5.3L-based 383 tuning assistance/advice

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12-02-2016
Batmanntexas

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5.3L-based 383 tuning assistance/advice

Hello! Thanks in advance to all of the knowledgeable folks who go above and beyond to help other folks out, here on the forum. I will do my best to present my tuning issues in the most logical manner.

First off, I have attached the current ECM tune file uploaded in the truck, a 2007 Avalanche, along with the most recent log from tonight. The stock file is included, because I flashed in the stock TCM file to see if there would be a difference in tranny performance.

The motor has about 30 miles on the fresh rebuild. Rebuild consisted of forged rotating assembly, 3.905"x4", 12:1CR, max effort porting job on stock 243 head castings (315cfm intake flow .600", 301cfm exhaust flow .650"), cam is a 239/247/.623"/.649" on 112LSA, ported stock truck intake, ported LS3 TB, LT headers, no cats, and a 3200RPM Circle D stall converter in an otherwise stock 4L60E. Now, on to the issues I'm experiencing.

1. Upon startup, cold or hot, the motor flares to about 2200RPM, holds this for 3-5 seconds, then settles down to 900-ishRPM. I believe it may have to much air, but not 100%.
2. When driving the truck in a normal manner, 25-35% ETP, the truck behaves like it has a CVT transmission, no definitive gear changes,just a gradual rise in speed to an almost constant engine RPM (2000-2200ish)...it's really weird, however if you shift it manually, it behaves normally.
3. The TCC is not locking up with any consistency, whatsoever.
4. Around 2800-3200RPM, under light-to-moderate load the engine breaks up, however there isn't any KR or obvious fuel/timing issues that I could see, or my buddy, who was trying to help out.
5. Once you go WOT, the converter seems to flash, the truck starts to pull like a monster until about 5200-5500RPM, at which point it starts bouncing between 5500-6500RPM, almost like you were slipping a clutch in and out. You can see this manifestation in the attached log file, about the 3/4 point in the log, IIRC.

Also, ignore the WB reading, as it had been disconnected at this point.

The log file is with the stock transmission tune BTW.

Thanks again,
Scott
12-03-2016
Batmanntexas

So, doing further research, the popular belief is that my stall converter will act similar to a CVT during light-to-moderate throttle application. So, the only issue now is what is causing my TCC lockup problem, and causing the high RPM behaviors.
12-03-2016
GHuggins

Google - Search - Bluecat transmission tuning tool with HP tuners... Should hopefully lead you to the tool for tuning transmissions for stall converters...

Normal feel with light cruise - you can up the pressures slightly to help with this - you'll hear it shift more than feel it...
12-05-2016
Batmanntexas

Quote:

Originally Posted by GHuggins

Google - Search - Bluecat transmission tuning tool with HP tuners... Should hopefully lead you to the tool for tuning transmissions for stall converters...

Normal feel with light cruise - you can up the pressures slightly to help with this - you'll hear it shift more than feel it...

Thanks for the feedback. I found BlueCat's transmission tuning tool, and it works AWESOME! So, I got that pretty much dialed in now. The high RPM converter flaring turned out to be......ahem....low fluid!

Still working out some idle and part throttle tuning issues, but she's coming together.

Thanks again,
Scott