So here's the deal. I've got a 2001 4.8 and 4L60E swap in a 97 S10. Custom harness so it's 100% functional still being run by the 2001 silverado PCM.

Here's my issue, I had the trans totally rebuilt with a few upgrades like corvette servo, beast sunshell, better clutches, ect... When I picked the trans up, the guy said that he turned something up to make it shift harder. I don't remember exactly what he said though.


Anyway, I've got about 4k miles on the trans and it's acting REALLY weird. It used to hammer second and third and felt super crisp and responsive. Lately, it feels like it won't go into overdrive in the mornings when the trans is cold, second is no where even CLOSE to a firm shift accept for 1 out of maybe 10 1->2 shifts where it actually hits hard like it's supposed to. It feels like it lags on shifting gears sometimes.

It's really unpredictable. The weirdness varies each time it shifts. From what I've read, it sounds like it could possibly be an EPC solenoid issue. I also read that the EPC solenoid is what you adjust to manually up line pressure. Which makes me think that maybe that's what the builder was talking about adjusting.

What do you guys think? Could it be the EPC solenoid? What's the rate of failure on these things?

I'm hoping to figure this out before i end up smoking this new transmission.