LS1 won’t idle correctly
Thread Starter
Teching In
Joined: Apr 2026
Posts: 6
Likes: 0
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
Likes: 0
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: 203
Likes: 6
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.
Trending Topics
TECH Fanatic
Joined: Jan 2018
Posts: 1,061
Likes: 200
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.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Gifts Neither Your Dad Nor Grad Will Shove Into the 'Trinket Drawer'
Brett Foote
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
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
Likes: 0
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