Lockup issues?

[Yngwytprik]

1998 2 door 4x4 tahoe. 5.7 4l60e. 168k. All stock engine and trans. Thing runs great, and 90% of the time drives great as well. But it seem anywhere between 40-50 mph typical cruising throttle its in and out of lockup repeatedly. Any speed over 50 and it stays in lockup just fine. Trans shifts smooth through all the gears and lockup is nice and smooth as well unless im in the 40-50mph range. Then its in and out in and out unless i get goin past 50mph. Any ideas? Oh and figured id add it doesnt feel at all like a jerk or missfire like a tc issue its smooth in lockup and smooth out of lockup over and over.

 

[1952Chevy]

I just discovered today that the Torque Pro app can read input/output speeds for the transmission, Torque convertor clutch slip etc. Cheap solution to verify that is in fact what is happening.

If that is what is happening it sounds like a pressure/solenoid issue. From my understanding the TC lockup is driven by fluid pressure in the trans. Not super familiar with the innerworkings of the 4l60s though, just a guess. How's your fluid level?

 

[Yngwytprik]

I just discovered today that the Torque Pro app can read input/output speeds for the transmission, Torque convertor clutch slip etc. Cheap solution to verify that is in fact what is happening.

If that is what is happening it sounds like a pressure/solenoid issue. From my understanding the TC lockup is driven by fluid pressure in the trans. Not super familiar with the innerworkings of the 4l60s though, just a guess. How's your fluid level?

Fluid levels good, clean red, and doesnt smell burnt

 

[Yngwytprik]

I just discovered today that the Torque Pro app can read input/output speeds for the transmission, Torque convertor clutch slip etc. Cheap solution to verify that is in fact what is happening.

If that is what is happening it sounds like a pressure/solenoid issue. From my understanding the TC lockup is driven by fluid pressure in the trans. Not super familiar with the innerworkings of the 4l60s though, just a guess. How's your fluid level?

And i guess the torque pro app your talking about is an android only app? I cant find it on iphone.

 

[1952Chevy]

And i guess the torque pro app your talking about is an android only app? I cant find it on iphone.

Ah yes it is, I believe you should be able to read that info with Dashcommand which is available on apple. I am not familiar with that one though. Either way you will need a bluetooth OBD II Reader less than 30 bucks on amazon.

 

[Yngwytprik]

So i was underneath it poking around and found this red 2 wire plug and i have no idea wheee it goes. Cant find a home for it anywhere. (Yes im aware the front mains leaking ill get to it) anyone know what that pigtails for?

 

[letitsnow]

45-50 mph is where the tcc typically locks. Not sure that anything is wrong, if you are trying to drive at that speed. Maybe pull the shifter down to 3rd and drive?

 

[PlayingWithTBI]

On my 700R4 I have it set up to lock @45 MPH and unlock @40 MPH in either 3rd or OD. This way it won't lock/unlock all the time when driving around those speeds. Maybe your 4L60E has the same option in the PCM?

 

[Yngwytprik]

45-50 mph is where the tcc typically locks. Not sure that anything is wrong, if you are trying to drive at that speed. Maybe pull the shifter down to 3rd and drive?

Ive never had one repeatedly go in and out at a steady speed before. When its goin in and out of lockup over and over i can hear the rpm and see it come out of lockup and go up about 200 rpm and back in dropping about 200 rpm and it doesnt stop as long as im holding a steady speed. But i did notice this morning it didnt do it at all until the truck was completely warmed up miles down the road.

 

[Yngwytprik]

On my 700R4 I have it set up to lock @45 MPH and unlock @40 MPH in either 3rd or OD. This way it won't lock/unlock all the time when driving around those speeds. Maybe your 4L60E has the same option in the PCM?

I think with a custom tune but im not sure. I have more experience with carbs and kickdown cables then i do these vortecs and 4l60 electronic crap.