High Idle While Coasting - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Valkyrie14 · 10-24-2020, 05:34 PM

Background: I bought my SS with a BBK 95mm TB on it and had continual CEL issues. Just got a LS3 stock TB and swapped it out. Went for my first drive just now.

When I throw it into neutral coasting into a stop sign the engine holds at 2,000 rpms until I come to a complete stop. Didn’t do this before.

What is causing this?

InFiD3ViL · 10-25-2020, 02:09 AM

It may clear up with more driving. I am not sure of the idle or TPS relearn procedure on these cars. It may take several ignition and drive cycles.

Rich2010 · 10-25-2020, 05:13 AM

Mine does it too, but the minute I clutch in it’ll drop to idle.

RupertPupkin · 10-25-2020, 05:45 PM

Mine did that, but it ended up having a cracked spark plug.

RobZL1 · 10-25-2020, 07:39 PM

Throttle body relearn procedure may help?

Valkyrie14 · 10-25-2020, 09:09 PM

Quote:

Originally Posted by RobZL1

Throttle body relearn procedure may help?

I will try this in the morning.

Vegas Bound · 10-25-2020, 11:09 PM

I solved it with a 4L80e swap.

Batmanntexas · 10-26-2020, 08:32 AM

Check your tune for the TB area calculation. You dropped in TB size => airflow into the engine is now skewed slightly. Definitely tune related though.

NXTLEVL · 10-26-2020, 10:29 AM

Mine does the exact same thing. Nick Williams 102mm. I've got RDP doing a tune on it now to address this and other things. I'll update this thread once he's finished.

Greenhornet2 · 10-26-2020, 10:34 AM

Sometimes that is in the tune to keep the rpms from dropping too fast and falling past idle causing a stall issue. Mine is tuned this way, when I clutch in the rpms drop to about 1400rpm for a few seconds before falling to 800rpm

Valkyrie14 · 10-26-2020, 08:37 PM

So this will either support the tuning answer or mean something else. When I press in the clutch the rpms go down to normal.

Valkyrie14 · 10-26-2020, 09:30 PM

Can a GM TB be ported to 95mm?

I could put my BBK TB back in get my GM TB ported out and then it would be equal.

RobZL1 · 10-26-2020, 10:04 PM

Quote:

Originally Posted by Valkyrie14

So this will either support the tuning answer or mean something else. When I press in the clutch the rpms go down to normal.

Then it's in the tune. There are in-gear and neutral/park rows in the airflow tables and also the spark tables. I incorrectly assumed the tune had been modified for the TB change- my bad.

And for what it's worth, if you spend enough time to get it right, you don't need to have the idle hang to prevent a stall. You can tune the throttle blade and the spark to properly catch the idle at the targeted idle speed under all conditions. That 1400 thing is not a necessity, it can be improved to drop straight down to idle rpm.

Valkyrie14 · 10-26-2020, 10:43 PM

Quote:

Originally Posted by RobZL1

Then it's in the tune. There are in-gear and neutral/park rows in the airflow tables and also the spark tables. I incorrectly assumed the tune had been modified for the TB change- my bad.

And for what it's worth, if you spend enough time to get it right, you don't need to have the idle hang to prevent a stall. You can tune the throttle blade and the spark to properly catch the idle at the targeted idle speed under all conditions. That 1400 thing is not a necessity, it can be improved to drop straight down to idle rpm.

That makes sense. I won’t pretend to understand the technical points of the explanation. I use a tuner, but want to learn how to use my HP tuner. I get intimidated each time because of all of the terminology I am unfamiliar with. How difficult would it be to tune for the GM TB?

10-24-2020, 05:34 PM	#1
Valkyrie14 Valkyrie14 Drives: Chevrolet Camaro SS Join Date: Mar 2020 Location: Eau Claire, Wisconsin Posts: 962	High Idle While Coasting Background: I bought my SS with a BBK 95mm TB on it and had continual CEL issues. Just got a LS3 stock TB and swapped it out. Went for my first drive just now. When I throw it into neutral coasting into a stop sign the engine holds at 2,000 rpms until I come to a complete stop. Didn’t do this before. What is causing this? __________________ 2014 SS LS3/LSA Supercharger, 10% Super Damper, 2.55 upper, AGP Dual Pump, ID 1050 injectors, Pegasus solid rear cradle bushings, LT Headers, Roto-Fab CAI, Elite E2 catch can, E85 corn fed, 160 Thermostat, Monster Twin Disk, MGW Short Throw shifter, Tick Clutch Master Cylinder, HP Tuners, JL Audio system.

