need help with TCC setup
08-08-2002, 07:11 PM
#1
Member
Thread Starter
Join Date: Feb 2001
Location: Lenhartsville, PA
Posts: 464
Likes: 0
Received 0 Likes
on
0 Posts
need help with TCC setup
I've been trying to solve this problem for about a week now and it started when I tried to invoke highway mode. I've done tons of searches and a lot of reading and I can't figure it out so I have to ask.
The problem is as soon as my TCC engages it disengages and feels like it's almost chattering. I have a 3 month old pro-built tranny and TC, and a brand new 4-pulse VSS which I installed today (thought that might be the problem). I'm positive it's not the equipment and it's just something I'm missing in the prom.
I've played with everything and it just makes it worse or not work at all. I even set everything back to the way it was in the stock AUJP bin. Now it only locks up in fourth and I have to stay on the gas hard for it to stay locked up. In third it doesn't do anything. Every once in a while it will lock up quick and then disengage.
Any advice would be appreciated.
The problem is as soon as my TCC engages it disengages and feels like it's almost chattering. I have a 3 month old pro-built tranny and TC, and a brand new 4-pulse VSS which I installed today (thought that might be the problem). I'm positive it's not the equipment and it's just something I'm missing in the prom.
I've played with everything and it just makes it worse or not work at all. I even set everything back to the way it was in the stock AUJP bin. Now it only locks up in fourth and I have to stay on the gas hard for it to stay locked up. In third it doesn't do anything. Every once in a while it will lock up quick and then disengage.
Any advice would be appreciated.
08-09-2002, 07:05 AM
#2
Moderator
iTrader: (1)
Join Date: Mar 2002
Location: Chasing Electrons
Posts: 18,405
Likes: 0
Received 216 Likes
on
202 Posts
Car: check
Engine: check
Transmission: check
It sounds as though the two TPS% vs MPH unlock/relock tables are
reversed. These tables are paired and provide two different TPS%
requirements dependent upon whether the TCC is currently locked
or unlocked.
1) If the TCC is locked the table used will be the TPS% to exceed to
unlock the TCC.
2) If the TCC is unlocked the table used will be the TPS% to be less then
to re-lock the TCC.
The 'is locked' table (#1) will have the larger TPS% values.
RBob.
reversed. These tables are paired and provide two different TPS%
requirements dependent upon whether the TCC is currently locked
or unlocked.
1) If the TCC is locked the table used will be the TPS% to exceed to
unlock the TCC.
2) If the TCC is unlocked the table used will be the TPS% to be less then
to re-lock the TCC.
The 'is locked' table (#1) will have the larger TPS% values.
RBob.
08-09-2002, 11:03 AM
#3
Member
Thread Starter
Join Date: Feb 2001
Location: Lenhartsville, PA
Posts: 464
Likes: 0
Received 0 Likes
on
0 Posts
(not in fourth)
TCC lock TCC unlock
mph %tps mph %tps
44 46.9 44 32.0
Here is an example of my table at 44 mph. So what you are saying is that at 44 mph the TCC will stay locked until my tps exceeds 46.9%, and it will stay unlocked until my tps goes below 32.0%.
If that is the case my table shoud be setup right and it still doesn't work properly.
Thanks for the help. I guess it must be mechanical because everything else with the TCC is just flags and constants and I know I have that part right.
BTW: Is there a minimum %tps for the TCC to engage? When I had it working right it would unlock every time I let off the gas and lock back up as soon as I got back on it. It got kind of annoying.
TCC lock TCC unlock
mph %tps mph %tps
44 46.9 44 32.0
Here is an example of my table at 44 mph. So what you are saying is that at 44 mph the TCC will stay locked until my tps exceeds 46.9%, and it will stay unlocked until my tps goes below 32.0%.
If that is the case my table shoud be setup right and it still doesn't work properly.
Thanks for the help. I guess it must be mechanical because everything else with the TCC is just flags and constants and I know I have that part right.
BTW: Is there a minimum %tps for the TCC to engage? When I had it working right it would unlock every time I let off the gas and lock back up as soon as I got back on it. It got kind of annoying.
08-09-2002, 11:32 AM
#4
Moderator
iTrader: (1)
Join Date: Mar 2002
Location: Chasing Electrons
Posts: 18,405
Likes: 0
Received 216 Likes
on
202 Posts
Car: check
Engine: check
Transmission: check
Originally posted by IROCZ88
(not in fourth)
TCC lock TCC unlock
mph %tps mph %tps
44 46.9 44 32.0
Here is an example of my table at 44 mph. So what you are saying is that at 44 mph the TCC will stay locked until my tps exceeds 46.9%, and it will stay unlocked until my tps goes below 32.0%.
