Didn't want to hijack another thread (see below)...but I have a similar situation/questions:

https://www.ford-trucks.com/forums/4...overdrive.html

I've had a 1994 Bronco 5.8 liter automatic (230,000+ miles on original motor I believe) for 2-3 weeks now. I've had it out on the highway a few times and it's started what I would call shuddering. It reminds me of my youth when I'd try to accelerate in too high of a gear in my little 4 cylinder 5 speed Ranger: it would be driving along fine until I tried to speed up and then some vibration, shuddering/stuttering, poor acceleration, etc. I have only noticed the Bronco doing it around 35 or 40 mph and higher...

I assume my tranny is the E4OD based on the push button Overdrive on/off on the shifter. I read the thread I linked above and tried what someone mentioned (getting up to highway speed, keeping my foot on the gas, and tapping the brake). That seems to stop the shuddering for a moment, but it doesn't seem to completely stop it and it comes back when I accelerate again. I also tried accelerating harder when the shuddering happens and when I did that it stopped. Also, on the highway today at 75mph I came on a little hill with the cruise on and it started the shudder as it tried to maintain speed. I pushed the Overdrive off and it stopped doing it once the transmission downshifted.

I've got a lot going on right now and probably won't be driving it much, but my plan when I get to it is to change out the spark plugs, wires, distributor, etc. and see what that does for it. Is there something else I should try first? If the spark plugs, wires, etc. doesn't do it, what/where is the next step to address this? Should I just take it straight to a transmission shop? I am a pessimist so I'm assuming if I take to a tranny guy he's just going to tell me it needs to be rebuilt/replaced. HA! Any thoughts or suggestions you guys have would be appreciated. Thanks!!

 

It is almost certainly an engine problem, not a transmission problem. The plugs, wires, and possibly the coil are the places to start.

 

Mark is the guru here.

My only concern is the turning off the over drive and it going away. I have had a torque convertor slip and cause the same type of vibration. I cannot honestly remember the speed that it did it, sadly it was in 96 or 97 when I was still working in a Ford garage.

When is the last time that you did a tune up? Possibly look at the plug wires also, when they get under a load it may cause the spark to jump from a boot or even the wire if there is an unknown crack. Does it run worse in the rain, the splashing of water will affect it and show it more.

Good luck, be sure to post up what you find out.

 

Finally got around to attempting changing the spark plugs, wires, and distributor cap, and rotor. I've never done this before, so I'm guessing it took WAY longer than it should have, but I seem to have pulled it off. I test drove it (in town and highway) for about 20 minutes or so. It definitely is an improvement as far as how it seems to run (5.8L automatic).

Here are the spark plugs I took out:






All of them came out fairly easy but every one was rusty and the electrodes were rounded off and black except one that was more ashy colored. I didn't see any problems with the wires but I replaced them and the distributor cap. I would have replaced the rotor but when I pulled the new one out of the box, it was about an inch to short compared to the one already in there.

Now, here's my new, errr, old dilemma: it still shudders on acceleration. It seems better or at least not as hard of a shudder/vibration, but it still happens. It doesn't happen from a stop and hasn't happened yet under 35 mph. For example, I'm driving 50 mph, I lightly accelerate and it starts. I give it harder acceleration, the transmission downshifts, it stops. I also tried just backing off the accelerator when it happened and it stopped.

As I said above, someone mentioned in another thread about getting up to highway speed, keeping my foot on the gas, and tapping the brake. I did that before the tune up and it sort of stopped it but it came right back. I did that same technique/idea tonight and it seemed to work. Around 55 mph the shuddering started, I kept my foot on the gas, tapped the brake a bit, the rpm gauge jumped 400-500, the shuddering stopped, and the rpms went back down.

I don't know what the shuddering/vibration means, but it's not terrible. I guess I'm hoping someone may point me in the right direction. If it is a torque converter, I'm not about to try that, so what does something like that cost to be replaced?

On another note, I figured I'd take back the baby rotor they gave me on accident and get the correct one. I didn't get a new coil...is that something I should go ahead and get or just not worry about if it's not causing an issue?

