Converter unlocking, locking, unlocking
Thread Starter
TECH Enthusiast
Joined: Nov 2001
Posts: 688
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From: Derby, KS
Yeah, sorry, I should have posted this before, there are no current or pending DTC's nor have I had any before. I wish somebody would tell me exactly what to log and what, besides misfires, causes something like this. I'd like to keep it before I do something stupid like blow the thing up or trade it in on a new C6, which will ultimately leave me in divorce court. 
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
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From: So.Cal.
Yes, log these:
MAF
MAP
TP
RPM
VSS
GEAR
TFM PWM or TFM PRS
TFT
TCC PWM DC
TCC MODE
TCC apply state bit (it has different names depending on scantool)
TCC SLIP (take this with a grain of salt)
TCC Time
Misfire Total Counts
State bits that show the reasons why the PCM released the TCC
TCC MODE tells you when the PCM is commanding TCC locked.
MAF
MAP
TP
RPM
VSS
GEAR
TFM PWM or TFM PRS
TFT
TCC PWM DC
TCC MODE
TCC apply state bit (it has different names depending on scantool)
TCC SLIP (take this with a grain of salt)
TCC Time
Misfire Total Counts
State bits that show the reasons why the PCM released the TCC
TCC MODE tells you when the PCM is commanding TCC locked.
FormerVendor
Joined: Oct 2006
Posts: 3,123
Likes: 3
From: D-F/W
Hey guys sorry for the lapse here....
Just got off the phone with the OP after a long discussion about these symptoms with John here at the shop.
While the symptoms could be related to an electrical issue, our opinion is that there is a pressure loss / leak at very low throttle. The indicator here is the fact that the tranny does not engage Low at stops intermittantly, and in addition this could explain the poor converter engagement.
Both the Lock Up function and 1st gear engagement happen at very low throttle inputs. Keeping that in mind we suggested a worn or sticking pressure relief valve as an example of why this occurs.
We recommended that a pressure guage be installed and the car be driven to see just what the pressure is at low throttle inputs.
Stay in touch Dave, it was nice talking to you.
g
Just got off the phone with the OP after a long discussion about these symptoms with John here at the shop.
While the symptoms could be related to an electrical issue, our opinion is that there is a pressure loss / leak at very low throttle. The indicator here is the fact that the tranny does not engage Low at stops intermittantly, and in addition this could explain the poor converter engagement.
Both the Lock Up function and 1st gear engagement happen at very low throttle inputs. Keeping that in mind we suggested a worn or sticking pressure relief valve as an example of why this occurs.
We recommended that a pressure guage be installed and the car be driven to see just what the pressure is at low throttle inputs.
Stay in touch Dave, it was nice talking to you.
g
FormerVendor
Joined: Oct 2006
Posts: 3,123
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From: D-F/W
Originally Posted by Ragtop 99
FWIW, I'll disagree with Gilberts's advice on locking. locking in third gear should not be an issue and ther's no reason why you can't lock at speeds lower than 55 mph. It makes driving a high stall much more tolerable. I would lock in third and raised my 3-4 upshift to keep the car from being a dog in town.
Please consider my recommendations to only be a baseline for which one can base further driveability tuning decisions for the given combination. Not a true driveability straqtegy.
g
Thread Starter
TECH Enthusiast
Joined: Nov 2001
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From: Derby, KS
Ding ding ding...we have a winner! Gilbert nailed it, low line pressure. Had a broken pressure regulator spring and another broken spring (?) in the valve body. Not sure about the valve body part that broke but I think he said it was a spring. Anyway, got the trans completely rebuilt and the stock converter reinstalled (in preparation for selling the car in a year or two) My tranny guy said he thinks the Yank is probably fine, he did not find any clutch material in the trans. I'll probably sell the Yank.
Last edited by Dave Carney; Aug 1, 2007 at 07:51 PM.
Glad to hear it was solved.
