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Runs rough when hot
Today I replaced the oxygen sensor on my 80 SC Targa. It started much faster (right off) and settled into a steady idle much faster than it had been. However, the longer I drove it and the warmer it got, the rougher it ran - especially at low speeds. Any ideas? I know it could be vacuum leaks, but wouldn't that show up immediately not just when hot? It hasn't been many miles since the PO replaced the spark plugs but it has been a number of years. Could that be an issue? Could it be a CDI issue? Any other suggestions?
Thanks! |
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04-21-2018, 02:16 PM
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Designer King
Join Date: Mar 2004
Location: Toronto, ON Canada
Posts: 5,499
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Check your mixture. If the O2 sensor was faulty the PO may have richened the mix to compensate.
As you mention vac leaks are always a possibility, as are fuel and control pressures. You need a fuel pressure meter for CIS to check this.
__________________
Paul Yellow 77 Sunroof Coupe/cork interior; 3.2L SS '80 engine/10.3:1/No O2; Carrera Tensioners; 11 Blade Fan; Turbo tie rods; Bilstein B6; 28 tube Cooler; SSI, Dansk; MSD/Blaster; 16x7" Fuchs/205/50 Firestone Firehawk Indy 500s; PCA/UCR, MID9 Never leave well enough alone |
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04-22-2018, 07:42 AM
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Titanium User
Join Date: Aug 2014
Location: NY
Posts: 3,251
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What year?
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04-22-2018, 08:41 AM
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Still here
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Interesting how the O2 sensor affected your startup idle. It should not be in play at a cold startup.
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04-22-2018, 09:02 AM
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@dg567 - 1980
@pmax - yeah, not expected. Lately, I needed to crank it a bit to get it started. As soon as I changed the O2 sensor, man it just started right off. I also noticed it was not hunting at idle on startup like it had been. I'm thinking there aren't vacuum leaks, because shouldn't vacuum leaks affect how it runs all the time - hot, cold, start, etc.? I think this is likely getting beyond me and since the weather is now getting great here in PDX and I want to drive, I think I may take it to my mechanic. We'll see... |
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04-22-2018, 04:13 PM
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Still here
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Quote:
Does it idle well if you unplug the O2 ? |
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04-22-2018, 05:36 PM
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Black Label
