ls1 runs rough while in O/D
02-25-2018, 12:59 PM
#1
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ls1 runs rough while in O/D
2003 50th Auto
Engine is throwing no Codes. When driving between 45 and 55 MPH, the engine jerks minimally and tach moves 4-5 RPMs. If I hit accelerator, no problem, when it downshifts. I am leaning towards a fuel filter, but, any help would be greatly appreciated.
Engine is throwing no Codes. When driving between 45 and 55 MPH, the engine jerks minimally and tach moves 4-5 RPMs. If I hit accelerator, no problem, when it downshifts. I am leaning towards a fuel filter, but, any help would be greatly appreciated.
03-17-2018, 02:12 AM
#3
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St. Jude Donor '13-'14-'15
Any misfire whether real or false will lock/unlock the TQ converter---Many mods will create false misfires especially cams rockers or headers However this is all correctable with tuning
ALSO GM shorts shifts the trans into 4th gear way to early and also locks the TQ converter way to early (like at 38 MPH) this makes the engine LUG too much in 4th gear and has the potential to buck at low RPM's
Trans tuning can fix this Typically GM locks the converter at 38 MPH in 4th gear This is horrible
On my tunes I lock the converter only once it is on the freeway like 55 MPH And I delete the 3rd gear lockup entirely-----This will prevent the lugging at slow speeds in 4th and 3rd at low RPMs I set the lock up minimum in 4th gear to about 55 MPH ( basically when on the freeway) and also raise all the shift points about 2-4 MPH higher depending if your car has a 2.73 or a 3.15 rear gear
1st figure out if you are getting a misfire code (p0300) If so that requires another fix--- IF it is a false misfire-It requires tuning-If it is a real misfire then the fix is obvious--plugs wires or coils ( rarely a clogged injector)
ALSO GM shorts shifts the trans into 4th gear way to early and also locks the TQ converter way to early (like at 38 MPH) this makes the engine LUG too much in 4th gear and has the potential to buck at low RPM's
Trans tuning can fix this Typically GM locks the converter at 38 MPH in 4th gear This is horrible
On my tunes I lock the converter only once it is on the freeway like 55 MPH And I delete the 3rd gear lockup entirely-----This will prevent the lugging at slow speeds in 4th and 3rd at low RPMs I set the lock up minimum in 4th gear to about 55 MPH ( basically when on the freeway) and also raise all the shift points about 2-4 MPH higher depending if your car has a 2.73 or a 3.15 rear gear
1st figure out if you are getting a misfire code (p0300) If so that requires another fix--- IF it is a false misfire-It requires tuning-If it is a real misfire then the fix is obvious--plugs wires or coils ( rarely a clogged injector)
03-19-2018, 11:51 AM
#4
Racer
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I just swapped my ls1 for an ls3 crate motor. During the swap I lost some atf from disconnecting but thought it was negligible. After getting a tune I had minimal surging like you describe. I checked atf and had to top off, this fixed the small surging now I only have the lugging from tc locking/unlocking as described. I’ve gotta get into the tune a fix it as stated above.
03-28-2018, 03:03 PM
#5
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St. Jude Donor '13-'14-'15
I just swapped my ls1 for an ls3 crate motor. During the swap I lost some atf from disconnecting but thought it was negligible. After getting a tune I had minimal surging like you describe. I checked atf and had to top off, this fixed the small surging now I only have the lugging from tc locking/unlocking as described. I’ve gotta get into the tune a fix it as stated above.
GM also locks the converter in 3rd gear at 28 MPH with the same issues as the 4th lock up
When tuning an auto trans I always DELETE the 3rd gear lock/unlock entirely Then in 4th gear I raise the minimum lock up only when you are on the freeway --Like 50-53 MPH-----This always eliminates the low RPM bucking---