That SY 3500 is gold if it Yank will throw a new clutch in it. Lots of guys looking for a converter for the street that won't blow the tires away at 25% throttle.
Bet it will be wierd to drive stock again. You could cheat a bit and have them restall the stocker to about 2400 rpm for not much money.
That SY 3500 is gold if it Yank will throw a new clutch in it. Lots of guys looking for a converter for the street that won't blow the tires away at 25% throttle.
Bet it will be wierd to drive stock again. You could cheat a bit and have them restall the stocker to about 2400 rpm for not much money.
FormerVendor
Joined: Oct 2006
Posts: 3,123
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From: D-F/W
Originally Posted by Ragtop 99
Glad to hear it was solved.
Bet it will be wierd to drive stock again. You could cheat a bit and have them restall the stocker to about 2400 rpm for not much money.
Bet it will be wierd to drive stock again. You could cheat a bit and have them restall the stocker to about 2400 rpm for not much money.
Thats actaully good advice. We recommend that factory converters be "maxed out" when the car has bolt ons with no immediate plans for significant H/P upgrades. It provides for good driveability and decent mileage as well.
But it is not good for the guy who is chasing 60' times!
The converter shop we use does the converter for about $125.00.
g
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TECH Enthusiast
Joined: Nov 2001
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From: Derby, KS
Well, nuts....something bad just happened at 40 miles since rebuild...tried to pull away from a stop, had very low power, car did not want to go, check engine light came on, trans acted weird, and it feels like 4th is gone, I crippled it back over to the tranny shop. It felt to me like the line pressure was too high and I had called him this morning before it blew to let him know. He thought though, having driven it himself, that it was normal for the stock converter with this trans. Dunno....we'll see I guess. 
Sounds like you set limp mode , Its likley and electrical issue. Let us know what codes in there?
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Thread Starter
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From: Derby, KS
Ok, I'm back in the saddle again. A shift solenoid (that was new as part of the rebuild) died, leaving me with just second and third gear I think. Why did it die? Dunno, Ken thought it was just a dud. Anyway, he replaced it and that's all the tranny needed.
Then we chatted about the seemingly high line pressure. He offered to convert me back to a force motor for no charge if I wanted but he noticed that the idle seemed high, 1100 on the tach in park and 1000 in drive. I had turned it down from 800 to 700 using Edit but that's not what it was doing, it (the idle air control) was unable to adjust down that far. So, got it home and started searching for a vacuum leak and found it at the pcv to throttle body connection. So, I got the idle down, got the vacuum up, and presto, no more head jolting when moving the selector from R to OD.
Now hopefully I'm done. (gulp) What kills a shift solenoid other than manufacturing defect?
A shift solenoid (that was new as part of the rebuild) died, leaving me with just second and third gear I think. Why did it die? Dunno, Ken thought it was just a dud. Anyway, he replaced it and that's all the tranny needed. Then we chatted about the seemingly high line pressure. He offered to convert me back to a force motor for no charge if I wanted but he noticed that the idle seemed high, 1100 on the tach in park and 1000 in drive. I had turned it down from 800 to 700 using Edit but that's not what it was doing, it (the idle air control) was unable to adjust down that far. So, got it home and started searching for a vacuum leak and found it at the pcv to throttle body connection. So, I got the idle down, got the vacuum up, and presto, no more head jolting when moving the selector from R to OD.
Now hopefully I'm done. (gulp) What kills a shift solenoid other than manufacturing defect?
FormerVendor
Joined: Oct 2006
Posts: 3,123
Likes: 3
From: D-F/W
Dave that's good news indeed! I know you have been struggling with that car for a while now.
As far as the solenoid... that's the racing gods poking fun at you, your turn in the barrel!
Good Luck. Enjoy the car finally.
g
As far as the solenoid... that's the racing gods poking fun at you, your turn in the barrel!
Good Luck. Enjoy the car finally.
g
