Ralls

iTrader: (32)

For some reason my converter just won't lock up when I go into overdrive (45mph). I drove the car this morning and noticed it locked up normally. Then when I drove the car again less than an hour later, it wouldn't lock up. My car has been fine for nearly a year with this converter.

My cruise control still works, so the brake switch isn't stuck on.

I'm not throwing any codes at all. I have "Tuner Cats" and "Free Scan" to monitor and change the PCM tables if I need to. My software doesn't show TCC, so I'm not sure if it's engaging. But I figured it would throw a code if the TCC has malfunctioned.

I've done a search and noticed some talk about a small missfire, but I don't have a missfire to my knowledge. Anyone have a clue?

LS1 Sounds

iTrader: (11)

Sounds like a misfire condition. Does your software have controls that allow you to command a TC lockup while driving? If it locks/unlocks correctly via this control then the TC is fine and you need to find out what is wrong in the tune.

PS, this happens a lot with cammed LS1s.

Ralls

iTrader: (32)

My software doesn't let me lock/unlock the TC on the fly. I looked at the TCC tables and they all still say to lockup at 44mph.. so nothing got messed up with that. I have my Stock tune and the Dyno tune saved in my software. I went back to the stock tune but the TC still doesn't lock.

I went to the track today and my times did not show any indication of a misfire. It runs perfect. When this misfire condition happens to some cammed LS1's, does it show any code? Because I'm getting no feedback about a missifre.

LS1 Sounds

iTrader: (11)

The software controls (if you had them available) would bypass any misfire codes and attempt to lock the converter. Not sure on an LT1, but an LS1 tune settings will not lock the TC if the computer detects misfire.

On a cammed LS1, code P0300 is pretty reliably set. After you disable it, getting additional codes is hit or miss. Some cars throw a code, some flash the SES light; my '98 shows absolutely nothing except for the converter won't lock consistently. Otherwise, the cars I have tuned continue running correctly just with an unlocked TC.

Ralls

iTrader: (32)

Ok well since your 98 doesn't show a code like mine, what did you do? Were you actually getting a misfire or did the PCM just think it did? Because I'm telling you, I don't feel a misfire at all.

performabuilt

iTrader: (25)

I would tend to think it would have to be a tuning issue/missfie and not likley a mechanical issue with the trans or converter since even in 94 if the PCM comands lockup and it does not occur the PCM will iluminate the ses and set code PO1870 now one thing you may check is the coolant temp sensor if it does not show the engine over aprox 140 f the converter will be disallowed from locking.

Ralls

iTrader: (32)

I was doing some data logging before and didn't notice any abnormal CTS voltage readings. My car does go to open loop, so it should be showing over 140*F. But I'll check again once it stops pouring.

LS1 Sounds

iTrader: (11)

I could not feel anything amiss either, and my TCC would lock properly about 50% of the time. There are some misfire.cfg files available on the HP Tuners message forums that will help diagnose. The tables you want are under the Engine Diagnostics > Misfire tab, again in HPT.

Ralls

iTrader: (32)

You know what, I was going to mention my car seemed to lock up once. I thought it was all in my head. I was driving in the 45mph range and one time when it dropped in 3rd and I sped up for 4th, I felt it lock. I ended up giving it gas and it down shifted and never went back to lock.

I'm going to check the CTS right now.

Ralls

iTrader: (32)

My CTS is fine. It was running at 180*F @ 3.2volts (I have a thermostat). I couldn't see anything abnormal. Although my software can't see much anyhow. I'm trying to get a hold of a better scan tool like a Modis or Master Tech. I would attach the data log but I don't know to attach files.

Ralls

iTrader: (32)

I found out my software can disable:
-TCC enable/disable
-TCC release at low TPS
-TCC release with rapid TPS
-Downshift Turns TCC off
(All are enabled)

Anything I should toy with?
It seems my converter locks when I let off the gas. It engine brakes and I also feel it disable when I hit the brakes. I'm guessing it instantly unlocks when I give it gas.

I just noticed something. I said my CTS was 180*F at 3.2v according to my software. I looked at a GM diagram and it says at 3.2v, it's at about 140*F. So something must be messed up since performabuilt said it won't lock under 140*F.

the_merv

iTrader: (88)

PVM Solenoid could be goin out..

Ralls

iTrader: (32)

You mean PWM (Pulse Width Modulation)?