The X5 has just over 160k miles. It seems to work just fine after I hit 60 mph like I said, it just does shudder in the slower speeds. I was under the understanding that the converter doesn't "fully" (supposedly it never fully locks, it is supposed to leave like 3% slip or something like that) lock until it gets to 60 mph and that it uses a pulse width modulated solenoid valve to accomplish the partial lockup. I think what I am feeling is the converter lock completely when it is only supposed to partially lock and then it unlocks again real quick and that is why I get a shudder. This would be why I am questioning the solenoid valve. Has anyone ever seen this solenoid valve fail like this or has anyone even tried replacing it?

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2003 BMW X5 4.4i