In my 4 runner when I slowly accelerate between 30 and 40 mph just as I can hear the car about to shift gear the car begins to shake when I than accelerate the shaking stops. Brought it to a shop and they changed a spark plug and coil they say was mis firing, but I pick the car up and the problem is still there. Their diagnostic shows no problems, yet the shaking is still there when slowly accelerating between 30-40, no check engine light has ever come on. While it shakes if I shift the car from D to 4 the shaking stops, and if I speed ahrd through 30- 40 it dosent shake, just when I slowly accelerate. Please help
This is just a guess, but I wonder if it is the lock-up feature of the torque converter that is causing this. When the converter locks up, the engine is connected directly to the transmission and this avoids the slippage in the torque converter which saves gasoline. When you downshift, the converter lock-up is disabled and hence the vibration you are experiencing disappears. The 30-40 mph speed would be about right for the lock out of the torque converter to occur.
I believe that Triedaq is right on target regarding this being a problem with the transmission’s torque converter lock-up mechanism. The speed range that was mentioned, as well as the shaking that is felt, supports this probability.
The OP needs to take his vehicle to a well-reputed independent transmission shop for complete diagnosis and repair. Whatever you do, do NOT go to AAMCO, Lee Myles, Cottman, Mr. Transmission, or any other chain operation–unless you want to be told that you need a new/overhauled transmission, whether you really do or not. An indy trans shop is much more likely to give you an honest diagnosis and a fair price for this repair.
While you have the car at the trans shop, have them also do a fluid and filter change, unless you have already done it within the past 3 years or so. Trans fluid should be changed every 3 years or 30k miles, whichever comes first. So, on the basis of elapsed time, you should have had the trans serviced at least once already. And, if you have over 60k miles, it should have been serviced twice by now.
If it is close to the 6 year 60 k power train warrenty, take it back to the dealer if service does not solve the problem. When you are close to warrenty expiration Toyota customer service, not the dealer will always consider reimbursing you. If I am close to warrenty coverage expiration from either Honda or Toyota , I always get the manufacturer to cover the cost. You mess with an independent before you try…you are on your own ! A year or 10 to 15k miles is well within going this route.
Disconnect the TCC connector to verify the TCC is causing your problem.
Newer cars do not have a tcc connector. They have a much more complicated wire harness routed to the trans. That idea might work on a 84 Buick.