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Can someone please explain "transmission shudder"?

R

redtires

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Sep 16, 2008
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In that place when your falling in a dream, and yo
I ran a search for this, but only came up with three or four results, that all had to do with shudder in the engine rpm's.

The car: '95 mystique w/ duratec/ CD4E atx and 96K and some change on the clock. I do have an intermittent CEL, and I'll get codes for that tomorrow, which is the start of my weekend and I'll post them for any review. New air filter and gas cap (by me).

The problem: Car drives great 90% of the time, but seems to have an issue with upshifting when under load, e.g, going down the highway at 65mph...come to a hill, normally the car would kick out of OD and ups the rpm to maintain speed...but it will try...try...try....shift. I can "trick" it by hitting the green OD button on the shifter, and it shifts then, no problem, then just hit it again at the top of the hill and the rpm's will drop back down into the OD range. So, not sure if it's a solenoid, band....or if the fluid is toast. I have not checked it yet as I am off to work here in a few minutes (taking my other car). The current plan is to do the 3x tranny flush with mercon and have the codes pulled and posted.

I love driving this car, so even if the tranny is toast, I'd do a rebuild/replacement if needed....of course, I'd like to get through the rest of the year before having to do that if need be. With less than 100k, I think it would be worth it.

Anyways, if anyone can shed any light on whether or not "shudder" is what I am experiencing, super! Thanks!
 
Doesn't sound like anything has completely broken, so I would point towards needing some new fluid. Do a FEW drain and refills, not just one. You will need to either refer to a Haynes/Chilton to find the EXACT drain/refill volume, or you can measure the amount drained and replace that exact same amount.

Make sure to post up your CEL's
 
That doesn't sound like trans shudder. What you have described may even be normal transmission activity. You would like it to downshift a little sooner when crowding it climbing a grade and you figured out how to do that.

If you are experiencing a little engine stutter under that kind of load, you may have worn plugs or possibly dirty injectors. It would not hurt to catch up on any tune-up maintenance.

Trans shudder with this transmission is usually from the torque converter trying to lock up, most usually on a 3 to 4 shift, at about 35 to 45 mph. The sensation (and noise) is similar to running over a rumble strip as you have started to stray off a freeway. Instead of locking up, the torque converter lock up clutch chatters as it tries to lock up. The most common cause is worn fluid that has burned up or consumed the friction modifiers in the fluid. The fluid is no longer as slippery as it should be and the clutch grabs instead of engaging smoothly. Unless this has been happening a long time, it is nearly always cured by changing the trans fluid. You should do that at least every 30,000 miles anyway, so do it as maintenance even if you are not experiencing the problem.
 
aaahaaa....well that is some very good feedback, thanks Jim and zorrex. I may as well do the fluid change as I really don't know the last time it was done. And Jim, that is really some interesting information. It definitely is not anything like a rumble strip, so this makes sense that the hesitation would be more likely plugs or fuel related. I'll certainly go with your suggestions. I do realize that the tranny is supposed to shift when climbing, but what is throwing me off is the apparent stutter, which really is a better description btw, but I wasn't sure if I was overriding the problem with the OD switch. I've got a Haynes manual, so I'll be referencing it for the fluid change...but I know it's here too...thanks for the great info!!!!!!!!!!!!!!!!!!!!!!!! I'll still post codes and let ya all know how it's going.
 
I spent 6.5 years as an auto trans engineer.

Shudder is common with torque converter issues, during lockup engage or during high loads just shy of having the T/C unlock.

Water (coolant) in the ATF or burnt fluid can cause issues with the friction additives in the fluid. If the fluid is burnt, you have other issues to worry about, like smoked clutch packs that could be the result of valve body issues like wear or debris.

If the problem is a T/C slippage issue, you will probably see a code for input speed. Maybe a P0716?

P0715 Input/Turbine Speed Sensor Circuit Malfunction
P0716 Input/Turbine Speed Sensor Circuit Range/Performance
P0717 Input/Turbine Speed Sensor Circuit No Signal
P0718 Input/Turbine Speed Sensor Circuit Intermittent

As you climb a hill, tip into the throttle a bit (not enough to cause the engine RPM to increase due to T/C unlock or 4->3 downshift) and tap the brake gently (just enough to get the brake lights to come on). This will cause the T/C to unlock. Play around with it and see if you can reproduce the issue with just the T/C disengaging/engaging while in fourth.
 
