Emissions problems .... Options

[jsteele22]

A few of my new friends in law enforcement convinced me to get my '76 2.0L registered, which means an emissions test. The PO had problems (back in '98) and the car hasn't been clean since then; that's one reason I had been putting this off.

I've already replaced points, rotor, cap, wires, and plugs. Adjusted dwell (which I feel pretty sure about) and timing (which I'm less sure about). For the timing, I used the handy template from Pelican Parts website, and put a visible mark on the impeller. But its so hard to work through that viewport that I might be off by a little either way.

Also, I ran 3 tanks of gas w/ injector cleaner (and *did* see some improvement during that time). I found that my decel valve did not work, and removed it. I had problems w/ the AAR wire shorting to ground, blowing a fuse, so I removed it. All of my vacuum hoses are new. And although my idle is still high (1146), I haven't been able to track down any leaks... The screw in the TB is all the way shut, and the knob on the FI box is all the way (oh jeez, which way was it ? - I think it was CW).

I adjusted the valves before the RRC (about 1000) mi of driving. That (simultaneously w/ timing) made a major improvement, as two exhaust valves were too tight. Towards the end of the RRC I did a little spirited driving (awesome) and on the trip home pushed kinda hard up a pass. Since then the engine has a slight roughness, so maybe valves need re-adjusting.

Anyway, the car idles at 1146 RPM, and the numbers there are : HC 1156 PPM (limit 600) and CO % 3.73 (limit 3.50). Of course, like an idiot, I didn't get the car fully warmed up before (it takes like 15 minutes of serious driving).





Anyway, my main goal right now is to get the thing to pass, fast and cheap. Failing that, if I put $75 into diagnosing the problem (at a legit business) I can get a waiver.
I won't need to do this again, as my county is cancelling its emissions program in Dec. '06

My other goal is to know what's wrong. I just got the car, and I know its burning a little oil (rings and/or valve guides) so I'm deciding how to proceed : I'm toying w/ a mild Subaru swap if I can do it cheap enough...


Any hints appreciated....

[dmenche914]

Good to have freinds noting oil smoke and valve noise. You didn't acknowledge the valve noise, but I'd check the valve clearance again, if they have changed drastically since last adjustment, then someting ain't right in the the valve train. This can cause burning oil (worn valve guides) and screw up the vacuum "signal' that helps control the D-Jet system. So if your valves are going bad, get the waiver and save for a rebuild. Might be interesting to do compression test both before and after a valve adjust. Also if you wait until a bad valve fails totally, you may end up scrapping the head, pistons cylinder etc... I hate it when valves break, constantly changing valve clearance (ie getting tighter) means the valve is stretching, valve head is wearing, or the seat is receding. Lossening valves mean the seat might be dancing around or the cam is going flat. Maybe the rocker adjusters are getting worn out, check their profile

EGR leaks will generally cause lean running as they (older ones) run off a vacumm signal, and a leak in the egr diaphram will cause extra air to enter the intake. The EGR works by keeping the combustion cooler by adding spent exhaust gasses to the intake. The spent exhaust gasses will not burn, so they are in effect "inert" for combustion in the engine, this "inert" gas dilutes the regular fuel/air mixture causing a cooler burn. NOx only forms above certain temperature, below that temp (i thinks it is something like 1400F) no NOx can form (Nitrogen is non-reactive unless really hot, so it will not react with Oxygen untill it gets that hot, else it stays as harmless N2) Some parts of the engine exceed this critical temp, things like exhaust valves and such that get the hottest will allow N2 to form NOx when O2 is present. Irony of it is that smog control for HC works best on a hotter engine. A colder engine will produce more HC than a hotter one generaly, so upping the heat as other smog measures require actually increases NOx, the egr is there to reduce the NOx. A three way catalyst is a neater solution for NOx, it uses the chemical reaction in the cat to reduce NOx.

Anyway lets see some compression numbers on the engine.

Do not just replace the catylst. Nothing will kill a new cat faster than a car burning any oil, or running with wrong mixture. You'll just waste a new cat, might make you "pass' but it will not last long until the real problems are fixxed.

Cats also have a limited life, and die, but frankly your HC leaves are near double that for my non-cat 1970 914, so your problems run deeper than just a dead cat. a new cat will mask the problem possibly, but die quickly as long as you are burning oil and/or running rich