AirSpeed VW Community Forums
Technical => Engine Tech Forum => Topic started by: 85fastlane on March 06, 2010, 04:12:44 PM
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Here's the deal, it's been a fun experience dealing with stupid emissions. The engine is timed perfect, advance is working, good spark, carbs are perfectly synced, idle at 700-750, ran it through 1/4 turn leaner than ideal running condition and here's my numbers:
Driving Test
Allowed Reading
HC 409 650
CO 4.76 0.30
NOx 4356 771
Idle Test
HC 1052 1264
CO 5.54 5.96
This is 4th time through, getting very frustrated, please help!!!
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It looks like you can increase your curb idle a bit , and advance your timing a degree or two to clean up your mid range HC levels. You may have to switch to smaller idle jets on your carbs, Try the first to steps and see how you make out,
Good Luck Jimmy D
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What is your engine? Carb? distributor? What is the timing set to?
Your super slow idle speed is hurting you. Spec is 850-950, and aircare allows up to 1100. If you set it to 1000-1050 your numbers should drop quite a bit.
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bruce gives excellent points , without knowing specs of your motor it is hard to recomend exactly what to do.
if your motor is mechanical sound - GOOD COMPRESSION AND LOW LEAKAGE it can be fixed if not forget it and repare the motor.
if you look at your readings your idle jet is to small , i would increase it to get my cruise CO #'s up then trim it at idle with the mixture screw or screws.
the car will drive better and get you your pass
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The engine is a fresh 1600 (my first build) T3 so only about 100 miles on it so far. Carbs are Weber 34ICTs, timing at 7.5 BTDC. I set idle according to Muir (600? Wow!) and it's so slow it rattles my junky old square at idle. Anyways, I set the screw back in a 1/4 turn to where it ran best before and then threw in some Methyl Hydrate and passed due to the need for having my car on the road. So I'm done with aircare, but do you feel these numbers are bad enough that I should be doing something about it for driving it daily? I think I'll bump up the idle for easier running when cold. I'm an extremely broke student, so I think I'll leave things alone since it runs smooth, unless there's free things I can do, haha.