Ok...so I ran the test and came up with a code 332, which leads to a faulty EGR valve, so I'm assuming that is the reason for the CEL, and the fact that it does not come on until the engine is warmed up. So, I'll give that a try and see what happens. But I've got another question now...I checked the ATF, it doesn't look or smell burnt...not little "floaties" in it, etc....but isn't mercon supposed to be red, or is that only type F??? This stuff looks more yellowish or clear-ish.
 
redtires said:
Ok...so I ran the test and came up with a code 332, which leads to a faulty EGR valve, so I'm assuming that is the reason for the CEL, and the fact that it does not come on until the engine is warmed up. So, I'll give that a try and see what happens. But I've got another question now...I checked the ATF, it doesn't look or smell burnt...not little "floaties" in it, etc....but isn't mercon supposed to be red, or is that only type F??? This stuff looks more yellowish or clear-ish.
Click to expand...
Yes, the fluid should be red. Definitely do multiple drain and refills, but DON'T do a flush. Flushes on older trannies that haven't had a fluid change in awhile could potentially dislodge larger particles and damage the transmission. It isn't worth the risk. Also recommended is changing the spark plugs and wires.
 
The fluid is more or less red depending on how much dye is put in it. To save money, less dye may look a little pink (Walmart "Supertech" brand). With use will start going orange then brown. Dunno what you got but I'd be changing it. Bigjim, that rumble strip analogy is a good way of expressing the shudder. This guy's car appears to be a '95, so slipping converter clutch code may be 628 (3 digit EEC-IV).
 
Well, I did not get a 628 code, but I did get a 332 code, which points to a fault in the EGR system. I just ran out of time today, so I'm going to do the plugs and wires and the transmission tomorrow. I've been doing some reading up on the IMRC going bad, but it appears that this is not a hugely common deal, although maybe it is...don't know, but I'll look anyways. I'm gonna figure this bugger out or my name isn't rumplestillskin....oh wait....craaaaaaaaaap!
 
redtires said:
Well, I did not get a 628 code, but I did get a 332 code, which points to a fault in the EGR system. I just ran out of time today, so I'm going to do the plugs and wires and the transmission tomorrow. I've been doing some reading up on the IMRC going bad, but it appears that this is not a hugely common deal, although maybe it is...don't know, but I'll look anyways. I'm gonna figure this bugger out or my name isn't rumplestillskin....oh wait....craaaaaaaaaap!
Click to expand...

As far as the 332 (same as P0401 in 96-00 modles) code is concerned, pull the throttle body and clean your EGR ports before doing anything else. They get clogged with carbon buildup and are the most frequent cause of this problem.

Do your tuneup. There's no evidence in what you've reported so far that there's a problem with your transmission. Give it some fresh fluid anyway, won't hurt. Once you fix the other problems, go back and install an auxiliary cooler to extend its life.

Steve
 
Wow.....I mean.....wow....I never knew that just changing the plugs and wires could make such a HUGE difference. I also pulled the TB and....good lord.....there was a ton of gunk on the back of the plate!!! Cleaned up very nicely with some B12 and a soft nylon brush. There is absolutely no hesitation from the get go, idle's great both in P and in D at stops and such. Drove it around town and on the interstate and it ran great. I do however still get a CEL once the car warms up....I still have to put the scanner back on it to see if I'm still getting the 332 code. So, thus brings me to my question; The EGR ports...I'm not too sure I actually got them. There was one hole on the back of the TB, on the same side as the TPS (I think that's the TPS, on the side of the TB). Did I miss some ports that would be behind the gasket??? I didn't take the gasket off of the UIM, as I could not get a new one from any of the auto parts stores in town. But I did not see any other openings other than the TB body itself. The green hose appears to be intact, but I can always check it again. I need to do an oil change either this afternoon, or tomorrow morning anyway, so I will check the EGR tube at at the cat while I'm under there, other than that, can't think of any other EGR parts to check. And, before you ask, no I have not done the fluid in the tranny yet...but it will be done soon...I've got other things to do ya know! ;) At any rate...I really, really want to thank you all for the great feedback and tech knowledge, it's just super to be around helpful people with common interests. I love my genIV Taurus, but the mystique is just plain fun to drive...so my bull may get a lot fewer miles this year :D
 
Yes, the passages behind the throttle body gasket need to be checked and cleaned. I have had my throttle body off a few times, including to check those passages a couple of months ago, and still have the original gasket. I've had no trouble using it over again. Remove it carefully.
 
If you got some antiseize compound laying around, it will definitely make that gasket come off easy. I reuse my gasket too.
 
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