(not in fourth)
TCC lock TCC unlock
mph %tps mph %tps
44 46.9 44 32.0
Here is an example of my table at 44 mph. So what you are saying is that at 44 mph the TCC will stay locked until my tps exceeds 46.9%, and it will stay unlocked until my tps goes below 32.0%.
BTW: Is there a minimum %tps for the TCC to engage? When I had it working right it would unlock every time I let off the gas and lock back up as soon as I got back on it. It got kind of annoying.
the threshold the TCC will unlock.
From the ANHT hac:
Code:
L8315: FCB 32 ; COAST RELEASE, TPS SW POINT, (32 MPH) ; L8316: FCB 8 ; LO NPH COAST LOAD LIMIT, 3% TPS L8317: FCB 0 ; HI NPH COAST LOAD LIMIT, 3% TPS ; L8318: FCB 3 ; TPS HYST FOR coast release
threshold at L8315. Then the hysteresis used at L8318 before
a relock.
RBob.
08-09-2002, 12:10 PM
#5
Member
Thread Starter
Join Date: Feb 2001
Location: Lenhartsville, PA
Posts: 464
Likes: 0
Received 0 Likes
on
0 Posts
Thanks, I'll have to mess around with that.
BTW: I found the problem. Today as I was driving home from work my check engine light came on, so I burned a chip with vehicle speed diagnostics turned off. I went for a drive and the light didn't come on again. This led me to believe that I had a problem with the VSS, so I checked it out and it looked fine.
Then I pulled the speedo gear housing out of the tailshaft housing and the driven gear is completely stripped. I guess I have to get new speedo gears.
BTW: I found the problem. Today as I was driving home from work my check engine light came on, so I burned a chip with vehicle speed diagnostics turned off. I went for a drive and the light didn't come on again. This led me to believe that I had a problem with the VSS, so I checked it out and it looked fine.
Then I pulled the speedo gear housing out of the tailshaft housing and the driven gear is completely stripped. I guess I have to get new speedo gears.
08-09-2002, 03:16 PM
#6
Moderator
iTrader: (1)
Join Date: Mar 2002
Location: Chasing Electrons
Posts: 18,405
Likes: 0
Received 216 Likes
on
202 Posts
Car: check
Engine: check
Transmission: check
Thanks for the update. Wow, first time ever I've heard
of the speedo gear breaking up. It most certainly will
cause problems though <g>.
RBob.
of the speedo gear breaking up. It most certainly will
cause problems though <g>.
RBob.
08-09-2002, 10:14 PM
#7
Supreme Member
Join Date: Jun 2002
Location: great lakes
Posts: 1,787
Likes: 0
Received 0 Likes
on
0 Posts
ahh speedo gear destruction is quite normal in the 700r4,4l60.4l60e. after a couple of years of use the gear just get brittle. replace the worm and the output shaft gear. BTW this is standard in any good rebuild.
Trending Topics
08-09-2002, 10:40 PM
#8
Junior Member
Join Date: Jan 2002
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
slight change in code topic
RBob-
Thanks for posting that. It's the most concise explanation of TCC Lock-Up that I've seen, and the best. Since you seem to have a gift for the code, may I pose a similar question (and change topics a little)?
About a third of the way through the ANHT hack there is a section on computing dynamic spark dwell. As I read it, it seems to have a minimum value of 3.5 ms, and a max time of 'DRP period/8'.
Is that reading correct? In between it seemed to handle transients by averaging 2 DRP's (?); then it does something to add either 4.7 or 5.8 ms, but i'm not sure to what - it looks like it adds when the dwell is less than 3.5 ms. Does that make the max dwell 3.5+5.8=9.3 at short DRP times? It's confusing to sort through.
BTW (since I've already imposed on your good nature), from a literature search I'm under the impression that the GM 7-pin ignition module is current limited to something like 7 amps. Is that your recollection?
Many thanks for your help
BTW2 - FWIW, I've run the same 700R4 for the last 10+ years and haven't seen a problem with the nylon VSS gears. Some people may not be aware that there are various VSS housings with different shaft offsets (to accommodate different diameter driven gears). I imagine if you used the wrong housing, you could still bolt it up & force the plastic gears to mesh, but they wouldn't last very long.
Thanks for posting that. It's the most concise explanation of TCC Lock-Up that I've seen, and the best. Since you seem to have a gift for the code, may I pose a similar question (and change topics a little)?
About a third of the way through the ANHT hack there is a section on computing dynamic spark dwell. As I read it, it seems to have a minimum value of 3.5 ms, and a max time of 'DRP period/8'.
