tcc shifting to early in 1st stage.
02-13-2006 | 09:15 AM
#1
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Joined: Nov 2003
Posts: 18
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From: kentucky
Car: 86 irocz
Engine: 305ho
Transmission: 700r4
tcc shifting to early in 1st stage.
86 305 iroc 700r4
The car shifts fine while cold or under moderate to heavy accelerations. Once car is up to temp it will lock up tork convertor in over drive at low rpms. For example I come to a stop sign and stop when I take off under normal acceleration this is when it occurs. You can feel the car down shift to first correctly and it gos thru 1,2,3 then lock up and it will hit 4th around 42 mph correctly. To over come this I have to accelerate med to heavy. Tps is cal. correct. I have the gm shop manual but cannot seem to fine a good direction to go to next. Where should I start trouble shooting next? Thanks: 49m
The car shifts fine while cold or under moderate to heavy accelerations. Once car is up to temp it will lock up tork convertor in over drive at low rpms. For example I come to a stop sign and stop when I take off under normal acceleration this is when it occurs. You can feel the car down shift to first correctly and it gos thru 1,2,3 then lock up and it will hit 4th around 42 mph correctly. To over come this I have to accelerate med to heavy. Tps is cal. correct. I have the gm shop manual but cannot seem to fine a good direction to go to next. Where should I start trouble shooting next? Thanks: 49m
02-13-2006 | 10:25 AM
#4
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From: Calgary, AB
Car: 1993 Nissan 240sx
Engine: Turbo KA24DE
Transmission: 5 spd
Axle/Gears: 4.08 VLSD
I also think the way you described it sounds right. Or do you mean to say that it locks up at way under 42 mph when warm? Because otherwise, lugging the motor down is pretty much a side effect of fuel economy.
02-13-2006 | 10:29 AM
#5
Joined: Sep 2005
Posts: 26,587
Likes: 1,901
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
No, I understand perfectly.
That's what it's supposed to do.
Now whether you think it could do something else and it would be better, or you just don't like it and wish it would do something else, that's a different matter.
But it sounds like it's doing exactly what GM thought it should do and made it to do.
That's what it's supposed to do.
Now whether you think it could do something else and it would be better, or you just don't like it and wish it would do something else, that's a different matter.
But it sounds like it's doing exactly what GM thought it should do and made it to do.
02-13-2006 | 10:31 AM
#6
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Junior Member
Joined: Nov 2003
Posts: 18
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From: kentucky
Car: 86 irocz
Engine: 305ho
Transmission: 700r4
Funny thing I have Two off these cars and a 92 chevy truck with the same trans and they dont do it. Also this one did not do this when I first got the car.
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02-13-2006 | 12:23 PM
#9
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iTrader: (1)
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From: Calgary, AB
Car: 1993 Nissan 240sx
Engine: Turbo KA24DE
Transmission: 5 spd
Axle/Gears: 4.08 VLSD
Ok, then now that we have that sorted out, the question is why is it locking up at really low spd when warm?
Well, what engine is it? lb9? That would mean it has a computer and is therefore nothing like my '86 trans am non cc lg4, but I would say you should check the vacuum hoses going to the vacuum lockup switch (uh, if you have one) and then the next question is have you done anything to the computer?
Well, what engine is it? lb9? That would mean it has a computer and is therefore nothing like my '86 trans am non cc lg4, but I would say you should check the vacuum hoses going to the vacuum lockup switch (uh, if you have one) and then the next question is have you done anything to the computer?
02-13-2006 | 02:10 PM
#11
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Joined: Apr 2002
Posts: 1,353
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From: Austin
Car: 82 Z-28
Engine: 383 TPI
Transmission: 700R4
Mine did that after I swapped the TPI/700r4 eng/tranny into my 82. There are speed limits on the prom for the min speed the converter can lock up. There's seperate settings for 3 gear and 4th gear. I set mine to 255 mph for 3rd gear and abt 45 mph for OD. This prevents the converter from ever locking in 3rd gear and the 45 mph for OD keeps the converter from locking at too low a speed and lugging the eng. I also did it to prevent the tranny from shifting from 3rd to OD while the converter was locked which I didn't like.
