1990 EB Bronco 4 speed auto / 5.8

OK - I took it in to replace leaking rad and to look at horrible exhaust. Mech replaced the rad, changed out a temp sensor - & it was running rich - then my cats clogged and so the cores were pulled out - both cats welded empty and re-attached. When I drove it home it would shuttle BAD from second to third back and forth fast at about 30 but only if I let off the gas at that speed. It didnt do this at all before the repair. If I turn off the elec OD on the dash it isnt as bad but starts to slightly lurch at about 45 mph like a stick shift at the beginning of your normal clutch release. Had a diagnostic done at another shop and nothing appeared to be wrong with it. I know I am a novice tho I have a general understanding of the mechanical end and for some reason this whole sudden tranny issue doesnt make any sense. I love this brute and much to the dismay of my better half I am keeping it, any help / ideas would be appreciated!
Note: had this only a couple years and as far as I know its all stock except the tires now 12.5 / 33

 

I'm sure the more experienced Bronco owners will pipe in soon.
But this sounds familiar to when I was having problems with leaks in my coolant system. Once all the leaks were fixed and the air taken out, it ran fine with no problems. Not sure why. Maybe it has something to do with the transmission rad/cooler.

 

What is your idle RPM?

You may need to do a tranny flush depending on how many miles are currently on your trans. Hopefully you did not get any dirt in the tranny from the radiator change. It can cause some pressure changes and the E4OD is fragile tranny when it comes to dirt in the tranny.

 

I have over 240K miles on it. It has a few ticks and groans but usually pretty solid runner. had the tranny flush last about 2 years ago when I first got it running. The idle rpm is lower now than it was before the repairs and fluctuating up and down from 1100 down to near-stall. Even tho I usually only drive it 2.2 miles to work then back, I took it off the road for a while till I figure out what is wrong.

 

Well the best thing to do is pull codes. The vehicle speed sensor on the back of the transfer case that mounts in line with the speedo cable can send a bad signal to the computer about shifting. The manual lever postion switch can cause the bad shifting as well. The hard shifting can be a computer mis shifting and not retarding the timing like it usually does with this tranny or you may have a bad u-joint in the rear or a bad u-joint in the double cardan joint at the transfer case output. A good way to see if it is a bad u-joint is crawl under the truck and lift up on the shaft and twist it a little. It may be good to do this with the rear wheels off the ground as well and the trans in neutral. Look for any play in the shaft at the joints. The double cardan joint at the output of the transfer case may be hard to notice this play. if the shaft turns a little before it turns the axle input flange or the output flange then you may have a bad u-joint. The manual lever postion switch and the Vehicle speed sensor are easiest diagnosed by pulling the computer codes either by a code reader or by the "paper-clip" method in a Haynes Manual or searching for it in the forums.

 

I had a diagnostic done and it showed no issues. Will check the joints this weekend.

 

toplessjeepchyck--
I have some ideas that might help. First, I am not a professonal or a real expert, but have done a lot of work on my own vehicles, including my bronco. I have rebuilt C6's/AOD's/C4's and have an extra E4OD that I have torn down and am rebuilding now (couldnt make a living at it, too slow ) The things I suggest, I have done to mine and it is working fine. I tow (not that often) a 26' boat ~8000# w/triaxle trailer, so I do work it and I am not very easy on it generally.

I put a Baumann shift in it at around 50K, because it was sloppy and slow shifting. It has done great.

On mine, the TQ Conv strategy seems to be controlled by MPH. Dosnt matter where your foot is, it locks up the converter at around 45 MPH. Really a pain when merging into fast traffic from an onramp. You loose ratio at a very bad time. I suspect the lockup strategy was probably about the same on yours. Since you are getting shudder at ~45 MPH, I suspect the TQ Conv, especially if it is the original. Check other things suggested also. I do not think it is the MIL sensor (my opinion only ) because if the tranny is shifting at all even harshly, its working, needs to be adjusted/changed, but working. The lockup soleniod in the tranny, from what I can see, is either on or off to lockup the converter. Probably wouldnt hurt to have the fluid pressures checked at the tranny. Remember that the OD can be "canceled", but the TQ conv locks up all the time, and locks at 45 MPH, so if it is slipping, it will slip all the time because you cannot control that function.