 

That suggest one injector is dirty so cleaning or replacing them all is a good idea. The plugs should be tan colored normally so this also suggests the motor is running rich overall, has the O2 sensor been replaced? If not hold off doing so until you address the injectors or the shudder problem is likely to get worse.

Shudder under light throttle like that again suggests fueling is lean somewhere, does the motor have any exhaust leaks?

 

Hmmm, I don't know (about the exhaust or the O2 sensor). Based on the condition of the plugs, I'm guessing the PO hadn't done much to it in awhile. I am taking the old girl to a mechanic on Tuesday to have it looked over. I will mention the issue to them and see what they say.

 

Well, the mechanic's look over didn't break the bank. In summary, they changed the oil and filter, looked it over, and drove it to experience my shuddering complaint. Guess everything looked good overall except the brakes and one of the front shocks is held on with wire in place of a bolt. A rear brake pad was "in pieces" and he thinks at certain speeds it may catch/engage and that be the shuddering. He took off the pad completely and it still does the shuddering so I assume that wasn't the issue. I'm having the brakes done next week and am going to wait until warmer weather to replace all the shocks. Anyone have any thoughts about where I should start next (to fix the shuddering)? I thought I might find someone to look over the exhaust and possible do something to fix the very tame sound that is currently my exhaust note. I don't want it to be loud and obnoxious, but I also would like a little rumble to it.


Quick question: I obviously need at least one bolt for the shocks and based on their appearance (all of them are completely covered in rust), I'm figuring I'll bust something getting them off. Where can I get replacement hardware?

 

Any parts house should have replacement bolts, nuts etc. Probably have to take yours to match them up becasue they wont know a thing about what size, thread etc. I suggest buying some anti-seize also and save yourself some trouble if you ever have to tear back into anything.

 

Ever used a code reader on your Bronco to see if anything pops up?

 

Just an additional thing to look at too is your fuel pressure. I've driven some vehicles before with a failing fuel pump that had somewhat similar problems.

You usually can rent a fuel pressure test kit at your local parts store for "free" to make sure the pressure is in range. Also, it would be a good idea to change your fuel filter if it hasn't been done recently. As Conaski said, your plugs do look like they may have been running rich though, but testing fuel pressure would still be a good thing to rule out.

Shuddering in my bronco however has almost always come from an ignition problem however. I've had wires touch my headers more times than I can count so it may help to very closely inspect each of the wires, especially at night. I believe you said you changed your wires, make extra sure they aren't touching your exhaust manifolds or arcing across each other.

 

Watch your speedometer needle for bouncing. Mine bounced between 30-40 and shifted erratically, shuddered while decelerating and died at stop lights. Replaced the speedometer head (PSOM?) and it cleared right up. I did do a complete tune-up and replaced many sensors before finally finding out it was the speedo at fault. I have a great running engine and many known good sensors in my tool box now...

 

It very well may be an engine condition. However a common problem on the E4OD is torque converter shudder. Check the condition of the fluid

 

4R70W is the trans that commonly has torque converter shudder. It's possible, but very rare in the E4OD.

 

I appreciate the help! I honestly have moved the shudder issue down my list and am currently working/fighting with the ***-end now. I broke out the back glass, so I'm searching for a replacement (may have found it) and last night I started tackling the spare tire carrier (putting it back on). I guess at this point, I'd love if someone could give me some ideas of where to start as far addressing possible culprits.

I had the brakes redone recently and was told the ball joints are bad. Doesn't seem like that would shudder only upon acceleration though.

Are there some "smaller" things I can start replacing and work my way up until I find the problem?

 

Did you ever check the condition of the transmission fluid? Wouldn't hurt to have a new filter and fresh fluid. I had a condition in the past where mine would shudder some going up hill, only in overdrive at higher speeds (over 50 MPH)as i started getting into the throttle to maintain speed. Dropping out of OD would stop it as well as letting off the gas. I changed my fluid and filter and never have had that problem again, for 7 years now.