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Re: Failing California Emissions-- Advice? Posted by Justin VanAbrahams [Email]  (#32) [Profile/Gallery]
(more from Justin VanAbrahams) on Thu, 29 Nov 2001 03:18:40
In Reply to: Failing California Emissions-- Advice?, Kevin M., Thu, 29 Nov 2001 02:41:31 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Hold on there! There are some things here you need to know, and it may warrant a call to the Bureau of Automotive Repair. I believe you can have your car repaired by anyone you like, and retested anywhere you want. Smog Check II did away with a ton of the hassles of Original Flavor Smog Check, including elimination of requirements for Gross Polluter repair. Trust me, I've had enough cars flunk SC2 for NOx at this point. The only thing to remember is that California offers a waiver for certain cars for a certain period of time if you've spend $x at one of those Certified Repair Stations. For an '88 car, that limit is high (and may not exist), and it's necessary to remember that you can only obtain this waiver ONCE. When it expires, or when you next need a check (whichever comes first) you MUST complete any repairs at ANY cost necessary to do so - they won't issue that waiver twice in a row.
Do searches on the BBS for failed emissions - there is a ton of advice here. My personal advice, which you're free to take or leave, is to not mess around and simply prepare to spend some money. It's not like you'll be throwing it away - everything hereafter is standard maintenance and will need to be done at some point anyway. Coordinating these items with the semi-annual smog check saves money and time. And headaches.
My checklist includes:
1. Replace the coil with a Bosch Red Coil. $35 from IPS
2. Replace the distributor cap & rotor.
3. Replace the spark plugs - I use Beru Silverstones, but NGK is good too
4. Replace plug wires if it hasn't been done recently
5. Test AMM for proper resistance, replace with rebuilt if necessary
6. Test O2 sensor as per Bentley manual, $35 from IPS if it fails
7. Go buy 30' of silicone vacuum hose and replace all of yours
8. Go to the dealer and buy the five rubber grommets in the intake tract - one at the valve cover breather, one at the AMM->Turbo pipe, and three in the intake manifold.
9. Check your timing, verify it's no greater than 16 degrees BTDC (you can put it back later) - 14 is good to keep NOx down.
10. Check your vent control vacuum cannister as per Bentley - you can block it off if it's ruptured since this isn't emissions-related, but will cause emissions problems
11. Check your ELCD (charcoal cannister) as per Bentley, and replace if necessary. I've seriously "disabled" my ELCD on more than one occassion and it's never been caught. Still, you want this part working since gas vapors do kill the environment.
12. If you do all of this and it still fails, then replace your cat. Use the opportunity to upgrade to a 2.5" exhaust!
NOx are caused primarily by heat. I can't remember the number, but Nitrogen and Oxygen from the air combine at a certain, very high temperature. 1200 degrees F comes to mind, but whatever. The goal here is to have very efficient combustion, where you are burning as much O2 as possible while still keeping cylinder temps down low enough so that this reaction doesn't occur. Make sure your cooling system is in good shape (if it hasn't been done, it may be worth flushing the system, getting a lower temp thermostat, and adding some Redline Water Wetter in for good measure) and that may help. It *may* be worth hard-wiring the engine fans to stay on all the time - a simple way to do this is unplug your A/C compressor and leave the A/C turned on - that will force the driver's side fan to stay on all the time without actually engaging the compressor. It's a simple, non-invasive method of getting some extra cooling.
Another thing that can cause high NOx is carbon deposits in your cylinders. Unburnt fuel that leaves carbon in there acts as an insulator and keeps heat in, leading to NOx production. You can go buy that "Guaranteed to Pass" stuff from Pep Boys or wherever, which contains chemicals designed to break down these deposits. I've personally had VERY good luck with "GM Top Engine Cleaner," which should be available from any GM dealer for $5-$10 per can. This stuff requires direct application to your intake system (as opposed to being added to the gas tank) but does a very good job. Three cans of this stuff reduced NOx from 2000+ppm to a passing 1100ppm on my '88 900T a year ago. You know it's working when smoke starts pouring out of everywhere. Read the directions CAREFULLY. You can also use ATF sucked in through a vacuum port - the detergents in ATF clean cylinders out very effectively. Be cautious when using this, however, since too much sucked in at once can cause ultra-high compression and serious engine damage, too much over all can have negative effects on your catalytic converter. I use about half a pint in a mason jar sucked in very slowly (over the course of 5 mins or so) through the vacuum port that normally goes to the vacuum cannister. Three or four applications does a good job cleaning and produces GOBS of pretty, white smoke.
All that said, you can use your Failed report to get an idea of what's going on - take a look at your HC and CO numbers - I'll bet they are damned near close to zero. That means you have no gasoline leftover after combustion, but plenty of O2 and N... you are running relatively lean, which raises combustions temps. You wanna richen the mixture up a little to get some more gas to simultaneously burn more O and lower cylinder temps. New AMM and O2 Sensor will help here, as will curing ANY and ALL vacuum leaks, and updated ignition components ensure it's all getting ignited properly - this is where my list from above comes from. :)
Finally, if it comes down to replacing your cat, do be sure you've done all these things first. If your electronic emissions control systems aren't working properly or are out of spec, you CAN ruin a new catalytic converter fairly quickly. It *really* sucks to spend $200 on a new cat only to have to do again in a year or two. Besides that, if the exhaust shop you take it to is on the ball, they'll remind you that you are only allowed (by Federal Law, if I'm not mistaken) to replace your cat once every 5 years or 50,000 miles... that's important to note.
Others may have advice or corrections, but this is what I go on... :) Good luck, and welcome to California. Wait til you see how much it costs to register your car. :)
-Justin
posted by 66.123.9...
, Thu, 29 Nov 2001 03:18:40 <-- Viewing This Message
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