10-25-2020, 02:09 AM	#2
InFiD3ViL Drives: 2010 CGM 2SS/RS LS3 Swapped A6 Join Date: Sep 2016 Location: Spring Hill, FL Posts: 4,570	It may clear up with more driving. I am not sure of the idle or TPS relearn procedure on these cars. It may take several ignition and drive cycles. __________________ 2010 CGM Camaro 2SS LS3 Swapped A6 - GPI LS3 SS1 .647/.638, (224/237, 112 +4, 7º overlap) on CamMotion 8620 core, BTR Platinum .660" Dual Spring kit w/titanium retainers, CHE bronze trunnion upgrade, stock heads milled @ .015, Melling HV 10296 oil pump, TSP 1-7/8" long tube headers (W/Catless Off-road Pipes), Corsa Xtreme 3" Catback, GPI Ported/Rod Mod Intake, Stage 2 Ported Throttle Body, Vararam OTR CAI, Mike Norris Gen 2 catch can + GM 1LE clean side separator, 160º thermostat - Megan Racing adjustable coilovers (lowered 1.75"), MRR M017 10/11" wheels-Tuned by Ryan @ GPI

10-25-2020, 05:13 AM	#3
Rich2010 Drives: 2010 Cyber Gray LS3 SS/RS Join Date: Jul 2017 Location: Barre, Ma Posts: 107	Mine does it too, but the minute I clutch in it’ll drop to idle. __________________ 2010 Cyber Gray LS3-BTR stage 4-480/428 RXT and 3.91’s

10-25-2020, 05:45 PM	#4
RupertPupkin Drives: 2014 Camaro SS 1Le Join Date: Feb 2016 Location: IL Posts: 1,583	Mine did that, but it ended up having a cracked spark plug. __________________ 2014 SS 1LE Money Pit/ Forged 402 CAM 22X/24X, .619/.617, 113 LSA/ LS9 Heads FIC 1200cc/DSX Aux Pump//McLeod RXT Clutch 730whp: 630Trq

10-25-2020, 07:39 PM	#5
RobZL1 fo'shizZL1 Drives: 2017 ZL1 Join Date: Aug 2017 Location: ATL Posts: 1,281	Throttle body relearn procedure may help? __________________ 2017 ZL1 M6 Black \| Maggie 2650 // 103TB // Big Gulp Past Rides- 2014 ZL1 M6 Red Hot \| Tons of mods 2004 CTS-V M6 Silver \| Many mods 1995 Corvette M6 Torch Red \| A few more mods 1992 Camaro M5 White \| A few mods

10-25-2020, 11:09 PM	#7
Vegas Bound Account Suspended Drives: 2013 Sparkly Red One Join Date: Dec 2018 Location: Hospitality State Posts: 2,558	I solved it with a 4L80e swap.

10-26-2020, 08:32 AM	#8
Batmanntexas Drives: 2012 Camaro SS (2SS) Join Date: Aug 2012 Location: Stafford, VA Posts: 1,372 View My Garage	Check your tune for the TB area calculation. You dropped in TB size => airflow into the engine is now skewed slightly. Definitely tune related though. __________________ 745RWHP/634RWTQ on 93 @ 10psi 806/676 on E85 @ 10psi COTW 9/8/14

10-26-2020, 10:29 AM	#9
NXTLEVL Drives: 2010 Camaro SS/RS Twin Turbo LSX454 Join Date: Aug 2018 Location: Detroit, MI Posts: 143 View My Garage	Mine does the exact same thing. Nick Williams 102mm. I've got RDP doing a tune on it now to address this and other things. I'll update this thread once he's finished.

10-26-2020, 10:34 AM	#10
Greenhornet2 Drives: 2011 Camaro 2SS LS3 Whipple Join Date: May 2019 Location: Connecticut Posts: 1,925	Sometimes that is in the tune to keep the rpms from dropping too fast and falling past idle causing a stall issue. Mine is tuned this way, when I clutch in the rpms drop to about 1400rpm for a few seconds before falling to 800rpm __________________ Whipple 2.9 CAI ID1050x injectors ZL1 Pump JRE FPCM JMS Voltage booster JRE Rough Idle blower cam BTR .660 springs CHE trunnion kit 1 7/8 Speed Engineering Borla Atak JRE scoop 1.5" lowering springs BMR trailing arms and toe links Cradle inserts 704WHP 603WTQ 93 octane

10-26-2020, 08:37 PM	#11
Valkyrie14 Valkyrie14 Drives: Chevrolet Camaro SS Join Date: Mar 2020 Location: Eau Claire, Wisconsin Posts: 962	So this will either support the tuning answer or mean something else. When I press in the clutch the rpms go down to normal. __________________ 2014 SS LS3/LSA Supercharger, 10% Super Damper, 2.55 upper, AGP Dual Pump, ID 1050 injectors, Pegasus solid rear cradle bushings, LT Headers, Roto-Fab CAI, Elite E2 catch can, E85 corn fed, 160 Thermostat, Monster Twin Disk, MGW Short Throw shifter, Tick Clutch Master Cylinder, HP Tuners, JL Audio system.

10-26-2020, 09:30 PM	#12
Valkyrie14 Valkyrie14 Drives: Chevrolet Camaro SS Join Date: Mar 2020 Location: Eau Claire, Wisconsin Posts: 962	Can a GM TB be ported to 95mm? I could put my BBK TB back in get my GM TB ported out and then it would be equal. __________________ 2014 SS LS3/LSA Supercharger, 10% Super Damper, 2.55 upper, AGP Dual Pump, ID 1050 injectors, Pegasus solid rear cradle bushings, LT Headers, Roto-Fab CAI, Elite E2 catch can, E85 corn fed, 160 Thermostat, Monster Twin Disk, MGW Short Throw shifter, Tick Clutch Master Cylinder, HP Tuners, JL Audio system.