High hydrocarbons at idle

[purplepeopleeater]

Just a quick question hopefullly.
I took time 87 ranger 2.9 to emissions yesterday, did great on everything but the hydrocarbons at idle. 220 ppm to pass, I went through at 1427.

Have brand new plugs all gapped correctly, brand new coil
Brand new distributor,cap,and rotor. Set at 10 BTDC
Brand new IAC
Brand new MAP
And brand new PCV valve and grommet

I will replace plug wires and confirm no vacuum leaks. My question is, if I were to retard the timing to 8 deg BTDC, will that help to lower the HC at idle? Then once I pass I will re muteness to 10 BTDC

Thank you for any help.



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[purplepeopleeater]

An update to hopefully help someone else in need.
Along with all my previous replacements, I also through on a brand new set of spark plug wires and pulled the spout and retarded the distributor to 8 BTDC. And replaced the spout. This made the truck pass with out any issue at all. The HC went from 1427 ppm all the way down to 79 ppm. The truck does lack power and idles a bit more rough (barely noticeable). So i will be returning timing to 10 BTDC.

Hope his helps someone else


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[alwaysFlOoReD]

Glad you passed. Thanks for the update.

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[gw33gp]

Good to see you passed but I don't understand how retarding the timing can lower HC. It seems like advancing the timing would lower HC because it would give the HC more time to burn. I can understand how retarding could lower NOx. Maybe combustion in the internal combustion engine is more complex than my thought process.
I am still thinking the spark plug wires were the major contributor to lowering the HC at idle.

 

[purplepeopleeater]

I think you right on the plug wires, but after searching for hours, retarding timing came up on a few different forums with other cars, so I figured I'd give it a shot. Seemed to work, but not sure how much it actually helped.


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