The LS Swap Begins
- Thread starter beaufrusetta
- Start date
Depending on the tune too. I’m sure there is a fine line where you can get food reliable power and fuel economy in there too.
IIRC, the cast iron LS weighs about the same as the 4.0L, combine that fact with the added power, and the power to weight ratio of the LS swap in a TJ, and it HAS to get better fuel economy than a 4.0L.
Not the same but the 5.2 Dodge magnum in my TJ got roughly the same mileage as the 4.0.
Basically I'd ask others how much fuel they were putting into their rigs after running the same trail as me. And they would use roughly 1-2 gallons of what I was using.
Basically I'd ask others how much fuel they were putting into their rigs after running the same trail as me. And they would use roughly 1-2 gallons of what I was using.
OP
Yep! And I'm still getting the tune right, but I'm getting like 3mpg more than the 4.0L and having way more fun.
OP
Sooooooo...this is probably one thing I don't talk about because I usually will get flamed (and have flamed others in the past)...but I ordered them off of eBay. Yep...$86 shipped to my door...and they have been absolutely fantastic. My thoughts were...I don't live in a place that will see rough winters and advanced corrosion...and if they arrive with holes in the welds, I can just walk across the street to my buddies house and we can fix it right up.
I figured even if they ended up being total crap, I'd only be out $86...that's less than taking my family out to dinner...so, I wasn't concerned, and I've been incredibly surprised. I don't have anything to compare it to...but the damn thing seems to breathe really well.
OP
OP
Given the "morning hot laps" and burnouts I'm saying no
Even with the hot laps...I'm getting better gas mileage. Although...I am running premium fuel now...sooooooo it probably evens out.
Nice! 17-19mpgs is what ive heard before for these swaps.the 5.3 is a great motor. Not like the 6.0l i put in my 70 k20. It gets 10-15.
Its an lm7 right? Stock cam and heads? I'm guessing the premium fuel is to help play it safe and let you get more agressive with timing?
OP
Yes, it’s an LM7 with stock heads and it has an upgraded cam in it that’s makes power in the 1800-6000 range. I’ve got the fuel cut off set to 6000, because honestly, the stock TJ gauge only goes that high…so meh.
I haven’t gotten brave enough to start playing with the timing yet, but I also wasn’t brave enough to drop the clutch and spin the tires in the beginning…and here we are.
Soon enough…fuel/air is nearly dialed in, so spark will be next to squeeze more power out.
Are you using HP Tuners? I have a LS swap going on a C10 and will eventually need to tune it. I haven't researched this stuff for a while. I've done some stand alone GM TBI stuff in the past.
Just as a FYI, when you start adding timing, it will effect you AFR. Not a lot, but enough to have to revisit it. Generally more timing will want more fuel. Which is a good thing because that all means more power!
Just as a FYI, when you start adding timing, it will effect you AFR. Not a lot, but enough to have to revisit it. Generally more timing will want more fuel. Which is a good thing because that all means more power!
OP
I actually went the open source/free software route…which has been frustrating most of the time, but has forced me to learn about the changes I’m making instead of watching videos, making changes, and crossing my fingers. It’s not for everyone, and maybe I’m just a slow learner, but it hasn’t been too bad and I’m more confident in the changes I’m starting to make and seeing the results of my persistence in understanding it all. I actually just got all the formulas down in excel to be able to create those fancy histogram tables as seen in nearly every HP tuner video - it’s so freakin easy to log and tune now. I use PCM hammer/logger with Tuner Pro RT and a OBDX Pro VT tool. If you need help when it comes time, let me know.
Or just spend $500ish dollars having someone else tune it if you are never going to tinker with it anyway…costs the same to buy the HP Tuners package.
I'm pretty decent with TunerPro, that's what I used on my 3 TBI projects.
I may hit you up in the future.
Thanks
I may hit you up in the future.
Thanks
Is this thread still kicking? I've done a 6.0 LS2 swap in my 05 LJ making it a ton of fun but still ironing out some details. Specifically the Jeep PCM is finicky only running the AC sometimes and never the cruise control. I bought a reprogrammed PCM from Wranglerfix which works fine in his TJ but not well in mine. Any other sources for reprogramming the Jeep PCM?
OP
Jeep PCM running the AC? How did you route that? I ran a line from the ground signal of the selector that goes back to the PCM to trigger the relay for 12v AC request to the PCM, and then the PCM fires a ground to another relay that sends 12v to the compressor as long as my cycling switch is also grounded.
I’m about to attempt removing CEL codes from mine that no longer apply using HP Tuners. They just released some software that can read/write to this era PCM. License for the VIN is only $50 if you’ve already got a OBD2 tuner module.
Longhorn84
TJ Enthusiast
I use the Jeep PCM to control AC, video here:
I do still need to figure out how to turn off the Jeep check engine light, anyone know?
Main thing I'd like to improve is the throttle response, I have good response it seems from 1-2k rpms but then if I push the gas down it shoots up and just doesn't feel smooth at all, maybe that's the 4 speed or my gearing but long term I'd love to fix. Everyone who I tell about my jeep asks if it's fast, the answer is it's certainly faster than the 4.0 but it's far from a speedster with a stock 5.3 and stock 4l60e, 4.56 gears and 35" tires. Anyone with a similar LS swap think their TJ is "fast" or "quick"?
I do still need to figure out how to turn off the Jeep check engine light, anyone know?
Main thing I'd like to improve is the throttle response, I have good response it seems from 1-2k rpms but then if I push the gas down it shoots up and just doesn't feel smooth at all, maybe that's the 4 speed or my gearing but long term I'd love to fix. Everyone who I tell about my jeep asks if it's fast, the answer is it's certainly faster than the 4.0 but it's far from a speedster with a stock 5.3 and stock 4l60e, 4.56 gears and 35" tires. Anyone with a similar LS swap think their TJ is "fast" or "quick"?
OP
Mine is insanely fast. I can pull on my son when he’s driving my Ram with a 400hp+ Hemi. I have 4.10 gears and 33’s tho.
Did you ever modify your tune? Or did you go straight stock? I watched all your videos multiple times over before I began my swap and I think you stuck to stock everything. A tune can definitely help with your throttle response.
HPTuners just released an update to read/write JTEC ECMs…so you could turn off the diagnostic codes that are popping up that cause the CEL. I still haven’t done it on mine because the software is still in beta and that kinda freaks me out.
Did you ever modify your tune? Or did you go straight stock? I watched all your videos multiple times over before I began my swap and I think you stuck to stock everything. A tune can definitely help with your throttle response.
HPTuners just released an update to read/write JTEC ECMs…so you could turn off the diagnostic codes that are popping up that cause the CEL. I still haven’t done it on mine because the software is still in beta and that kinda freaks me out.
Longhorn84
TJ Enthusiast
Good to know. Novak did modify my ECM but I really have no idea what they did to it so maybe the answer is at least I should try the tune.
Didn't you put a decent cam in yours?
is it shifting at too low of an rpm?
What about the power enrichment delay? Eliminating that will make quite a difference compared to stomping it and then waiting for the pcm to finally go rich.its a long time.