Idle issues
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Did you check for codes? A bad O2 sensor will think it's running lean, compensate by delivering more fuel which will increase idle speed.
A bad throttle position sensor will cause high idle too. Start it, let it idle high, then shut off and restart. If it then idles normal suspect the TPS.
You visually inspected for a vacuum leak, but did you test the vacuum with a vacuum gauge? If it's normal at the intake port but lower on a line you have a leak somewhere. It's an 33y old truck. If the vacuum lines are original they can crack and collapse at anytime.
Has the brake pedal pressure changed?
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199 Posts
One more thing: If the thermovsc
One more thing: If the thermal vac flap in the air intake nozzle is malfunctioning and completely closed, it will run rich like a stuck choke on a carburetor. Your exhaust outlet will have black soot from the over rich condition. Remove the snorkel tube and take a look.
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12 Posts
Alright cold start after work and idled fine for first mile. Then it started idling 15-2500. It seems like it’s choked so I’m gonna look into thermal flap thing first. And brakes have been fine and still are but at startup this morning the brake light flashes 5 times? Brake fluid is full, not sure what that means
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Never mind. Fixed!! Thanks for help. It was my vacuum canister under the air filter. It lost a bolt and turned 45 degrees smh straightened back up and idles perfect again 👍
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