Is that reading correct? In between it seemed to handle transients by averaging 2 DRP's (?); then it does something to add either 4.7 or 5.8 ms, but i'm not sure to what - it looks like it adds when the dwell is less than 3.5 ms. Does that make the max dwell 3.5+5.8=9.3 at short DRP times? It's confusing to sort through.
BTW (since I've already imposed on your good nature), from a literature search I'm under the impression that the GM 7-pin ignition module is current limited to something like 7 amps. Is that your recollection?
Many thanks for your help
BTW2 - FWIW, I've run the same 700R4 for the last 10+ years and haven't seen a problem with the nylon VSS gears. Some people may not be aware that there are various VSS housings with different shaft offsets (to accommodate different diameter driven gears). I imagine if you used the wrong housing, you could still bolt it up & force the plastic gears to mesh, but they wouldn't last very long.
Last edited by Kaiser; 08-09-2002 at 11:08 PM.
08-11-2002, 05:02 AM
#9
Moderator
iTrader: (1)
Join Date: Mar 2002
Location: Chasing Electrons
Posts: 18,405
Likes: 0
Received 216 Likes
on
202 Posts
Car: check
Engine: check
Transmission: check
I really do not have a hard number for the current limiting of
the coil.
As for the dynamic dwell calc it is a bit complicated. Dynamic
dwell is only used during periods of acceleration. It is first
qualified by a rising MAP value. Another routine decays this
additional (dynamic) dwell out (mis-labeled as 'calc dynamic dwell'
in the ANHT hac).
If the engine speed continues to increase (delta DRP) the dynamic
dwell also continues to be added.
The minimum dynamic dwell is: 2 * (OldRefPeriod - NewRefPeriod)
The maximum dynamic dwell is as you mentioned: NewRefPeriod / 8
In total there are three dwell values that are added together for
the final dwell: dynamic, static, vehicle voltage compensation.
This final value is then limited to ensure a 600usec firing time.
The static dwell is a three slope line. It is dependent upon the
engine speed (RefPeriod).
The vehicle voltage compensation adds 610usec of dwell for each
volt below 12.0 volts. This is done with a 0.1 volt granularity.
The detection of increased engine load will vary depending upon
the ECM MaskId in use. For example the $8D and $42 ('747) use a
rising MAP value. The $58 uses AE as the qualifier.
RBob.
(For those that are lost this post has to do with the charging
of the ignition coil. GM ECMs are very much atune to ignition
events as they are fueling events. The calculated dwell ensures
that enough energy is imparted to the spark plugs to fire the
mixture under the various load conditions).
the coil.
As for the dynamic dwell calc it is a bit complicated. Dynamic
dwell is only used during periods of acceleration. It is first
qualified by a rising MAP value. Another routine decays this
additional (dynamic) dwell out (mis-labeled as 'calc dynamic dwell'
in the ANHT hac).
If the engine speed continues to increase (delta DRP) the dynamic
dwell also continues to be added.
The minimum dynamic dwell is: 2 * (OldRefPeriod - NewRefPeriod)
The maximum dynamic dwell is as you mentioned: NewRefPeriod / 8
In total there are three dwell values that are added together for
the final dwell: dynamic, static, vehicle voltage compensation.
This final value is then limited to ensure a 600usec firing time.
The static dwell is a three slope line. It is dependent upon the
engine speed (RefPeriod).
The vehicle voltage compensation adds 610usec of dwell for each
volt below 12.0 volts. This is done with a 0.1 volt granularity.
The detection of increased engine load will vary depending upon
the ECM MaskId in use. For example the $8D and $42 ('747) use a
rising MAP value. The $58 uses AE as the qualifier.
RBob.
(For those that are lost this post has to do with the charging
of the ignition coil. GM ECMs are very much atune to ignition
events as they are fueling events. The calculated dwell ensures
that enough energy is imparted to the spark plugs to fire the
mixture under the various load conditions).
08-12-2002, 09:56 PM
#10
Junior Member
Join Date: Jan 2002
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
Dwell calc
RBob
Thank you very much for your insight.
I have to go back and read the hack more - I thought that was the entire dwell calc, but I seem to have missed the static part entirely.
I'm just trying to understand what the spark is doing, so I can make some sort of informed decision on whether I need a new coil. Thanks again.
k
Thank you very much for your insight.
I have to go back and read the hack more - I thought that was the entire dwell calc, but I seem to have missed the static part entirely.
I'm just trying to understand what the spark is doing, so I can make some sort of informed decision on whether I need a new coil. Thanks again.
k
Thread
Thread Starter
Forum
Replies
Last Post
LT1Formula
Engine/Drivetrain/Suspension Parts for Sale
7
10-08-2015 08:34 PM