Converter is not locking scans/datalog show no codes looks like converter should lock but slip rpm high. Is it tranny or converter?
Seems like it should be locked here.
[IMG][/IMG]
Just to show that the brake switch/engaged and enabled circuits change

 

Could be any of several things, Converter, Input shaft oring. TCC valve, PWM solenoid, Converter control valve.
Gonna be a little bit of a which hunt to find out.

Is this the 95 C4 ?

 

At light cruise, even 100% TCC duty only gives you
100% of bare minimum main line pressure on stock
LS1 tunes. Dunno about LT1 setups, but you ought
to have a look at the commanded line pressure or
force motor current. Smaller diameter converters
with a standard size clutch, need all the help they
can get.

That sort of road speed and TPS was where I had
all kind of slip trouble on my old converter. Barely
got it drivable with a bunch of tune fiddling but the
clutch was just too wimpy. Needed a lot more line
at light loads, to keep it locked.

Is this a new problem or been going on for a while
(like, since converter break-in)?

 

Yes, its the C4 converter used to lock. It quit I installed a transgo which should take the PWM out of the equation NO CHANGE.

Here's a shot prior to Shift kit

 

The converter is a couple of years old and it used to lock


I do shift a little higher than stock

It started with a slight vibration at around 80mph thats steadily gotten worse. However, I thought I had torque converter issues due to a shudder under moderate high speed acceleration. Then I datalogged and noticed that the slip rpm graph is all jagged when it used to be straight as an arrow at speed.

I have a noise when I shut the car off that I thought was one of the electric fans spinning down (rattling sound like the fan was spinning down with bad bearing) but after laying under car with it running and having my kid shut it off it was coming from under converter cover. I pulled the cover same noise. I pulled converter started car shut it down noise went away.




Mike

 

If it quit when you did the transgo you have miss assembled the ISO valve they give.

 

I bought the transgo kit prior to TCC not locking, it quit locking well before the install. I wasn't going to install the kit until I found the problem; but I was told that the transgo may fix it, so I installed it and no change.


Summary
(Noise and no lock prior to transgo) or transgo install made NO DIFFERENCE.

 

Help!

 

oK I miss understood
well that leaves TCC valve stuck , missing or damaged input shaft oring or converter I am afriad

 

I've seen the TCC apply valve wear out in these a lot too. Only fix is to replace the valve body. Have you tried to command it full on?

 

How do you command full on?

 

Is there an easy way to check for (or fix stuck TCC valve?) can input shaft O-ring be replaced during converter replacement?

.....or do I need a full tear down. Tranny works fine with the exception of lock up.

MIke

 

The TCC valve can be checked by removing the TCC solenoid the valves right above it,
The oring can and really should be replaced during converter replacement

 

I appreciate the help. OK so I pull the TCC solenoid, what do I do to ensure the the TCC valve is operational?

 

well you will see a little cove it partially covers the valvve. But you will see the valve. Take something like and ice pick and push up and stroke the valve up and down

But now I also had a guy the other nightwho installed a TG2 and used the ISO valve and had no lockup after it , In his case I had him reinstall his factory valve and modify it and he had lockup with pwm COMPLETELY ELIMINATED .