95 Taurus accelerate shudder

My 95 Taurus SE shudders when engine is hot and when accelerating, around 35-45 MPH. Changed and flushed ATF but did not help. otherwise the car runs great. No warning lights. Any idea?

Could be a misfire or a transmission on its way out. When I had an injector stuck open (still doesn't work all the time), I had some shuddering under accelleration.

Just as a question, what fluid did you use? Mercon IV has some sort of additive that prevents shuddering. Mercon III sometimes causes shudders.

Thanks. Mercon III was used as recommended. The symptom shows up very regular, always be when engine is hot, accelarating around 35 to 45 MPH, by the way, it happened more frequently when going uphill than other situations. Gonna check Engine performance first.

Almost has to be in the tranny and did they find anything unusual on the filter? When it was flushed did they drop the pan and clean or replace the filter? The valve body might have some dirt in it and having it cleaned might solve your problem. Lucas makes an additive that supposedly stops shudders and you may want to consider adding a can. http://www.lucasoil.com/products/display_products.sd?iid=29&catid=2&loc=show

"it happened more frequently when going uphill than other situations."
When the tranny gets a load on it it slips causing the shudder and the more it slips the more it heats up. Friction = heat. I wouldn't drive it that way to long 'cause you could make a simple problem worse thus costing more money for the repair. Take to a tranny shop and ask their opinion or the Ford place.

Thanks Huney1. The oil pan has been dropped and a lot of muddy like stuff have been cleaned out. There is a megnetic ring in the pan and it trapped a lot of metal particles. The filter has been changed. The oil was brown and burnt. The mechanic did not find any other problem when flush the oil and the car was running fine for 4 months after that. The shudder just happened couple times when in the speed range, going uphill, and when engine is hot. When the speed is higher than 45, it just gone. My guess is that whether the engine is running rough when it gets out of limp in mode (perhaps an emmision compnent bad), valve body problem, or torque coverter clutch problem. I high suspect the valve body issue as the car will not shudder when cold. I will try the fluid you suggested.

The difference between Mercon and Mercon V is the V is part (half?) synthetic so costs more. Suppose to stand up to heat better and change it about half as often. General rule of thumb is; Mercon V can be used for Mercon but Mercon can NOT be used for Mercon V. Mobil makes a full synthetic tranny fluid and I put six qts in mine and it does shift smoother. As to whether or not it would help your shudder, I can't say but the Lucas addative says that on the label. One thing Lucas says is you can add it without draining out some travvy fluid, but I thought overfilling was a definite No No.

I used the Lucas and it seems stopped the shudder. I will drive longer during the weekend to see if the problem solved. Thanks Huney1!

"I used the Lucas and it seems stopped the shudder."
Good deal David! I read the label and that stuff does more tiricks than a Circus show dog. :iagree:
Heck yes, that Bull might run another 25,000 miles. Hope it runs a lot longer and at least it gives you heads-up time to save some money for the rebuild. I haven't priced one lately but I think they run $1500. anyway. Shop around and don't be shy about asking for references and call them. Another good place for referral is auto parts stores and used car lots. Whatever warranty they offer - GET IT IN WRITING!

I'd check the fluid when it's good and hot and if it's to much overfilled I'd get a piece of tubing and run down the dip stick hole and siphon some out 'til it's at the proper level. I let mine siphon all night and got out everything in the tranny pan and replaced it with 6 qts of Mobil 1 full synthetic fluid.
(Can't remember if it was 5 or 6 qts, but close enough.) Certainly not the cheap stuff but I declare my tranny shifts smoother and never hesitates.

Oh woe is me, Oh woe is me! Gas just hit $2.40 here in SC near Savannah, GA and that's the highest it's EVER been.

I hear a lot of people complaining about the Lucas stuff ... I've been using it for ~15000 miles and it's great stuff.

This would make me think twice about additives in my engine oil.
http://www.bobistheoilguy.com/images/lucas/lucas.htm I wonder if STP does the same thing frothing up and gets full of bubbles? One thing for sure, air bubbles in engine oil is bad JuJu. :uhoh:

My power steering pump was whining and I put some Lucas in but didn't help because some pump valve was blown. You guys got me thinking and I mite have to put some Lucas in my tranny for preventive maintenance medicine.

I put some lucas in the power steering resovior and I didn't notice it doing anything ... I only put in a few drops.

Engine oil additives are supposed to clean the engine, right? ?Lucas doesn't clean the transmission, just plays with the fluid in it somehow ... so I guess it's somewhat different of a concept.

I doubt it has detergents strong enough to melt off the crud build up inside the tranny because if it did the filter would clog along with those little valves in the valve body. A'while back someone said when you get a flush you should always ask them to clean the valve body because that's where the crud particles get caught up and cause a problem.

Before summer I'm considering siphoning out another 6 qts and refill with 6 qts of Mobil 1 full syn 'cause the full syn suppose to tolerate and disperse heat better than Mercon V.

I just remembered something. Back in the early 1950's my Uncle had an old Plymouth sedan, straight six with sitik shift, and everytime he filled it up he put a quart of ATF in the gas tank. I remember him telling Dad something about it helping the valves and rings, or something along those lines.

David, question for ya'; When they cleaned the tranny pan, . . . did they flush the torque converter as well? Reason I ask is, the flouid you described sounds pretty nasty and leads me to belive the fluid inside the torque converter is equally as rank. If they clean the pan and flush the converter it takes about 16 qts to refill it. On the other hand, to drop the pan and replace the fluid and filter is like 6 qts. So it leaves 10 qts of nasty, old fluid in the converter to mix with the 6 fresh qts.

Now then, if you do a change every 30K miles you could probably go to 60K and change it again then go to 90K before the big flush. That would depend a lot on where you live, driving condtions and how YOU drive it.

So, what I'm wondering is IF they only changed 6 qts and you have 10 qts of nasty left in it then the shudder may be caused by some crud left in the 10 qts. If my numbers are correct, they only refurbished/replaced one-third of the fluid. Catching my drift here?

You can get tubing at a parts store small enough to go down the ATF fluid dip stick tube, get about six feet to make sure. Don't stick it in there with it real hot, let it cool to luke warm then siphon some out and compare it in a glass container next to brand new fluid and see what it looks like. Smell it and rub it between your finger tips and evaluate what you see, smell and feel.

OK, my movie is coming on so have a nice evening and I hope we get that Bull of yours straightened out. Bull = Taurus, Taurus the Bull. Get it? :slap:

Speaking of atf in the fuel tank, on our cars, 60's and early 70's, we used to dump Marvel Mystery Oil straight into the carb until the car would stall, leave it there for like an hour, supposed to be a super cleanup of the topend of the motor,, plus there was nothing like the stupendous cloud of smoke generated as we cleaned out the oil... air pollution, what was that?? PCV valve, huh??? Straight pipe crankcase venting was the ticket.. I know guys that use atf in their diesel trucks supposedly to keep the injectors clean