240Z, 260Z, 280Z Performance / Technical Discussions related to performance motor enhancements, upgrades.

Idle Fluctuation

Old 02-16-2008, 05:44 PM
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Idle Fluctuation

So recently i took off all of the smog stuff on my 74 260Z. Its been sitting for over 10 years and recently ive finally had it running. when i first got it running it would run pretty well, i rebuilt the carbs and they seemed to be running smoothly, now i finished plugging up all of my holes in the balance tube, its hard to start and when it does start it needs to be choked up pretty good. if i let off of the the choke even when its warm the idle will fluctuate and go up pretty high and then drop down really low so its barley running or it will die, if it stays running it will just go up and down. I dont know how high its reving or how low its going down to since my tach isnt working, any help would be appreciated
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Old 02-16-2008, 05:49 PM
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Maybe you should put the smog stuff back on.

Did you check your timing? Sync your carbs? Check for cracked / loose hoses? Hoses in the wrong place?

Just because you removed the smog, doesn't mean it will still run correctly.
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Old 02-16-2008, 06:07 PM
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well i removed all of the smog stuff before i got it running and it was running fine, i had just temporally plugged the holes, and now that i have the hold plugged it doesnt want to run right
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Old 02-16-2008, 06:36 PM
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you probably introduced vacume leaks in your care free removal. you remove one thing at a time and start it up make sure it hasnt started to run differently then remove another thing and repeat.
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Old 02-17-2008, 04:24 AM
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i read this assuming that you already did the whole fuel system clean up to get all of the bad fuel and sediment out of there. but at any rate, it's easy to miss a few specs in a carb rebuild, so after you check for vacum leaks and do what everyone else has said, i'd go through the carbs one more time making sure that you havn't accumulated any sediment and that all passages are clear
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