I think there is also a min coolant temp for torque conv lock-up. Can't remember for sure. It's been a while since I messed with that stuff.
I imagine you were looking for an easier fix, but this is the only way I know to address it without going to a toggle switch for the converter.
I think there is also a min coolant temp for torque conv lock-up. Can't remember for sure. It's been a while since I messed with that stuff.
I imagine you were looking for an easier fix, but this is the only way I know to address it without going to a toggle switch for the converter.
02-13-2006 | 04:26 PM
#12
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Junior Member
Joined: Nov 2003
Posts: 18
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From: kentucky
Car: 86 irocz
Engine: 305ho
Transmission: 700r4
thanks that is a option. Does anyone have the information on what inputs of the ecm effect the tcc controls. Such as tps and temp switchs ect.
02-13-2006 | 08:24 PM
#13
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The Emperor of the Ottoman, King of the Couch, Duke of the Davenport is correct. He just didn't elaborate.
The stock programming for an '86 LB9 with TH700-R4 will lock the converter as low as 13MPH under some conditions. There is/was a TSB regarding this, some other issues, and the proper repair for the "problem". The 1986 model year is the ONLY one with this problem.
The only sensor that affects this is the VSS for vehicle speed. The ECM does the rest by calculating engine load and shifting the TCC accordingly. The only real "fix" for this is to replace the defective programming. The factory upgrade calibration is better, but custom programming is far better yet.
The stock programming for an '86 LB9 with TH700-R4 will lock the converter as low as 13MPH under some conditions. There is/was a TSB regarding this, some other issues, and the proper repair for the "problem". The 1986 model year is the ONLY one with this problem.
Code:
PONTIAC ROUGH IDLE, CHUGGLE, LOW SPEED. Page: 1
86-6(GAS)-66 Issued: 10/17/86
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1986 FIREBIRD VEHICLES WITH 5.0L LB9
TPI ENGINE (ENGINE CODE F)
New service calibrators (Ref: Called Mem-Cal In Shop Manual) have been
released for the 1986 Firebirds with the 5.OL TPI engine. These new
calibrators will address the following customer comments:
1. "Rough Idle" on both hot and cold engine - the idle speed is raised to 650
plus or minus 50 RPM.
2. "Chuggle or Shudder" at low speeds - torque converter clutch (TCC)
engagement speed is raised to 41 MPH.
3. "Hesitation" on light acceleration with a hot engine.
4. "Cold Driveability" - New calibration eliminates light to moderate sag on
cold driveaway.
5. "Service Engine Soon” Lights - Eliminates the following false Codes:
A. Code 32 - EGR System failure
B. Code 33 - Mass Airflow Sensor Voltage High
C. Code 34 - Mass Airflow Sensor Voltage Low
D. Code 43 - Electronic Spark Control
E. Code 44 - Lean Exhaust Indication
If normal engine diagnostics and repair do not correct the above conditions,
it will be necessary to replace the calibrator in the ECM. Below is a listing
of the new calibrators and their usages.
ON AIR CONDITIONING (C-6O) FIREBIRDS
With QYZ (P215/65 R 15/N 15" Tire) Use - 1228290 Calibrator
With QAC (P235/60 VR 15N Tire) Use - 1228291 Calibrator
With QDZ (P245/50 VR 16N Tire) Use - 1228291 Calibrator
ON NON-AIR CONDITIONING (C-41) FIREBIRDS
With QYZ (P215/65 R 15/N 15" Tire) Use - 1228292 Calibrator
With QAC (P235/60 VR 15N Tire) Use - 1228293 Calibrator
With QDZ (P245/50 VR 16N Tire) Use - 1228293 Calibrator
Use Applicable Labor Time and Operation Numbers.
1228291 Calibrator available $63.64 F.O.B. factory 
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