Rough Idle/Lean AFR
Thread Starter
Registered User
Joined: Jul 2024
Posts: 2
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Rough Idle/Lean AFR 1994 K1500 with a 5.3 swap. Recently started having some AFR/misfire issues. Went through the spark plugs, coil packs, checked for exhaust/vacuum leaks. At a loss here, any insight or ideas of whats going on would be appreciated. At idle not in gear, it idles high/rough. When shifted into gear the truck bogs down sometimes shutting off and then jumps back to normal idle. When driving around, anytime 30% or more throttle is applied AFR shoots up to around 25-30. Video is attached for reference. Thank you.
TECH Enthusiast
Joined: Sep 2019
Posts: 532
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I've had a similar issue with a carbureted engine, and I think it's misfire. The O2 sensor reads unburnt air, not fuel or lack of fuel. I would set the Terminator X to open loop at idle, not use the O2 sensor, and you can tune it like a carb where you find the settings where you get maximum vacuum at your desired idle RPM.
