79 Trans Am LS3/TR6060 swap

[Joepeinado]

Hello all,

I've been a long time lurker and reader and have picked up some knowledge on tuning. I have done a couple of cam swaps and street tunes that have turned out good. I currently have a 79 T/A that I I've been tuning for the last month (take it to work and back) and have nailed done quite a few things, but I am stuck on something that I cant figure out. I have tuned the MAF with a wideband and for the most part the majority of the table is within -1/-2 fuel trims and works extremely well while in OPEN LOOP. Soon as I throw it back to closed loop, that thing starts to develop a stutter/miss/cough (whatever you wanna call it) on part throttle and just feels doggish overall. **Feels like its either lacking fuel for that moment** I have messed with the VVE as well, and there is a spot that always leans out real bad on WOT and when I add fuel, the difference is way to much compared to the cells around it. For now, I want to nail down the open loop/closed loop deal first. Don't have any other issues, car idles great and have no surging, just that stutter, miss, lack of balls feeling on part throttle in closed loop. Messed around with the 02 switching as well, I have attached the tune and a file. Ready for all the criticism, bet I still suck LOL

***file for evening run, I switched to open loop almost 3/4 way towards the end***

E38 ECMmost current tune.hpt2-2-23 EVENING.hpl
L99 to LS3 conversion
F35 CAM
Speed engineering LT headers
No cats
Xpipe
stock injectors
stock intake
stock TB
supporting mods for cam (lifters, trunnion, etc)
TR6060 to T56 tails haft conversion

[kevin87turbot]

Hello all,

I've been a long time lurker and reader and have picked up some knowledge on tuning. I have done a couple of cam swaps and street tunes that have turned out good. I currently have a 79 T/A that I I've been tuning for the last month (take it to work and back) and have nailed done quite a few things, but I am stuck on something that I cant figure out. I have tuned the MAF with a wideband and for the most part the majority of the table is within -1/-2 fuel trims and works extremely well while in OPEN LOOP. Soon as I throw it back to closed loop, that thing starts to develop a stutter/miss/cough (whatever you wanna call it) on part throttle and just feels doggish overall. **Feels like its either lacking fuel for that moment** I have messed with the VVE as well, and there is a spot that always leans out real bad on WOT and when I add fuel, the difference is way to much compared to the cells around it. For now, I want to nail down the open loop/closed loop deal first. Don't have any other issues, car idles great and have no surging, just that stutter, miss, lack of balls feeling on part throttle in closed loop. Messed around with the 02 switching as well, I have attached the tune and a file. Ready for all the criticism, bet I still suck LOL

***file for evening run, I switched to open loop almost 3/4 way towards the end***

E38 ECMmost current tune.hpt2-2-23 EVENING.hpl
L99 to LS3 conversion
F35 CAM
stock injectors
stock intake
stock TB
supporting mods for cam (lifters, trunnion, etc)
TR6060 to T56 tails haft conversion

It looks like it's very slow to correct the fuel trims. Have you tried setting the Fuel trim and oxygen sensor tables back to stock?

[Joepeinado]

I have not, but when they were stock, I had the same issue. I started reading a thread that has something to do with "02 tuning" and modified the tables. Guess they're moving slower? I noticed that my last log had really lean numbers

[Joepeinado]

Went to stock 02 sensor settings. I'll flash it in the morning and log another run

[Pekka_Perkeles]

I can't check your logs (I have older software) but as this is swap, make sure your O2's aren't crossed.

[Joepeinado]

Checked 02 location, when unplugging bank 1, it throws a code for bank 1. They're located in the proper section. I will upload today's run and the last maf run in open loop to compare

[blindsquirrel]

Man, idle spark is going nuts. Bounces from 3.5 to 28 to 3.5 to 28 to 3.5...

I don't know if that one big block calling for 28* over such a large area, in both the idle & main spark tables, is the best idea. Same for the changes made to over/underspeed corrections - the stock settings are much lower, and more progressive, and with a cam you usually want less than stock in there, not lots and lots more.

[Joepeinado]

I did mess around with the over/under speed, will put it back to stock.
My issue is on part throttle-WOT. It coughs, stutters a bit and then picks up again, but wont do this when in open loop.
cam size is 235/248 .649/615 111 LSA, 109.5 ICL, What would a ballpark idle timing be at? Thought the bigger the cam, the more spark it might need.

I've read that spark should be the same on all spark tables to have a better or smooth transition. Ill put some of these back to stock and see how it behaves.

[Joepeinado]

for whatever reason, it wont let me upload the file now. File might be bigger than the allowed size, but here are some screenshots of the MAF values that are currently in my tune. They all check out fine but if you see my log in the first post with the 02's active, its running real lean.

[Joepeinado]

Here is my evening log on the way home and the changes I made on the tune.
put back stock 02 settings along with some timing that was mentioned before.
the hesitation is still there though, did it a couple of times around 40-50% throttle, and the one I remember seeing was around the 00:16:40 mark through 00:17:15, around that area. Still leaning out bad on some areas again, not sure how this happens if the MAF calibration was on the rich side. Any more pointers?

would this be injection timing?
I haven't messed with the torque tables either.

[Joepeinado]

Anyone else that can chime in? I added 15 to the torque tables and it helped a lot. Stutter isn't as present. Not sure if that helped or not