From what I understand, earlier models did not have "LUK" , or multiple clutches in the converter. They were famous for slipping and shuttering. I had to replace mine at ~125K because, on a trip w/a small, open U-Haul, the tranny overheated and blew most of the fluid out the converter seal. After cooling down, I refilled and continued to drive it until I replace the converter with a unit spec'd for an E350 ambulance. It has too much stall for my liking but works fine. I have changed over to Mercon V, which is supposed to help/cure shuttering. I do not have any shuttering from the converter clutches at all.

I just had an eratic problem that ocurred on cold start, before O2 sensors became active in strategy. After using a code reader, I replaced the O2 sensor plus the ECT sensor and the ECT sensor for the dash guage. It cured my problems. If you havnt replaced the O2 sensor (only one, and very easy to do) and the ECT sensor, thats right above the thermostat on the intake, consider doing that, especially the O2.

Until a real expert replies, this will give you something to consider. My experience has been pretty accurate, at least with my bronco.

Sorry to be long---lotsa stuff to look at. LOL anyway.

 

Ok well if i understand the problem you are having it IS the torque converter. I had a 94 f150 and my dad had one of the same year also. Around 80xxx miles or so the torque converter clutch starts to deteriorate and slip which feels like a shuddering or like you are driving over rumble strips. If this is what you are feeling then you either need a torque converter or there is a way to disconnect the torque converter lock up feature. I used to be a mechanic at a Ford dealer and on customer cars we replaced the converters but on our own we just pulled the wire out of the transmission harness for the tcc (torque converter clutch). It wil run and drive just fine but you will lose a little mileage due to the torque converter not locking up on the freeway. You will hardly notice a difference besides the increased rpms on the freeway.

 

Wilevel2----
Dont you go anywhere, your the guy I have been looking for Dont know how many people I have asked, but cant get an answer----other than a shoulder shrug!

I have the EVTM for the Bronco and know what/where the solenoid wire and connectors are. I have wanted to put a small switch on the dash, in the panel where the 4X4 switches are, that would manually control the Lockup solenoid. I'm was pretty sure that opening the wire to the solenoid would not cause a hard code that would cause "limp home" mode. What I have wondered, is will it cause a "soft" code, which wont hurt anything except having to look at a trouble lamp. I have designed a switch with a resistor to make the processor think it is still looking at the relay winding, when the leed is opened, but am not sure its necessary. Just havnt got around to "doin the deed" yet. I do want to keep the lockup feature, but under my control.

Appreciate anything you can tell me TX

 

benshere: What i did when i disconnected the tcc on my truck and my dads truck was to go under the truck and there should be a connector going into the side of, or top of the transmission. Then look at a schematic of the transmission wiring harness. Find the wire that goes to the tcc and match it up with the one on the connector in the trans. I just used a small pick and pulled the push pin right out of the connector. It was kind of a pain to get at but i was using a rack which made it easier. We just pulled the wire out and tucked it up into the harness and left it out, but i would imagine in your situation you could chop the end off, run a wire to a switch and back down to the end, then connect the new wire to the push in connector and put back into the transmission connector, should work like that. Oh and as for setting a code, the computer isn't smart enough to recognize that the clutch isn't engaging. If your truck is older than 96 it shouldn't be a problem, didn't set any codes in either 94 f150 i did it to.

 

wilevel2--TX, great to finally get an answer on that one. Now all I have to do is get off my backside and do it. I wish the TC would lockup at the top of 1st gear, then go into 2nd as usual for normal driving. Ive noticed several things the engineers didnt as me about first!!