Random Shudder

[87mefull]

My car has a random shudder, feels like almost a torque convertor shudder or like the torque convertor tries to disengage to downshift. It will do it in OD at random speeds and sometimes in 3rd at low speeds. Mainly, it will shudder randomly when I try to maintain a set speed such as 65mph. I did adjust my tv cable to the max setting and my car shifts great. I worked on the car today and tried to find a miss but I couldn't detect one and the engine runs smooth.

[Lincolnmania]

check your universal joints

[AOD]

Have you calibrated your throttle position sensor ever? I had a shudder around 45 MPH cruise in 3rd and the TPS calibration fixed it. I had only 0.8V (should be 1.0V) with key-on.

Keep the car out of OD unless you're on the highway and you will have less OD/D shift shudder.

~Adam

[87mefull]

TPS is brand new, I replaced in June after I upgraded to an HO upper/tb, intake spacer, etc. It should be still set to .99 volts, which was the max setting I could get out of it without damaging the sensor. Could have failed though so I look into it.

The shudder has been a recent problem, it started to happen on saturday. It doesn't matter if the car is in OD or not, it will shudder if you maintain a set speed. I drove at 35mph in D and it shuddered every couple of seconds the other day and it did the same thing at 65mph in OD. Shifts great though (set it to TV max 3 weeks ago) and has plenty of power for a lopo.

The thing I noticed is that its not too bad if its just me in the car, doesn't do it often. If there is 3 mid-big sized people in the car, it will shudder harshly and the car becomes hard to drive. I'll check the u-joints though, pretty sure they are probably original.

[AOD]

it will shudder if you maintain a set speed.

I hear ya. Check the TPS and then the u-joints as Scott mentioned.

Does the shudder go away if you give it gas or let off? (this would rule out a tire vibration) Prolly wouldn't hurt to make sure your tires are properly inflated, as the cold weather comes in tire pressures drop.

~Adam

[turbo2256b]

Have you checked for rust holes in the frame around the trans mount crossmember. They can be on the top of the frame also were you cant see much have to feel

[87mefull]

Frame is clean, I undercoated it and it was a florida car until last year. Tranny crossmember looked solid but I don't have the tools or a jack to look underneath the car at school. I'm going to check the engine mounts also if I can't find anything else.

Actually I described it wrong previously, its not really a shudder, its a harsh bucking that lasts only a few seconds at random times. Just happens sometimes when my foot is on the gas trying to maintain a set speed, but it gets worse the faster I go. I drove to work today and it started bucking as I slowed down from 50mph to 35mph with my foot off the gas. It bucked harshly again at 45mph at random then didn't do anything for another 15 minutes until I shut the car off. I did notice that the transmission no longer slips when I slow down from 50-40 or 35mph. Its allways had problems downshifting from 4th to 3rd, even after I adjusted the TV cable to the max setting and added some fluid.