2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

How do you decrease Hydrocarbon output at load

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Old May 11, 2004 | 03:27 PM
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How do you decrease Hydrocarbon output at load

safc was set at -17% but i still failed my etest.

Suggestions?

Here are the results
here are results of first test:

39 km/h roll on dyno
HC ppm limit =73, My car = 191
CO% limit = 0.41, My car = 0.06
NO ppm limit = 836, My car = 39

2nd test. Apexi BOV adjusted so it doesn't flutter (losened preload, maybe i should increase preload?)
safc -10% @ 1000 rpm
safc -17% @ 2000 rpm, operator manged to get the car to buck on the dyno
everything else -10%

results are:
HC ppm limit =73, My car = 145
CO% limit = 0.41, My car = 0.01
NO ppm limit = 836, My car = 126

So NOX went up, HC ppm went down, but not enough. i need more.


Mind you i passed the idle test, my HC ppm was 75 at 750 rpm.

HELP!
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Old May 11, 2004 | 03:27 PM
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YOur still too rich.
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Old May 11, 2004 | 03:33 PM
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There is no way in hell it is too rich... the car bucked. i subtraced 17% of fuel.

The narrow band showed full lean.
The EGTs were super high.
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Old May 11, 2004 | 03:37 PM
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HC is unburned gas...

Hydrocarbon emissions result from fuel that doesn't burn completely in the engine. HCs react with NOx and sunlight to form ozone, a major component of smog. Ozone is beneficial in the upper atmosphere, where it protects the earth by filtering out ultraviolet radiation; at ground level, it's a noxious pollutant. Ozone irritates the lung tissue and causes coughing, choking, and stinging eyes. Some hydrocarbons emitted in exhaust, such as benzene, are known carcinogens, and others, such as 1,3-butadiene, are suspected carcinogens.
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Old May 11, 2004 | 03:42 PM
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yes i know what HC is... if i go anything more then -17 then the car won't even run.

the ACV maybe be dead
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Old May 11, 2004 | 04:14 PM
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there is a trick that makes the ACV pump air into the cats all the time, you know that one?
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Old May 11, 2004 | 04:46 PM
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i was just thinking that, I'm looking at the FSm now.
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Old May 11, 2004 | 04:48 PM
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My car is having trouble passing emissions, but I have new spark plugs, filters, cats, etc. What do I do?
J-rats Recipe for cheating emissions if its ABSOLUTELY necessary:

1. Turn variable resistor to full lean, or as lean as you can get and still run.
2. Trick ACV into pumping air to the cat all the time by removing the FORWARD UPPER vac hose, and capping it.
3. Run 87 octane
4. Run your tank down till your almost empty.
5. 2-3 bottles of alcohol in the tank. Drive VERY GINGERLY to the emissions station.
6. Once you pass go, DIRECTLY to a gas station and fill up with regular unleaded.
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Old May 11, 2004 | 05:01 PM
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I agree about checking the ACV.

Have you done the simple things to make sure you're getting good spark (plugs, wires, etc)? Also, make sure your timing isn't retarded and that you don't have the initial set thingy jumpered.
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Old May 11, 2004 | 06:26 PM
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Do you have to pass a visual? If not, rip off the ACV and just run a hose straight from the airpump to the cat via the lower split air pipe.

What fuel pump?
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Old May 11, 2004 | 06:52 PM
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From: Mississauga
no visual, stock s5tii pump.
car is pretty much stock.
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Old May 11, 2004 | 07:04 PM
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if you run too lean, it will lean misfire and raise your hc's also.
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Old May 12, 2004 | 04:01 PM
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One thing I don't get, if you're running lean your NOx emmisions should go exponentially up. Yours went up, but not exponentially. I know rotaries produce lower NOx emmisions but from the test data I would have thought you could go futher...

Originally posted by J-Rat
3. Run 87 octane
5. 2-3 bottles of alcohol in the tank. Drive VERY GINGERLY to the emissions station.
Isn't running 94+ octane going have a similar effect? For instance in the mid west they have high octane levels because of a higher level of ethanol.
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Old Aug 22, 2004 | 07:41 PM
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I read of wiring a GM electric air pump to run continuous to the main cat.
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