2 Attachment(s)
Anyone feel like checking out this ongoing (3+ years) surge issue? Log/ tune inside
Howdy! We have had an ongoing issue with a surge in the 1500-2200 RPM area for years in this 70 Chevelle I put together some years back. Have had a few issues resolved over the years and two different tuners check it over and we have made some progress and some not so much. Started to recently get somewhere with pulling back some throttle cracker and follower stuff and that seemed to help. The included tune I copied and pasted some throttle cracker and follower tables from another tune and honestly its real bad now. I need to go back to how it was but I figured I would get something up here so someone with far more knowledge than me could at least maybe check it over and give their thoughts. At this point the real low throttle is very bad and its hard to drive as you let out the clutch its a lot of work and nowhere near smooth. As I said we have had it better with other tunes in that area at least with just the cracker and follower changes. If you look at the log you can see the squiggly RPM lines a handful of times where it changes about 2-300 RPM over and over and even changed 2-3 MPH at times. The surge is always at very low throttle, around 6% and under and has been there and hard to get out of it.
Engine is CRATE 454 LSX with sheetmetal LS7 style intake and stock GM LS7 injectors. Trans is T56, gear is 4:30. I know this setup will never drive smooth as silk but still looking for more than it has. Never much of an issue in gears above 3rd, pretty much always been a pain while taking off/ shifting/ 30ish MPH cruising under light load.
