Massive Lean Spike on Shifts
Thread Starter
Joined: Jan 2011
Posts: 1,921
Likes: 80
From: North Houston
Massive Lean Spike on Shifts I have a driveability issue with my LS swapped Hombre, maybe y'all can help. Ever since I swapped the 383 LS6 and T56 magnum from my Camaro into my 2000 Isuzu Hombre, it spikes really lean when I shift. It was so bad the other day I had to roll backward down a hill so I could get a running head start on the hill. Why didn't that happen in the Camaro? Well, the Camaro was always in open loop. One of the goals of the swap was to finally put it in closed loop. Also, idle was erratic in the Camaro... I'd have to tap the throttle going to a stop to make sure it didn't die. So, I got a mail order tune and things got better. The truck doesn't want to die when going to a stop, and I can definitely see the O2 sensors switching (on the wideband) when driving.
However, the lean spike is literally debilitating. It's most prominent when cold after the computer warms enough to go into closed loop. As it heats up from 120 to 190, the spikes shorten and the absolutely crippling stumble reduces, but it's still there and if I don't put a little throttle in it between shifts, it falls on its face.
The support asked for a log file. I have HPTuners, they had me log in EFILive. but did nothing with the files when I gave them to him. So, I'm attaching them to see if y'all can find something I can touch. Any insight would be appreciated!
Here's what the motor has:
383 LS6 bottom end
230/236 .602/.602 111LSA
Patriot Stage 2 heads
Fuel Injector Connection LS2 52# injectors
Aeromotive regulated at 58#, 8AN supply
FAST LSXRT Vengeance ported
102 NW TB by cable
4" intake with LS7 MAF (closed loop S/D)
10% UD
1 7/8" Stainless Works long tubes, 3" dual exhaust
However, the lean spike is literally debilitating. It's most prominent when cold after the computer warms enough to go into closed loop. As it heats up from 120 to 190, the spikes shorten and the absolutely crippling stumble reduces, but it's still there and if I don't put a little throttle in it between shifts, it falls on its face.
The support asked for a log file. I have HPTuners, they had me log in EFILive. but did nothing with the files when I gave them to him. So, I'm attaching them to see if y'all can find something I can touch. Any insight would be appreciated!
Here's what the motor has:
383 LS6 bottom end
230/236 .602/.602 111LSA
Patriot Stage 2 heads
Fuel Injector Connection LS2 52# injectors
Aeromotive regulated at 58#, 8AN supply
FAST LSXRT Vengeance ported
102 NW TB by cable
4" intake with LS7 MAF (closed loop S/D)
10% UD
1 7/8" Stainless Works long tubes, 3" dual exhaust
Interested to see how you make out.. i have a similar build:
408
t56 magnum
Mamo 235's
241/246 on a 113+1
In my 92 extended cab s10!
I litterally just got mine driving and idling thebother day. Im using efi live. I have similar things going on.
Im using an 01 f body 6 speed tune. I copied the main VE map and cranking VE from a 6.0L van... and some other stuff.... i can share my tune if it would help u out when i get to my pc.
408
t56 magnum
Mamo 235's
241/246 on a 113+1
In my 92 extended cab s10!
I litterally just got mine driving and idling thebother day. Im using efi live. I have similar things going on.
Im using an 01 f body 6 speed tune. I copied the main VE map and cranking VE from a 6.0L van... and some other stuff.... i can share my tune if it would help u out when i get to my pc.
Thread Starter
Joined: Jan 2011
Posts: 1,921
Likes: 80
From: North Houston
Nope, I logged it but didn't post it up. I ended up selling it before it was resolved, but the primary suspect was injector data. Setting it in open loop did help, so there's that.
TECH Fanatic
Joined: Oct 2014
Posts: 1,220
Likes: 179
From: Virginia
Guess I'll throw in my 2 cents here for some that also have this problem for ideas, since you sold it already.
The first thing that I would suspect is Decel Fuel Cut Off, DFCO. After that, VE, then MAF. Injector data, perhaps, but you can always ADD fuel to the VE and MAF. Simply re-tuning it probably would of resolved this, in the normal order. One of the first things you do is disable DFCO and trims, then tune the VE, MAF (if needed, non SD cars) and then spark. Also, under 4k rpm (stock setting) the computer biases VE, even on older cars and more so on newer ones. So that could of been just a bad VE tune to start, as RPM's drop and so forth. Injector data is also definitely something you want to get right as well, but surprisingly, can be adjusted for in other places if it's not 100% correct, like on the VE table, which is honestly more important than the data.
I've even had to change my injector settings to correct an opposite problem when running speed density. Reducing the min pulse width enough to allow it to actually not be 20% rich all the time in decel situations. Injector Connection even said that's about the only thing you could do, and it was with their data. You could of had either the opposite problem with you minimum puslewidth, but more likely it was on the VE table since you can always just increase the number which will open it longer. This isn't as bad as when you've reduced the VE cells to beyond the minimum PW, which at that point you get what you get and VE numbers do nothing. Hence reducing the min PW until you can correct it on the VE table.
The first thing that I would suspect is Decel Fuel Cut Off, DFCO. After that, VE, then MAF. Injector data, perhaps, but you can always ADD fuel to the VE and MAF. Simply re-tuning it probably would of resolved this, in the normal order. One of the first things you do is disable DFCO and trims, then tune the VE, MAF (if needed, non SD cars) and then spark. Also, under 4k rpm (stock setting) the computer biases VE, even on older cars and more so on newer ones. So that could of been just a bad VE tune to start, as RPM's drop and so forth. Injector data is also definitely something you want to get right as well, but surprisingly, can be adjusted for in other places if it's not 100% correct, like on the VE table, which is honestly more important than the data.
I've even had to change my injector settings to correct an opposite problem when running speed density. Reducing the min pulse width enough to allow it to actually not be 20% rich all the time in decel situations. Injector Connection even said that's about the only thing you could do, and it was with their data. You could of had either the opposite problem with you minimum puslewidth, but more likely it was on the VE table since you can always just increase the number which will open it longer. This isn't as bad as when you've reduced the VE cells to beyond the minimum PW, which at that point you get what you get and VE numbers do nothing. Hence reducing the min PW until you can correct it on the VE table.
