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Hi everyone! I'm the ecstatic new owner of an 85 Alfa Romeo Spider Graduate. Car runs and drives great, was garage kept, and last owner did an okay job at keeping it driving strong (sort of a partial restoration). Unfortunately the vehicle will not pass Colorado (Denver Areas) tight emission and fails for high HC and CO out put. NOX is great. Have taken the car to three shops and mechanic will not touch the thing! I went on this thread and found some great info to get me started with the trouble shooting -running very rich- and so far have changed the spark plugs, which yes were full of soot and the number 4 wasn't gapped correctly. Surprisingly car ran better and had it re tested. Still failed for same reasons but now the HO is only failing slightly instead of double the limits :). Now I read that when the O2 sensor fails the cars from this time are designed to automatically run rich so as to not cause any catastrophic failures in the block. I have one on order and it looks like it has never been replaced and the car has 160,000 miles. While I'm waiting is there anything else I should check for? Ive looked into changing the air temp sensor but honestly I cant even find a diagram of where it sits let alone any working manual for the vehicle. Any help would be greatly appreciated. I can't wait to get back on the road and get some time in before the real winter rolls in.
 

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You're right about the system going full rich if the o2 sensor fails. 1 change at a time is probably best as you chase this problem. There are a few other things to check. The engine has a cold start valve on the passenger side valve cover. It's easy to test and you can find info in the FAQ at the top of the forum.

There is full info on the injection system in the FAQ as well. Time to get out the voltmeter and start checking. Keep notes on that you find!
 

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Welcome to the BB. How about some photos? We likes photos.

In addition to a failed O2 sensor causing the engine to run rich if the thermostat is faulty (stuck open or set for too low a temp) the computer will remain in its 'warm up' mode (slightly rich). Likewise, a faulty CTS (Coolant Temp Sensor) will make the computer think the engine has not warmed up. Note that the CTS is not the gauge sensor.
 

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Discussion Starter #5
WOW already tons of excellent advice! Really glad I found this BB. I will take some pics and post them soon along with what I find. Thanks again everyone!
 

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You have the actual numbers?
High HC and CO with low NOx can indicate, as mentioned above, that it wasn't hot enough. Could be thermostat etc issues, or could be it just didn't get hot enough. How is the temp gauge reading? NOx increases with heat, so low NOx is kind of an indication of temperature. Also, a low NOx number means the cat is probably good.
Have you done a compression test? That can tell you a lot. High HC can be an indication of low compression, poor combustion.
Andrew
 

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WOW already tons of excellent advice! Really glad I found this BB. I will take some pics and post them soon along with what I find. Thanks again everyone!

This place is the BOMB when it comes to you spider. Friendly, Helpful, Picture lovin car guys. Don't forget the pictures, this place runs on pictures. :)
 

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Make sure the thermostat is working and the car is getting up to temperature. Replace the O2 sensor. Check for false air leaks in the intake system, cracks in the inlet tube or the inlet runners. Get an infrared thermometer and do a before and after reading on the cat after it is well warmed up. There should be a temperature increase through the cat.

The inlet air temp is measured inside the AFM (air flow meter). Unless someone has pried the cover off and messed with the spring, they are very reliable. Is the idle smooth and even? If it is uneven (surges) look inside the AFM and move the vane and make sure it is not sticking.

I have the exact same car and when I got it in 1996 it had about the same mileage. My cat was shot, when they cut it out to put the new one in, there was nothing inside the old one. I'm in California and the new cat installed was less than $300. It's probably $50 less there.
 

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run a 3 wire sensor,, better system, easy to wire in. a ford taurus o2 sensor are cheap.( 45.00). 1 wire grey is to pre-heat it, the other grey wire is to ground( won't matter what way you hook op these wires) the last wire is to the ecu..
 

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Nevermind the air temp sensor.
Its built into the AFM and completely unchangable unless you intend to change out the whole AFM.

If you're looking through the AFM for some reason or another, the ATS is that little white plastic nubbin thing that protrudes from the upper part of the tunnel through the AFM
 

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JakeCake- I had a similar situation last summer with my 1986 Spider. My car failed for high HC emission at idle, 223 ppm. I increased the idle (it was just under 700 rpm) to just under 1000 and HC emission went to 157 ppm, which is a pass.

However, the CO emission was still too high. Consulted the Alfa Workshop manual (Check and Adjustment of Idle RPM and Exhaust Emissions, pp. 00-25), and adjusted the air flow sensor by unscrewing the adjusting screw out 2 full turns.

Drove back to the emissions shop (20 minutes of driving) and passed.

RPM= 847

HC=37

CO=0.02

CO2=9.9

O2= 6.99
 

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I think his Colorado test was on a dyno like in California. The idle CO adjustment would not affect the emission test results off idle.
 

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Discussion Starter #15 (Edited)
Thanks again everybody for your help. Duke58 I am not sure about the HC being read in colorado in PPM or how they read it but I am going to post a picture of the exact and most recent Test from the state with the numbers and the graphs if anyone knows how to better read it (god know I don't). Thanks again for all your help. Still waiting on the O2 sensor, should be here monday or tuesday. As for the AFM its not sticking and the response on the throttle is great. The idle is smooth as well but the exhaust still smells sweet and well still rich. ANyways I'll upload those documents here shortly. Checked air filter- new and great and spent forever following all the vacuum and air line and surprisingly also in great shape, no detectable leaks. The three wire system I am hesitant on because I didn't know if all O2 sensor read the same. Something i defiantly was looking into though was the O2 sensor with the lead that goes to the 30,000 mile check O2 sensor light thing? I want to repair it as close to original as I can- as long as the parts are available and they aren't too pricey. Thanks again!
 

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how old is the cat..5- 6 years.. they do go bad very slowly..and the o2 sensor,, i change mine every 3 years, cheap to do,, keeps it fresh.. and o2 senosrs, if you think about it, are in one he!! of enviorment.. cool on the outside and 1/8" inside,, hot exhaust gasses passing by..
 

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all o2 sensors work the same way.. the extra wires are to 'heat ' the sensors up quicker.. and the ohter is for a gound..i use a 4 wire sensor on my car.. 1 wire goe's to the ecu, 1 wire is for the sensor gound( exhaust systems can have bad gronds do to rust) 1 wire goe's to the heater, and the last wire( grey wire, except the green wire on my car , are just for gounds and 1 for the heater)
 

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My car was tested at idle and then revved to 3000 rpm.

If you can access (pay a minimal price for an exhaust analyzer at a shop) turn the AFS screw out by a couple turns. We can retest for $10. If that doesn't work, turn the screw back to where it was and replace the O2 sensor and catalytic converter. Not cheap for either, not as easy as turning the screw out and back in if it doesn't work.
 

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Discussion Starter #20
Thanks everyone for all the great help. I got the O2 sensor hooked up to a voltmeter while the car was running and it was dead- sometimes intermittent at best. I finally got the O2 sensor in and replaced and read it out again- this time working and passed with flying colors for Colorado's emissions and running great. Just glad I didn't have to replace the cat on it!!! The old O2 sensor was actually busted up and the ceramic was shattered. Thanks again for all the help. Now to tackle the cosmetics of the vehicle so this spring I can really enjoy it! I'll post more pics to come.
 
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