North American Turbocoupe Organization



A4LD Erratic Shifts
Kirk600 Offline
Junior Member
#1
Greetings,
 My 1987 turbo coupe suddenly started shifting late, like around 4500rpm in normal town driving. No issues at all prior, car has 115,000 miles...I thought, aha must be vacuum so I replaced the vacuum modulator and fluid and filter. Still exactly the same. The new modulator is adjustable so I turned the screw out probably 6-8 turns and no change. I tested the new and old one with my mity vac and they both hold vacuum and the diaphragm moves. I did remember to reinstall the pin into the new one.
 I tried to remove the main engine vacuum line from the intake From the tree, and hook that up to the vacuum line for the transmission ( basically eliminates vacuum to everything else) and still no change. My motor makes 17-18 inches of vacuum at idle. 

Anyone have any ideas? Tried disconnecting the kickdown cable and still no change. The car will shift 1/2 manually as soon as you move the shifter, 2/3 is delayed and usually requires you to let off the accelerator, or shift to OD, or be traveling over 45mph
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88turbomajor Offline
Member
#2
(10-26-2022, 12:13 AM)Kirk600 Wrote: Greetings,
 My 1987 turbo coupe suddenly started shifting late, like around 4500rpm in normal town driving. No issues at all prior, car has 115,000 miles...I thought, aha must be vacuum so I replaced the vacuum modulator and fluid and filter. Still exactly the same. The new modulator is adjustable so I turned the screw out probably 6-8 turns and no change. I tested the new and old one with my mity vac and they both hold vacuum and the diaphragm moves. I did remember to reinstall the pin into the new one.
 I tried to remove the main engine vacuum line from the intake From the tree, and hook that up to the vacuum line for the transmission ( basically eliminates vacuum to everything else) and still no change. My motor makes 17-18 inches of vacuum at idle. 

Anyone have any ideas? Tried disconnecting the kickdown cable and still no change. The car will shift 1/2 manually as soon as you move the shifter, 2/3 is delayed and usually requires you to let off the accelerator, or shift to OD, or be traveling over 45mph

https://picclick.com/%E2%80%9885-%E2%80%...51833.html

Shift solenoid?
1984 Mercury Cougar 5.0L LS Silver/Gray (New 5.0L with E7 heads and HO cam)
Previous: 1988 Turbo Coupe
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Kirk600 Offline
Junior Member
#3
Thanks turbomajor, but it is my understanding that this is for the 3/4 shift and another one is for the converter lockup.... my cars issues happen at every up shift. My car also has a more pronounced engagement when putting it in gear, from park or neutral.
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Mikey97D Offline
Member
#4
(10-28-2022, 01:08 AM)Kirk600 Wrote: Thanks turbomajor, but it is my understanding that this is for the 3/4 shift and another one is for the converter lockup.... my cars issues happen at every up shift. My car also has a more pronounced engagement when putting it in gear, from park or neutral.

I used to see that on older cars if the vacuum line was pinched or broken.   Does the A4LD have a vacuum line going to it?  And if so does it have a check valve for when under boost?
1988 TC, 5 spd, Stinger 3" Exhaust, Schneider Roller Cam, -4° Cam Pulley, Cone Filter, Gilles Boost Control Valve set at 17 psi, Walbro 255 lph, CHE Rear Lower and Upper Control Arms, Braided Brake Lines, Hawk HPS 5.0 Front and HPS (F) Rear, CRES Inserts in front calipers, and '93 Cobra Wheels with General 235/50R17 Tires.   
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Kirk600 Offline
Junior Member
#5
Yes It has a vacuum line that goes to the vacuum modulator on the side of the transmission. I replaced the modulator, and was sure to replace the pin inside. I also tried testing the metal vacuum line with my mityvac and it holds vacuum.
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Kirk600 Offline
Junior Member
#6
I will have to check for a check valve, for that specific line.
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Kirk600 Offline
Junior Member
#7
Well as I suspected, but was troubleshooting all options first, internal damage to the transmission and it is getting a full rebuild
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88turbomajor Offline
Member
#8
(11-21-2022, 02:30 PM)Kirk600 Wrote: Well as I suspected, but was troubleshooting all options first, internal damage to the transmission and it is getting a full rebuild

Dang,  Sorry to hear that... Hope it all goes well.
1984 Mercury Cougar 5.0L LS Silver/Gray (New 5.0L with E7 heads and HO cam)
Previous: 1988 Turbo Coupe
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Kirk600 Offline
Junior Member
#9
I am still waiting for my car to be done.... lots of trouble getting some of the parts
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