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This sounds like you might need to do a couple of things on the 4l30e. In GM 4L30-E (AR25 and AR35) units the OE boost valves are made of steel, whereas the sleeves are made out of aluminum. Over time the valve wears against the sleeve and causes boost pressure leakage. The result is low line pressure during boost, with associated burnt clutches. Sonnax boost valve and sleeve kit 54200-14K restores pressure control to the boost circuit.
1. Remove OE boost valve and sleeve valve train. 2. Discard OE boost valve and sleeve, while retaining other parts for reuse. 3. Reassemble using Sonnax boost valve and sleeve.
Also make sure the Low Band Adjustment is correct> Recomended Low Band Adjustment on a 4L30-ETorque the pin at 40in.lbs. then back off 4 turns. Then tighten the counter nut.