition? New points?

How much did you drive the car before testing it? With my 80 and 81 cat'ed cars I always drive them 30 to 40 miles at 65 plus mph on fresh gas and go straight to my smog test.

All gas is not the same so before smoging mine, I use up the old gas and fill it with a brand name premium fuel. The older my cars get the harder it is to get them to pass California smog testing.

Oil changes can help as old oil contaminates the burn. In our older cars some oil will get into the burn.

I usually do a small to complete tuneup ie new plugs, check the spark plug wires and clean out the distributor cap and rotor or replace them.

Depending upon the miles of your engine compression may not be as good as when it was new, this will effect how well the fuel gets burned in the cylinder. So everything else needs to be as good as it can be.

[320iAman]

CO% being too high is usually too much fuel on the other side of the equation - Air/Fuel ratio too little air can cause high CO%, the only other item I can think of too weak of spark right now..


Randy

[gsumzzz]

Please get those emissions correct so the rest of the nation can breathe easy. These old cars should be scrapped!

[320iAman]

Gary

Whats your secret to passing smog in Pennsylvania ? Put your EGR system parts in carb cleaner ?

Randy

[lulu]

put 1/2 cup denatured alcohol to 4 gallons of gasoline , do it right before getting it smog checked

[gsumzzz]

Randy
chill. I was just kidding. No smog here. Ep got my thermal reactor. Other parts junked if bad Boxed if still good. Amazing difference in m10 when strip of that stuff. Egr is worst of it. My carbon emissions are non factor with the low miles I drive each year. No cats yet for 78. California wastes/expends more energy and emissions testing your e21s out there than the cars emit. Dumb.

[jakub421]

Good news, just passed today!
Turns out it was excessive gas in the crankcase, I suspected this but did not check between the first 2 attempts.

Long story short, I was running a 32/36 on this before smog was due.
Shortly before I converted it back to K-Jet, the carburetor did start leaking pretty bad into the intake, and I never ended up checking the oil for fuel

Turns out that fuel getting thrown around the crankcase and in the valvetrain getting sucking into the intake was enough to throw the mixture out of whack. Replaced the oil and leaned it out a bit more right before the test.

Thanks again for the help! Back out on the road again!

4-10.jpg

EDIT: Just to ad some more info, car has 73000 original miles on it, compression test between cylinders is 162 +/- 3

[320iAman]

No Smog in PA and several other States as well yet not here. Gas in the oil--that's a new one, filled up at the pump yesterday---30 mpg--mostly freeway driving..


Randy