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rvray

Sc 400

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I have had several Lexus over the years. This one is a 1995 SC 400 with just over 90,000 miles. It has had all the motor mounts replaced. It has a shudder when driving specially when you let off of the pedal then re accelarate, seems to be comming from the bottom center of the car. Any suggestions? The car has a very good local maintence history no accidents etc.

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I have had several Lexus over the years. This one is a 1995 SC 400 with just over 90,000 miles. It has had all the motor mounts replaced. It has a shudder when driving specially when you let off of the pedal then re accelarate, seems to be comming from the bottom center of the car. Any suggestions? The car has a very good local maintence history no accidents etc.

You first need to tell a little more about the history of maintence please. If you have checked the wires, caps, rotors, and plugs, I would start with possibly a vaccuum leak somewhere. It has been known to be a little one to cause the symptoms you are describing. Furthermore, there have been instance where the IAC (idle control valve) is not working like it should, as well as the MAF (mass air flow sensor) is dirty or not working at all. I had the same problem, 92 SC400, and it was it was bucking when you off of the throttle at ANY speeds. It drove me nuts. I first thought it was the rear end bolts from the axles loose again, but it wasnt. It sounded like it was from under the car.

I ended up cleaning the MAF sensor, adjusting the TPS (throttle position sensor), and the TRAC sensor. It bucked for a second or two when I first put everything back together. Then I floored it a couple of times and it seems to have worked out, no more bucking. I just experienced this the last three days and did the above things this afternoon, and it drives fine now. Silky smooth. I hope this has given you a direction to attack this, and let us know what you find out.

Is there a CEL or trac light on or flickering?

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I have had several Lexus over the years. This one is a 1995 SC 400 with just over 90,000 miles. It has had all the motor mounts replaced. It has a shudder when driving specially when you let off of the pedal then re accelarate, seems to be comming from the bottom center of the car. Any suggestions? The car has a very good local maintence history no accidents etc.

I have a '95 SC400 with 182,000 miles and similar symptoms... a slight vibration when accelerating and a roar or slight shudder when decelerating. There is also what appears to be a bit of 'slack' in the drive line detectable when getting on and off the accelerator at speed. I've been told these symptoms point to a deteriorated drive shaft center bearing support. The center bearing support is a rubber mounted bearing that stabilizes the two piece drive shaft and can be replaced. Universal joints are also a possibility, but these, I am told cannot be repaired and are less likely to be the cause. I have not yet attempted to make the repairs, and would be interested in second opinions.

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