When im driving more then 15-20mph i can hear a grinding like a fishing pole being pulled out. could this be a bad torque converter "free spooling" or something? my trucks slips a lot as well and when im coming to a stop i hear a loud downshift like noise.

 

Welcome to FTE and the Big Bronco Forum. Help us help you a bit better. What year is your Bronco? If you know which transmission is in it that would be helpful too though its not critical. Have any modifications been made to it? (suspension lift, larger tires, axle swap, etc.)

The noises you are hearing could originate from many sources including the differential (front and/or rear), transfer case, driveshaft(s).

When you say "my truck slips a lot" do you mean it feels like the transmission is slipping or that it loses traction easily?

Sorry for all the added questions, just hoping to give better insight. Given what we know right now, there could be any number of potential causes for the noises you are hearing.

 

Whoops sorry, I have a 93 Bronco 351w, 6 inch lift on 35's, Stock axles (d44 and 8.8) I ran some trouble codes and got these, 126, 327, 334, 624, and 628. here is the website to check the codes 1983 Ford Bronco Diagrams picture | SuperMotors.net . I have no idea what it could be. when i am doing about 45 mph and i let off the gas, my truck shudders for a few seconds almost like a rumble strip and then stops.

 

Ok, so we are dealing with an E4OD electronic automatic. Codes 624 and 628 are "transmission related".

624 - Solenoid circuit failure
628 - Excessive converter slippage

Neither is very nice and one may well be causing the other. Since you are dealing with the issue as far down the speed range as 15-20mph, I'd venture a guess that you are probably looking at the 1-2 shift solenoid. The slipping could easily be a result of the erratic engagement of the solenoid. Other than replacing the solenoid pack in the transmission (yes, its inside), I am not very well versed in the repair processes for the E4OD simply because I don't like them and their service record stinks. (I remove them in favor of some other transaxle). However, I do understand the Codes dispensed by the EEC-IV onboard computer.

Codes:
126 - MAP (Manifold Absolute Pressure) sensor voltage above parameters
327 - EVP (EGR Valve Position) sensor voltage below parameters
334 - EVP (EGR Valve Position) sensor voltage above parameters

None of these should cause the kinds of issues you are dealing with in this post but they WILL affect performance and drivability. Don't assume that just because a particular sensor is "throwing a Code" it is bad. There are other possibilities. Obviously, the transmission concerns are paramount to these but should you need help troubleshooting these as well, just let us know.

 

I had similar issues with my 94. Turned out my EEC was burnt up. I would take the 10 mins it takes to pull it out and remove the cover and have a look at it. You want to look for burnt up spots like below.





These capacitors seem to be the weak link. I have 2 EEC's that were burnt up exactly the same way from different bronco's.

To remove the EEC.

Disconnect the battery (Very Important)
Remove the screws holding the inner fender on the drivers side (6 x 7/32 screws)
Remove the cruise control servo from the fender (2 x 10mm bolts)
Remove the connector to the cruise control, lay it aside out of the way
Disconnect the ICM (ignition control module) and lay that wire aside.
Your removing these wires so you have some slack in the cable harness so it will be easier to get to and easier to get off.
Using a 10mm socket, unscrew the bolt in the center of the EEC connector, it stays in the connector so dont expect it to come out, the connector will just unplug as you turn it.
Remove the EEC Gasket (2 x 11mm nuts)
Wiggle the EEC out as far as possible, it will not clear the inner fender.
Using a 2 foot length of 1x2, press down on the inner fender just in front of the electrical box attached to the inner fender. Push HARD till it flexes down quite a bit. This will allow you to pull the EEC the rest of the way out.

Now that its out, use a T15 Torx driver to remove the 2 screws holding the cover on. Look for any burnt spots on the circuit board, especially near the surface mount capacitors (little silver cylinders).

If you find nothing, consider it a positive thing. At least you know its not that. I chased electrical demons for over a month before I looked at mine and found it all burnt up. Now that I have a good one in there it runs like new again.


EEC Connector


EEC slot - If yours is rusty like this, you need to find the water leak before it kills something important.