Yanked 4l60 BLOWS 3-4 AGAIN
Rebuilt it again, turned off the misfire tables, Same thing, same time frame. Unlocked converter....then slipped, then junk, burned 3-4 again. Any tuning issue I have missed maybe?
Thanks
Slipping 3/4 clutch pack has the same feel as the converter clutch would if it was slipping.
You might look to one of the transbuilders listed here --------------->
Rebuilt it again, turned off the misfire tables, Same thing, same time frame. Unlocked converter....then slipped, then junk, burned 3-4 again. Any tuning issue I have missed maybe?
Thanks
What 3-4 clutch are you using? What clearance are you setting it up at?
When it's fresh rebuilt does it slide into 3rd? Does it tie up on the 2-3 shift?
I've given this advice before, I've had the problem myself, I've tuned a few other cars with this problem.
Do as you will, I'm not going to beg you or try to convince you.
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The same issue? Drives for an hour then starts to slip, then burns out the transmission?
P0757 P0751
"What happens is the PCM comands a gear then compares the ENGINE RPM to the OUT PUT SPEED. Because of the high stall of the cam the PCM sees the RPM are to high and assumes the shift did not occur and set a code for the solenoid being faulty when it actually is not"
I cannot see this being an issue when on the highway for an hour, the car has not shifted in an hour, the codes do not come up in the PCM ever, not even in history, but I will delete them anyway.
The Best V8 Stories One Small Block at Time
and whether you are getting slip in the frictions (not
TCC). Stock pressure profiles are meant for base torque
levels (1.8 STR stock converter) and fuel economy.
You go downshifting into the shift extension at high
torque multiplication, you could overwhelm the friction
torque capacity and scrub them real good.
At cruise especially, the applied pressure is low. Add to
this any cleverness like a MAF or speed density tune
that reads low on airflow -> "load", and you starve the
line at mid throttle too. Take a look at Delivered Torque
- Trans. If it seems lower than you think is realistic, that
could indicate an airflow accuracy problem that can lead
to line pressure shortage.
So anyway you should be looking at input and output
shaft RPM, and criticize that ratio against the trans current
gear ratio. You can watch how it pulls in to 1:1 across a
shift, to gauge whether it's getting done quick or not (too
long and slow, increases heat dumped inside the clutch
pack or the band) and you sure do not want to see anything
but straight-up gear ratio when in gear (anything else says
hard slip).
I massaged my force motor table long ago to up the 0% line
column (bring current down) and pressure is all in by 300 lb-ft.
That Force Motor table also is indexed by trans fluid temp.
If the problem comes in after long running, have you checked
the reported temp? Need more cooling? I flattened that dimension
in the force motor table too, because I didn't understand or trust
the GM profile and sure did not want any more blowoff at hot,
than cold.
The thing is we have done this same set up a dozen times, same trans, same converter, same tune, same cooler. Of course my wifes car is giving me a headache (better than a customer I guess) Funny thing is, she is so short I don't even think that she car floor it....LMAO. When i get it back in, I will drive it myself and start digging I guess....thanks for the replies!
I cannot see this being an issue when on the highway for an hour, the car has not shifted in an hour, the codes do not come up in the PCM ever, not even in history, but I will delete them anyway.
When he got to my house he had three DTC's that would disable lock up.
Misfire, 751, 757.
I did some standard transmission tuning and he replied back that the problem went away.
In your case you seem to have tuning equipment, why don't you set it up to log at the least tcc lock up and drive it. Whats your trans temp?
I've been through the same thing, blame the converter manufacturer, why don't you supply tuning instructions, etc.
97% of my posts and reading on this site are in the transmission section. I see the same thing over and over with torque converter tuning and I've learned that it's not very difficult to do.
I realize it's dificult for me to be 100% correct not having the car in my possesion, but your problem sounds very familiar.
When he got to my house he had three DTC's that would disable lock up.
Misfire, 751, 757.
I did some standard transmission tuning and he replied back that the problem went away.
In your case you seem to have tuning equipment, why don't you set it up to log at the least tcc lock up and drive it. Whats your trans temp?
I've been through the same thing, blame the converter manufacturer, why don't you supply tuning instructions, etc.
97% of my posts and reading on this site are in the transmission section. I see the same thing over and over with torque converter tuning and I've learned that it's not very difficult to do.
I realize it's dificult for me to be 100% correct not having the car in my possesion, but your problem sounds very familiar.
Yank builds converters. Damn good ones. He built mine. He doesn't tune. TUNERS tune cars. Either learn to tune, as setting up the tune for a converter is very easy. I own hpt pro and do my own tuning. Or take it to a tuner and let them.
Would you tell your engine builder you want a start up tune?
You want to build cars? Learn how. You want someone else to build it for you? Pay them to.
Yank builds converters. Damn good ones. He built mine. He doesn't tune. TUNERS tune cars. Either learn to tune, as setting up the tune for a converter is very easy. I own hpt pro and do my own tuning. Or take it to a tuner and let them.
Would you tell your engine builder you want a start up tune?
You want to build cars? Learn how. You want someone else to build it for you? Pay them to.



