LS1 won’t idle correctly
Thread Starter
Teching In
Joined: Apr 2026
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LS1 won’t idle correctly it drops and goes up in rpm range and almost dies when car is put in drive and is held on the footbrake, also is idling at lower rpm than usual when in park, could this be a tune issue or fueling issue with the car?
Thread Starter
Teching In
Joined: Apr 2026
Posts: 6
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yeah it’s got a stage 3 BTR, and it’s usual idle is set at 800-900 but about a week ago it started that idle, i don’t really have a tuner since i js moved to florida about a month ago but i remember last i got a retune he turned off my 02 sensors because i had this same issue back then but instead of just idling weird, it would idle weird and also end up dying, rn it wants to die sometimes but it always catches itself
Teching In
Joined: Jan 2014
Posts: 36
Likes: 13
Since BTR doesn’t post exact specs, all I can tell is overlap is greater than 10 degrees. You need a good tuner. My cam has 11 degrees and I struggle after 4 years of tweaking it myself. The “pro” tune I got wasn’t drivable. All I can say is, ignore the O2 at idle, the overlap lies - even to wide bands. The overlap pulls in fresh air, which isn’t part of the combustion event you’re trying to control. Unless you can find a very reputable tuner that can spend time on drivability, I would recommend buying HP tuners and learning. Leaning out the idle cells will help that oscillation. I fought that with mine.
Teching In
Joined: Jan 2014
Posts: 36
Likes: 13
+12.5 overlap is what Summit’s cam calculator spits out. Like I said, over 10 degrees. The rule of thumb posted somewhere on here is drivability suffers after +6 degrees. That said, you should be able to solve that. I solved it by leaning things out. Some cams have to run open loop at idle, I’ve played with both open and closed loop with mine. Getting fuel and base idle airflow right are important to keeping to idle steady. Fuel is the most important by far.
Launching!
Joined: Jan 2011
Posts: 202
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From: chicago
This is absolutely a tuning issue. Tune and fueling go hand and hand with tuning and yes it has to do with adjusting those parameters.
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TECH Fanatic
Joined: Jan 2018
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If the car's behavior changed weeks after getting it tuned, I'd be looking for mechanical causes. Like a vacuum leak or a misfire.
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If this is a new issue, it's not the tune. Despite what the internet says, tunes don't go bad like a gallon of milk,
Without a datalog, everyone will just be guessing...and there will be guessing.
Without a datalog, everyone will just be guessing...and there will be guessing.
Thread Starter
Teching In
Joined: Apr 2026
Posts: 6
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went and did a overhaul on the car js to fix any possible chance of it being a bad part and did plugs,02sensors,fuel filter and oil change cs why not and bam it’s fixed so thank you all for the suggestions