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If the problem were due to an over-rich mixture then wouldn't you expect the CO number to be high as well? That is the main reason that I suspect valve timing.
 

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Discussion Starter #22
If the problem were due to an over-rich mixture then wouldn't you expect the CO number to be high as well? That is the main reason that I suspect valve timing.
Well, the good news is that my cam timing is right on - the bad news is that my cam timing is right on and that’s seemingly not the issue.
Now, on to the cold start diagnosis ...
 

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I'm still pretty new to Alfas and this incredible community, but you all have been a fantastic help already. I'm hoping you can help me problem solve another issue with my 84 Spider.

The car runs great, but I've always known it runs rich. I took it in for an emissions test (I don't need it - exempt in Utah), and I was really surprised at the results. All CO numbers were great (.74 idle, .72 loaded) and the loaded hydrocarbon (HC) number was good (104); but the idle HC was 1508 (220 standard)! So, I need some advice problem solving.

What I know or what I've already done:
-Engine compression is good - 125 across the board (dry).
-I had already suspected a vacuum leak so I replaced all the vacuum lines - however, I'm not sure about the injectors leaking (air).
-Plugs are new - I'm not sure about the age of the wires, but they look good.
-CAT temps are good on the in and out sides. Not sure about O2 sensor.
-I replaced all filters - air, oil, fuel - and fluids.
-No noticeable misfires.

The car really runs really well, but that HC at idle is far too high. Ideas?

Thanks a ton for your help.

Ty
There should be an idle mixture adjustment at the air flow meter.


Notice the round aluminum plug on the side of the airflow meter. That plug is removed and a screw underneath adjust the idle mixture- this was only for authorized servers
 

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I suspect your injectors are dirty and not properly atomizing the fuel. Put a can of Techron in the tank and see if that helps.
 

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Well, the good news is that my cam timing is right on - the bad news is that my cam timing is right on and that’s seemingly not the issue.
Now, on to the cold start diagnosis ...
cold start? Is that a new problem
(your original post was just asking about high HC)

if hard to start cold, but easy to start warm, I'd suspect the cold start injector not firing.
 

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I went through this with my ‘85. I believe you have 1 or 2 problems. First it sounds like the diaphragm in your fuel pressure regulator may be toast. It’s an easy check. You may find, as I did, fuel flowing from the air side of the regulator. It’s an easy fix.

secondly it sounds like the o ring in your idle circuit is gone. Over the years they start to take a set. you can get some very bad advice about finding a replacement. I’ve frequently read advice about getting some close from the hardware store. Rubbish, you won’t get an o ring to fit and they won’t be formulated to work in gasoline environment. Remove the old o ring from circuit, measure it and then get the correct item from the o ring store. Install it correctly and you can begin to regulate your idle.

I disagree with the advice about adjusting the idle at the air sensor. That adjustment is sealed for a reason and you should never have to play with it. I’m equally at odds with adjusting your cams or replacing the O2 sensor with a 3 wire system. You can easily check the sensor.

Follow Occam’s razor. Do the simple things first.
 

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Discussion Starter #27
cold start? Is that a new problem
(your original post was just asking about high HC)

if hard to start cold, but easy to start warm, I'd suspect the cold start injector not firing.
No cold start problem. In fact, it starts and runs great. Just working my way through Greg's L-jet tune up process. I am currently waiting on a few parts.
 
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