4+3 help needed
Thread Starter
Instructor
Joined: Feb 2000
Posts: 246
Likes: 2
From: Philadelphia Pa.
4+3 help needed
The overdrive in my 86' used to work until I changed the engine, now it will work on a down grade only. If I touch the gas at all it will shift out of overdrive. If I'm driving and using about ten percent throtle it won't even think about going in to over drive. I played around with the fluid, added, took out, and still no help. If anyone knows anything please pass it along.
Thanks,
Joe
Thanks,
Joe
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Now THAT is interesting. The O/D unit takes a total of 1.7 quarts of ATF. Did you flush the lines when you had the engine out? Does the light for overdrive come on and off on the dash, or does the O/D just do its own wierd thing?
Thread Starter
Instructor
Joined: Feb 2000
Posts: 246
Likes: 2
From: Philadelphia Pa.
Re: (scorp508)
The trans and overdrive unit were never taken out of the the car. So I just assumed it would still work. The gasket and fluid were changed about a thousand miles before the engine was replaced. And yes the light still works. It acts as if it used to take about thirty percent throtle to kick it out, like to pass someone on the highway, now takes about two percent.
Joe
Joe
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
What was done to your engine? Was your computer reprogrammed with a new chip? The 4+3 uses the torque convertor clutch tables and a few other fields for its logic about when to work, and when to do the auto disengagements. If you do not use the appropriate base file, you will royally mess up that tranny's brain. :)
Thread Starter
Instructor
Joined: Feb 2000
Posts: 246
Likes: 2
From: Philadelphia Pa.
Re: (scorp508)
The engine uses a DFI computer, The rest of the car uses the stock computer with the stock chip. This set up is good because you don't lose the dashboard. Any reprograming like deleat EGR , or AIR pump is handled by the DFI.
Joe
Joe
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Is the stock computer still receiving the signals from the following variables?
-Throttle Position Sensor
-Coolant Temperature (The ECM one, not the display one)
-1st Gear Switch on Transmission
-Vehicle Speed Sensor
-Tachometer Pulses
-Throttle Position Sensor
-Coolant Temperature (The ECM one, not the display one)
-1st Gear Switch on Transmission
-Vehicle Speed Sensor
-Tachometer Pulses
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
You're welcome. There is also a way to circumvent the ECM and make overdrive completely manual by cutting a wire or two and installing the 1985 on/off switch instead of the 86-88 momentary on switch in the shifter.
You could consider doing this, but personally I love having the auto-downshifts. :D
You could consider doing this, but personally I love having the auto-downshifts. :D
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Instructor
Joined: Jan 2002
Posts: 221
Likes: 0
From: League city Texas
Re: 4+3 help needed (jadedvette)
What about the throttle downshift cable. If it is not adjusted properly it could cause the problems you are indicating. Also check the connector for the relay. It is the one closest to the firewall near the brake booster it could be loose. While checking the connector also check the wires going into the connector to make sure the insulation hasn't deteriated.