shift problems
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Elder User
Joined: Oct 2004
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From: Fleming Ga
shift problems
Have a 90 ranger with an A4LD trans. Problem is quick upshifts and will not shift out of 4th when stopping until speed drops below 20 mph causing the truck to jerk and shake while coming to a stop. Originally had a problem with late upshifts due to a leaking modulator valve. Replaced the modulator and trans started shifting very quick on upshift. Adjusted the modulator ajdustment screw in 4 turns already trying to fix the shift problem. After each adjustment, the upshifts occur at higher MPH first time but once truck begins to warm up the upshifts drop back down and problem resumes. Truck sat for 1 year with a bad engine before I replaced the engine and trans problems started after engine replacement. Any suggestions what the problem is and what to do next? Wrong modulator, continue to adjust modulator, restriction in vacumn line???????
Thanks
Ron
Thanks
Ron
Junior User
Joined: Feb 2004
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your right check the vaccum line. take the modualter back and get a new one but dont adjust it there preset to the factory and about the truck shaking when you stop it could be that your Tourque Converter is locked up
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Elder User
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From: Fleming Ga
What makes the torque converter unlock? I thought that it was gear related and once it down shifted it should unlock. That's why I was concerned with shift points. With the trans quick shifting it may not be down shifting soon enough and staying in 3rd or 4th at too low an rpm. Is there any way to check to see if it is the torque converter is hanging up or not down shifting??
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the tc is not a gear realated the tc it self has a pressure plate in it that locks up the impeller and turbine inside the tc its controlled by hyrdrallic fluid and thats controlled by a soilnoid. the tc locks up at cruising speed. it locks up to reduce friction in the tranny so everything dont burn up.
when your crusing down the road at about 65 set it on cruise then after awhile tap the brakes lightly you should feel the tc unlock it should feel like a slight downshift the rpm should jump up about 100-300 rpm right after you tap the brakes and feel it start crusing again at 65 and the tc should lock up again you'll feel it
when your crusing down the road at about 65 set it on cruise then after awhile tap the brakes lightly you should feel the tc unlock it should feel like a slight downshift the rpm should jump up about 100-300 rpm right after you tap the brakes and feel it start crusing again at 65 and the tc should lock up again you'll feel it
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Elder User
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From: Fleming Ga
What controls the applying of the solenoid for lockup and overdrive. What is happening is the converter is locking and does not unlock until speed drops to 15mph. Another related problem is overdrive engages at 35 mph unless accelerating hard enough so that trans doesn't shift into 3rd until later then it is a 3rd/4th quick shift. If I drive the truck in drive (3rd gear) instead of OD everything works as it should with the exception on the converter not comoin out of lockup until 15 mph causing a shudder. Running in OD 4th gear seams to apply when it wants to, normally around 35 mph reguardless of acceleration and lockup doesn't release until 15 mph. I think the computer controls both lockup and overdrive but I don't know what inputs it uses to determing when to upshift/downshift and when to lockup/unlock. Does anyone know where to look????
Thanks
Ron
Thanks
Ron
