Failed Emissions test with carb'd '85 - what to do?
 

Here is the deal. The car ('85 GT Convertible) was running terrible with the stock "made by Holley" 4 barrel. So, I scrapped it in favor of the new "Street Avenger" series from Holley. Now, the car totally failed the emissions test in CO and NH (or something like that). Was wondering if just tuning the carb better would help or if I just need to put the stock carb back on to run through the test? Any of you have experience with something like this? I don't really want the pain of having to change carbs every 2 years!

Do all those stupid vacuum hoses on stock carb make that much difference in the emissions!?

Obviously I am CARB illiterate, so any help you can offer is appreciated!

Thanks,
AutoX

Yes, all those hoses make a difference, but there are still ways around them, from an emission output standpoint. If you are only required to pass a sniffer test, and not a visual test, then there is hope. Otherwise, you will have to have everything reinstalled to stock specs.

When you were tested, you should have received a print-out with your results. Hopefully it was done with a 4-gas analyzer. The info I need for each of the following are both the legal limits, and the amounts you tested at, for:

HC
CO
O2
CO2

If you were tested at idle and at a set speed, include the numbers from both tests. Please be accurate in posting this info.

Take care,
-Chris

tuning for performance and tuning for emissions rarely go hand in hand. and it will be more time involved to try to tune just for emissions then set it back for performance. it would be better to just take the 20 min. to swap carbs to pass the test. 20 min. every 2 years is nothing to worry about.

The test was done with a 4-gas analyzer. The test I had to pass was the "enhanced test" where they run the car on a "dyno-type" of resistance drums and do about 6 traffic simulated accelerations from zero to about 30 mph. The two places I failed were:
THC - Standard Max = 2.00
- My car Max = 4.22
CO - Standard Max = 32.0
- My car Max = 55.5
FYI the other two results were:
NOx - Standard = 3.70
- My car max = 1.25
CO2 - Std. Max = N/A
- My car max = 731.8
Now for THC, the car spiked up right about the time the car hit 28-30 mph. Actually the same for CO. I don't know if it spiked up as soon as he let off the accelerator pedal or what. Man, I wish I had a scanner so I could send this to you! I do have a Fax machine!?

They did lift the hood on the car. I threw the stock (i.e. HUGE) dual-snorkel air cleaner assembly on the car, so if there is something that can be done underneath that, we are fine. They did NOT remove the aircleaner lid or anything...
Putting the stock carb on the car would take away all the fun. I want to make this thing pass with an "illegal" carb on it!? ;)

BTW - it is only a 570cfm Holley Street Avenger carb. It has vacuum secondaries and an electric choke (which takes forever to turn off it seems! It idles high until the car is fully warmed up, even though the choke is turned down almost the whole way!)

Well, hopefully I have given you enough clues to be able to help me out. Let me know if you want me to fax my test results to you!

Thanks a ton,
autoX

Okay, your info doesn't make alot of sense, but we'll see what we can do. First, a 4-gas analyzer should have an O2 reading. You didn't list one. The CO, CO2, and O2 readings should all be a percentage, while the HC reading should be a number, representing Parts Per Million (PPM).

Either way, you're running way too rich. What is your fuel pressure set to? You need to adjust your idle mixture, and lean it out a little bit, and you need to unplug your choke. When you have made the necessary adjustments, and are ready to retest, you have to get the engine as hot as possible. Drive around town in second gear for 30 minutes before the test.

How are your cats? If you still have them installed, they are probably clogged by now. Do you have the air pump hooked up?

Good advice PKRWUD

Yeah, you want to get your exhaust (cats and mufflers) as hot as possible to more efficiently burn up as much polluntants like HC (hydrocarbons) as possible. If you take it in there cold, there will be a big difference in the test results. .....But you also need to be careful not to burn up your transmission driving around in 2nd at too high an rpm for extended periods of time. I don't think I'd suggest riding around in 2nd on the street at all for over a minute. Just find a better way to get the car heated up like take the LONG way there, accelerate hard a couple of times, and if possible, leave the car running as long as possible until they test yours. Don't make it just sit (turned off). PKRWUD this is said respectfully, no malintent towards you. ;)

Put in a good gasoline, like Chevron (with Techron), Amoco 93 (a slightly more refined gasoline), a few days b4 the test instead of Smile or some crappy gas. That will cut down (a LITTLE) on some emissions (I actually did some actual research on different gasolines and found Chevron--w/ techron-- to cut down on NOx a little, don't know about carbon monoxide and HC). Also, I read (I don't know if this is still the case) that Chevy, Ford, and Chrysler use Chevron gasoline to pass one of the EPA's most stringent tests-- not any other gasoline.

A tune up b4 going there would be great.

I actually do run Chevron Gas in all my cars. I will try to unplug the choke and lean it out some. Also, I had that "fuel stabilizer" stuff in the gas tank as the car was parked for the winter. I wonder if that would cause unfavorable results? Also, I swear I have seen some kind of "magic" snake-oil that you put in your gas tank that is guaranteed to make you pass an emissions test - have you ever seen or heard anything about that junk? I am not a fan of these magic treatments, but I wonder if it's worth a try?! Anyway, thanks for the help. In the meantime, I will probably work on rebuilding the stock carb - just in case. I have a rebuild kit and everthing for it anyways...

85 Mustang GT Carb
 

I have a 1985 Must GT. I had my car smogged last summer. Then I took detailed pictures of the engine compartment before putting on a new Holley 80457 600 cfm electric choke. All vacuum lines match to the new carb except the vent lines.

No sweat. I was being somewhat facetious while trying to make a point.

autoX-
The snake-oil you are referring to is prety much juat alcohol. Alcohol burns clean, and adding some to a tank already low on gas will improve your emissions. It will also tear up anything rubber or plastic in your fuel system. Your new Holley will quit running because the needle and seat will swell shut. I wouldn't recommend it.

Lower your fuel pressure, lean out your mixture, and get it hot. That should help you pass. Also, you didn't say whether or not you have cats. If you do, the rich mixture you have been running will clog them up, and render them useless. When you do the things mentioned, test it again. If it fails, post the numbers again, and by comparing them to the old ones, we'll be able to tell you what's going on.

Take care,
-Chris

I made it through the same test with the 80457s, AFR heads and 1.7's.... I'd say go get the cats checked 1st.. they make a big difference... also... if you used the wire on the stock carb for the choke, you'll have probs.. the stock carb uses 6v, the holleys need 12 to work... I just adjusted mine so the choke would kick off sooner...
might check the float level too... to high will cause it to run rich too...

I bet the cats are the prob though... easy for an exhaust shop to test... the pipe comming out of the cats will be hotter than the pipe going in...

oh yeah... you might check the linkage on the choke too... mine was hitting the stock heat shield... had to trim it some ;-)