Torque converter not locking 1995

[aboatguy]

Torque converter not locking even at steady highway speeds. Cruise control still works so does that eliminate the brake switch or are there separate brake switch circuits for the cruise control and torque converter lock up?

 

[blackxpress]

Is it a 700R4? If so, the most likely suspect is the lockup solenoid. I'm pretty sure the lockup circuit is wired through the brake light switch. If your brake lights are working, the chances are that isn't your problem. It could be something as simple as a loose electrical connector. If you drop the pan you can check that before you actually replace the solenoid. Or, you can take it to a transmission shop. They can hook up a scan tool, test drive it and be pretty certain what's causing it. The scanner will tell them whether or not it's calling for lockup and whether or not the brake switch is working properly. If so, that rules out the brake switch and TPS. The only thing left is the lockup solenoid and associated wiring.

 

[redvett]

1995 is a 4L60E take a data scanner and watch as someone drives and see if the PCM enables TCC if so then its the TCC solenoid.

 

[aboatguy]

Looks like TCC is enabled however, slip rpms have been stupid high and tapping brake at speed doesn't cause an rpm jump. I believe I may have smoked the converter clutch (i've been chasing a vibration/shudder too)
Since the shudder was noticed after a LT4 dash install I was trying to see if it was something under there.
mike

 

[redvett]

1993 & up are PWM (pulse width modulated? and the PCM controls the application during the driving cycle. You should watch what the PCM is doing when it is applying/unapplying but you may a bad converter.

 

[aboatguy]

does data master log that?

 

[aboatguy]

Converter should be locking but its not. Is it converter, solonoid or wiring? Seems to me that the PCM would note problem with circuit so mechanical issue (converter ???)

http://i14.photobucket.com/albums/a342/aboatguy/postthis.jpg

 

[aboatguy]

1993 & up are PWM (pulse width modulated? and the PCM controls the application during the driving cycle. You should watch what the PCM is doing when it is applying/unapplying but you may a bad converter.

I forgot I had this posted on here, so to resolve it in case some one does a search in the future. It was the torque converter.......

 

[vetteoz]

It was the torque converter.......

This is why some trans builders recommend doing away with the lockup in Hi-Po apps .The clutch is intended just to lock the convertor parts up ; not take full torque under load.
Personally I have never understood why someone with a 500Hp engine and big convertor is worried about the fuel economy.The risk of the clutch taking a dump and putting debris through the trans is not worth it.

What did you do to " I may have smoked the converter clutch " ?

 

[aboatguy]

This is why some trans builders recommend doing away with the lockup in Hi-Po apps .The clutch is intended just to lock the convertor parts up ; not take full torque under load.
Personally I have never understood why someone with a 500Hp engine and big convertor is worried about the fuel economy.The risk of the clutch taking a dump and putting debris through the trans is not worth it.

What did you do to " I may have smoked the converter clutch " ?

It was an aftermarket high stall converter.

I did another (higher HP Head cam install AI 200s and custom cam to replace AI 190s and 280XFI) supporting mod changes too.


Long story short engine felt soft at the top of second and third (drive) and I was chasing the problem (ended up needing a bigger fuel pump)

On the second datalog with new fuel pump (ed wright was sending new tunes after each data log) I noticed high converter slip rpm and vibration.
I actually broke the converter, when I pulled the converter, I could hear pieces sliding around loose inside it (I'm guessing one or more fins were broken).
The irony is I built a 355 vice 383/396 IOT move the power band up the rev range IOT help minimize breakage and to help with off the line traction and I failed miserable on both counts.
However, I can't give enough KUDOS to: Ed Wright, Brian Ebert and Ron/Phil Odom in my honest opinion they ROCK and provide outstanding service/performance for the money!

As for your comment about not worrying about the converter locking. I spend most of my time on the highway and with converter locked my transmission, oil and coolant temps are much cooler. (on hot summer days as much as 20-30 degrees cooler ) My 3500 vig actually feels tighter around town than the 2800 Midwest did


Mike