Failing Emissions.... So close.. 85 GL

[BigAl]

So over the last couple months have been playing with my new hatch to try and get her through emissions. I am getting close but something is eluding me. The car is an 85 GL hatch 5 speed 4WD (EA81).

 

Done so far:

 

* General Tune Up (plugs, wires, corrected timing, oil change, air filter)

* Ensured proper float level on carb and adjusted idle speed

* Replaced catalytic converter

 

She is so damn close to passing, and the only thing I am over on is CO. The reading is 29.0 out of 20.0 allowed. This makes sense as high CO output is an indication of unburned fuel, which would also explain the intermittent after fires i get in between shifts

 

Strangely though, the service manual states that after fires are mainly caused by vacuum leaks and NOT by incorrect air / fuel mixtures. So I spent about an hour and a half hunting down vacuum lines and reconnecting a few orphans that had come loose or fallen off. My question is, could those 2 small disconnected vacuum lines have been my problem or do I need to be looking at adjusting my air / fuel setting on the carb?

 

Thanks in advance

Edited June 27, 2010 by BigAl

[monstaru]

i would clean your pcv, and take your EGR valve off and clean it as well.some sea foam through a vacuum line , or the top of the carb will do wonders for you as well.

 

replace all vacuum lines.it is really cheap to do.cheers, brian

[GeneralDisorder]

Backfireing is a combination of both rich mixture/misfire AND exhaust leaks. Without the fresh air from the leaks you don't have a combustible mixture.

 

Where in the RPM range are you having a problem with HC? There are multiple circuits in the carb and they are tuned in different ways depending on where you want the changes to occur in the RPM range.

 

Vacuum leaks will (generally) cause a lean condition, not a rich one. Typically a leak means more air and that generally means less fuel as the signal to the venturi's decreases because of the leak.

 

Your HC number is very close to passing, and if it's just at idle then you can easily adjust the idle mixture screw at the base of the carb and get it to pass. If it's higher in the RPM range then you may have trouble as that would indicate the carb is no longer jetted properly for the engine (worn engine internals) and without rejetting the carb about the only solution to that would be to add a second cat into the mid-pipe.

 

The other option if you just want to pass and don't care about actually fixing it would be to run 50% denatured alcohol (paint section at Home Depot, etc). It will run like poo but it will not blow any HC's

 

GD

[BigAl]

After looking at the graph, it looks like the high CO readings are across the board as far as speed is concerned.

 

Also, any advice on changing the PCV valve? I have never seen something so hopelessly buried under hoses and hardlines. After 20 minutes all I have accomplished is a slice in my palm and removing the attached hose. I don't seem to have a tool to get at it.

 

Thanks again

Edited June 27, 2010 by BigAl

[BigAl]

Correction to my original information as well. It is the CO that is reading too high, not the HC. On a side note, it occurs to me there is still some 44K in this tank of gas. Would the 44K burning off excess carbon add anything to the CO readings ?

Edited June 27, 2010 by BigAl

[ShawnW]

Why don't you drive it up to Cheyenne and back? I have had a couple old Subarus that wouldn't pass and had been thru countless short trips and no long ones. This cleaned the engine, exhaust, etc out and made it run great. I also run Premium around here in most of my cars it seems to be worth it for the gas mileage if you have a good tight engine. 44K is pretty subtle and I doubt it would sway your readings at all.

[BigAl]

Why don't you drive it up to Cheyenne and back? I have had a couple old Subarus that wouldn't pass and had been thru countless short trips and no long ones. This cleaned the engine, exhaust, etc out and made it run great. I also run Premium around here in most of my cars it seems to be worth it for the gas mileage if you have a good tight engine. 44K is pretty subtle and I doubt it would sway your readings at all.

 

Well she saw a few highway runs before the temp tags expired, but no good long runs. Engine seems to be in good shape, despite the rich condition, so I will give it a switch to premium and see how it does.

 

Thanks