LS6 Swap - a bit cold blooded
Thread Starter
Burning Brakes
Joined: Apr 2017
Posts: 877
Likes: 80
From: Frederick MD
LS6 Swap - a bit cold blooded
Good Morning All,
Have been shaking down my LS6/4L60e swap lately and it is running nicely. One issue I have is that it is 'cold blooded', when you first start it up it seems to stall a bit and die when you put it in gear to back out of the garage unless you give it a bit of gas, it seems like it should not need that, once it is warmed up it is fine. I have not had it tuned and I am running a fairly mild cam (LS1 Stage 2 from Cammotion). It starts fine and idles up to around 900 when cold and will idle closer to 600 when warm. I have been watching everything via the torque app and I am not getting any codes and all of the sensors seem to read fine, including the coolant temperature. I have checked fairly thoroughly to make sure there are no vacuum leaks. Any idea what the issue could be?
Just for comparison, with the LS3 I finished last year, I can start that up cold and put it in reverse and it backs out without any hesitation, it seems when it detects some load and the rpm drops it adjusts accordingly to bring the RPM back up, maybe the 2013 LS3 works a bit differently than my 2002 LS6/LS1?
Thanks,
Scott
Have been shaking down my LS6/4L60e swap lately and it is running nicely. One issue I have is that it is 'cold blooded', when you first start it up it seems to stall a bit and die when you put it in gear to back out of the garage unless you give it a bit of gas, it seems like it should not need that, once it is warmed up it is fine. I have not had it tuned and I am running a fairly mild cam (LS1 Stage 2 from Cammotion). It starts fine and idles up to around 900 when cold and will idle closer to 600 when warm. I have been watching everything via the torque app and I am not getting any codes and all of the sensors seem to read fine, including the coolant temperature. I have checked fairly thoroughly to make sure there are no vacuum leaks. Any idea what the issue could be?
Just for comparison, with the LS3 I finished last year, I can start that up cold and put it in reverse and it backs out without any hesitation, it seems when it detects some load and the rpm drops it adjusts accordingly to bring the RPM back up, maybe the 2013 LS3 works a bit differently than my 2002 LS6/LS1?
Thanks,
Scott
Melting Slicks
Joined: Jul 2019
Posts: 2,297
Likes: 2,016
From: MA/NH Seacoast
Looking at the specs, it's a pretty mild cam, which is probably why you've been able to run it without tuning.
That said, it'll need to be tuned in order to get it running perfectly. It's breathing more than stock, especially at idle, so things like your fuel, spark and air tables will need to be tweaked, along with idle air, timing and fuel enrichment.
Unless you have an AFR gauge on the car, I'd be careful driving it hard until you get it tuned. You don't want it leaning out under hard throttle.
That said, it'll need to be tuned in order to get it running perfectly. It's breathing more than stock, especially at idle, so things like your fuel, spark and air tables will need to be tweaked, along with idle air, timing and fuel enrichment.
Unless you have an AFR gauge on the car, I'd be careful driving it hard until you get it tuned. You don't want it leaning out under hard throttle.
Melting Slicks
Joined: Sep 2010
Posts: 3,312
Likes: 697
As said above a tune is in order. When I had my 98 Wrangler LS6/4L60E tuned he did it while I was driving. He something about "air cracker" setting that can affect the idle depending on the mods to the engine. Sounds like you may need a bit more fuel until the engine gets up to temp. Kind of like keeping the choke on a bit longer.
Melting Slicks
Joined: Jul 2019
Posts: 2,297
Likes: 2,016
From: MA/NH Seacoast
As said above a tune is in order. When I had my 98 Wrangler LS6/4L60E tuned he did it while I was driving. He something about "air cracker" setting that can affect the idle depending on the mods to the engine. Sounds like you may need a bit more fuel until the engine gets up to temp. Kind of like keeping the choke on a bit longer.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,216
Likes: 9,354
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
isnt that idle a bit low? I would think a cold idle would be over a thousand and hot would be above 750. I agree with all the tune statements. My neighbor fought with his for a long time until he got it tuned. Then some more as his tuner didnt adjust the tune for the tranny delete. He was a drifter and couldnt get the thing to run consistently. He found out the tune for the tranny was holdng him to about 40% power until they figured it out.
Melting Slicks
Joined: Jul 2019
Posts: 2,297
Likes: 2,016
From: MA/NH Seacoast
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
I run my CTS-V with the 6L90E in full manual mode sometimes and when downshifting the car will rev momentarily before making the shift. Hence, the reason I asked about the rev matching. I had a 370Z 10 years ago that rev matched with a manual trans. Worked good.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Burning Brakes
Joined: Apr 2017
Posts: 877
Likes: 80
From: Frederick MD