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neo · Posted: Tue Oct 31, 2006 7:16 pm Post subject: idle mixture adjustment on 16V

Hi!

I've measured the emissions of my engine and I got the following results:

CO=2.37%
O2=1%
CO2=9.5%
HC=330 ppm

The car is a non cat and witouth a lambda probe. Engine code is 307.46. The manual says that there should be 1.5% CO. So i'd like to lower it. I know that I can do that by turning that screw on the MAF. But I don't know witch way to turn to get leaner mixture since I don't have access to the gas analizer anymore.

Thanks!
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stedee · Alfa 33 Joined: 02 May 2006 Posts: 364 Location: brighouse

check your air filter that can be a cause of high co -i dont like to mess with the original settings because they are right and something else has changed.
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neo · Posted: Tue Oct 31, 2006 7:36 pm Post subject:

Air filter is new.
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bobbber · Posted: Tue Oct 31, 2006 9:18 pm Post subject:

Steve is right.

Perhaps getting some abnormal readings from sensors.

Bob
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neo · Posted: Wed Nov 01, 2006 12:35 pm Post subject:

I've checked everything. No errors on the ECU, all sensors reading normal. The thing is that this is not the original ecu instalation from my engine. It came from a donor engine. Including all sensors. So I don't even know if the setting on the MAF is factory.
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stedee · Alfa 33 Joined: 02 May 2006 Posts: 364 Location: brighouse

hmmmmmmmmm i dont know which way to turn it but there are posts on here about adjusting the flap to trick the ecu that more air is coming in than really is maybe you could do the opposite its to do with a `w `spring that controls how much force is needed to open the flap on the maf.i think if you search under tuning you may find it
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johnboy · Posted: Wed Nov 01, 2006 9:28 pm Post subject:

HI Neo

From memory,to make it leaner.you turn the screw anticlockwise. the oppersite if you had carbs on your car.as this on a carbed car would richen it up.

hope this helps. plus do the airflow mod,it works trust me Wink

regards john
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BigAl · P4 Joined: 06 May 2003 Posts: 2990 Location: U.K Surrey

hey neo
I have the correct way to set up the idle mix screw at home somewhere, ill try to fish it it out.
Its something like screw all the way in until engine starts to hunt, then back 1/2 or a full turn.
I have also done the 5 min AFM mod Laughing

make a mark where it is and move it anti clockwise up to 5 notches, iv done mine 5, some people have done it 3, try it see wotcha think.
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Bellamachinna · Posted: Tue Jan 30, 2007 1:39 am Post subject:

Hi all...

Just for curiosity...

How do you adjust the idle screw on the AFM????????????????????????

Do you get a real change in idle speed?????

I ask this, because, last Saturday, i took my 16v to a specialist, and he disconnected the idle actuator before adjusting the AFM, and then proceeded with the adjusting. After some seconds of ajusting he would blip the throtle (at around 3000rpm), and then restarted the adjustment...

I never used this method, and was used to adjust the idle screw only, without messing with any other ancialiaries. (with little sucess)

The idle was adjusted higher, and after connecting the idle actuator, it would calm down.
He repeted the process till the idle was "silk smooth"

Hope this helps
P.Camilo
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