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4L60E Misbehaving on the highway - Drivability
First time using the HP Tuner and have done some homework so will try to explain what is happening and what I know.
Trans is rebuilt and all parts have been checked out by two transmission shops. Both say the trans is doing what it is commanded, when it is commanded and no code or issues are noted.
When on the highway the TC drops out of lockup at the slightest downhill at 70 MPH. I have put my cheapo reader on it and the TPS is reading about 20% when it drops out of lockup and then locks back up at about 25%. That causes a lot of lock and unlock cycles on a long trip and is just not normal.
I pulled my TCC Apply/Release tables and I don't see anything that says it should be commanding that way
Attachment 144148
As I understand it, this says that the 4th Apply at highway speeds should lock up the TC between 53 and 59MPH for any throttle position under 43.8 percent and once I hit 75 it should stay locked at any TP under 50%. The unlock throttle positions are up in the 70 - 80% ranges.
Any ideas why this might be happening? I will go take a drive and see if I can log when it happens.
Parts replaced and cleaned///
New TPS
New MAF
Cleaned Throttle Body
New TCC Solenoid and harness
New Torque converter and valve body (OE spec replacements from TransStar)
Trans is mildly built, z pack clutches, hardened shells, wide band, larger boost valve, PWM not blocked
Thanks in advance, have a long trip planned and was hoping to square this away this week but this was unexpected. :banghead:
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Tested TCC PWM Lock/Unlock
Thanks for the replies so far, it's given me some things to work out and a few more ideas.
Tonight I drove it with the following manually commanded on
Attachment 144186
While I had the TCC PWM Lock/Unlock toggled Green on the On button the trans acted completely normal. No weird behavior on the highway at all, trans locked up cruising at 70 and no big slip going down hill.
I toggled the on button off (but not the Off button on), both grey and ran it down some hills and it went back to the bad behavior. If I toggled the on button while the trans was slipping on a down hill, it immediately stopped slipping.
Unfortunately, my laptop died on the way home and I lost the logfile.
Now the question, what does this mean? Can I/Should I tune it to run this way all of the time? Shouldn't it already run this way? Honestly, the trans felt freer and smoother throughout the whole drive with that toggled on.