Emissions Help

[mtb001]

Trying to get through emissions but have question,

I have 75 2.0, the emissions controls are removed, 74 heat exchanger/exhaust installed. Only failing on CO at idle, first test was 4.5%, checked, adjusted, and verified everything, reset idle mixture on ECU, today CO was 3.05%. 91 octane gas, at running temp. Need to bring CO to 2.20% to pass, Is it possible? I have read i can put 2000 ohm adjustable pot to lean out idle more than ECU allows,

Thoughts appreciated,

[Dave at Pelican Parts]

Spec CO for the pre-75 914s was 3%.

Using a pot in the head temp sensor line can make the mixture richer; it won't make it leaner.

You can try decreasing the fuel pressure somewhat. If you go too far, the fuel will not atomize (it will squirt instead of spray) and your CO will go up again. And it may be tough to get the engine to a steady idle when it is leaned that far out--but it might work.

--DD

[mtb001]

The lowest i can get on CO% is in the 2.8% range.

I have the 75 exhaust system, is it just the catalytic converter that is needed since all other reading are in-line?

Has anyone cut/installed flanges to bolt the cat in for testing? similar to 911? It looks like there is room in the 74 exhaust loop to fit the cat, just need extra flanges to bolt in cat and/or a bypass pipe.

[Scrappy]

Some have had success by putting 10% alcohol in the tank. In other words, only put sufficient fuel in the tank for testing 90% gasoline and 10% alcohol.