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Discussion Starter · #1 ·
i took my 87 5.0 5spd to emissions and it failed idle, it was 1137 and the limit is 220HC, and cruise it was 160 and the limit was 160, CO(cruise) was 0.03 and the limit was 1.1 Co(idle) was 0.04 limit 1.2. i tried the guarantied to pass emissions by CRC, engine has new autolite 25's, new cap, rotor, decent plug wires, it bucks when cold but when warm it runs pretty good, smog pump still intact and all vacuum lines good, i have 2cats instead of 4(should still pass right?) i will try adding some denatured alcohol next time, oil just changed egr has a leak in the diafram, what else...
 

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What was the timing at?
 

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Discussion Starter · #3 ·
it was stock, right at 10degrees, how low can i go 7,8,9??? cuz i know advancing timing raises HC
 

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From what I've heard through some reliable sources, cats are by far the top reason cars fail emissions. A quality set of high performance cats are just as good as stock ones. I ran a Bassani x-pipe with cats along with 24lb injectors @ stock fuel pressure (read I was getting more fuel than I needed) on a stock long block with 160,000 miles and 15 degrees of timing and still passed the dyno quick test (you have to stay below a lowered threshold for the first 90 seconds of the test and you pass) in IL when they were still doing it.

I would say though, that because you have a car that bucks when cold along with the high HC, your car is getting too much fuel, not burning the fuel right, or your burning oil. It sounds like your ignition system is up to par, I'd make sure those plugs are gapped right though.

Next would be the fuel system and base engine.

Question 1, do you have a stock fuel system, what's your fuel pressure at idle?

Obviously if you have an adjustable regulator or higher flow injectors, you may be getting too much fuel, you could also have a leaking stock injector or a messed up stock regulator

Question 2, do you use any oil, and do you see any blue smoke from the car?

Oil that's being burnt will show up as high HC as well, if it's bad enough, it can foul out plugs.

Question 3, I didn't see a cam in you're car despcription, does that mean it's stock?

A non-stock cam can cause you to fail emissions as well.

Beyond that, you can look at your MAF, O2 sensors, and Coolant Temp sensors as inputs that if they are messed up, will cause the car to run wrong.
 

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Discussion Starter · #5 ·
stock fuel system, no adjustable fuel pressure regulator, havnt check fuel pressure yet, just changed the oil and i dont burn any, stock cam
 

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I'd check fuel pressure at idle, it should be around 39psi.

Check the plugs and see what they look like, they're probably black and smell like gas from being run rich, make sure they are gapped correctly, if you accidently bumped the electrode installing them, it could change the gap.

The main fuel control sensors are the MAF, O2s, and CTS (coolant temp sensor). If any of those are messed up, it will affect how the computer interprets what's going on and affect your air/fuel ratio. If you get to that, you may want to see if someone will run codes for you to see if any are setting trouble codes before throwing parts at it.
 
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