I have a 1998 Buick Regal with the 3.8L V6 and 4T65E transmission. Car has 125K miles. I acquired the car when it had 98K miles and have no history on the transmission.

The first sign of a transmission problem was an occasional shutter that occurred on the 1-2 shift. That progressed to a regular shutter during the 1-2 shift and eventually the engine free revving as 1st disengaged and before 2nd engaged. At that point I hooked up a Snap-on scan tool but found no fault codes. So I did a reset and had the trans go through a relearn and then it was shifting correctly.

Without any further driving I then did a trans service and found that the fluid was not burnt - a good red color and very little accumulation on the magnet in the pan. While doing the trans service I installed a Trans-go shift kit. In addition to the shift kit I also added the heavier spring from the top of the 2-3 accumulator piston to the top of the 1-2 accumulator piston. The accumulator pistons also received new seals.

Now when the trans is cold it will act as if it is jumping between 1st gear and second gear on initial drive away and the 1-2 shift is sloppy with a free revving of the engine between the release of 1st gear the the engagement of second. Second does not seem to slip when it does in fact engage.

After it is fully warmed up (15-20 minutes of driving) it normally - but not always, starts off and shifts without issue. Also, warm or cold it will perform correctly if the gear selector is put in 1st and then manually shifted up to 2nd and then moved to the drive position.

Any thoughts on what the cause could be is greatly appreciated.

Sounds like the pressure control solenoid might be acting up, but usually when it goes bad it will set a p1811 but I have seen it not set the code and be bad.

Thanks for your response.

Yes, when I hooked up the scan tool I expected to see that code and maybe others but none were present. If I continue to drive it will it eventually set the code if it is the pressure solenoid? Will I cause damage if I continue to drive it?

Thanks

<<<@!1!@>>>

Yeah, it will start to self-destruct if you don't get it fixed. This guy on youtube has very good vids of how to replace the PCS.

Thanks - I'll check out the vids.

Update -

I dropped the trans (as shown in the videos posted by 75 racer) removed the side cover and replaced the electronic pressure control solenoid, both shift solenoids, the torque converter lockup solenoid, and the manifold pressure sensor - five total.

Test drive revealed the same basic symptoms although it seems to be a bit pronounced or worse than it was. Where before it felt like it was jumping between 1st and 2nd on initial drive away, now it shutters and sometime fairly violently. The 1-2 shift is more free wheeling and the engagement of 2nd gear is not as firm - now it kind of slides into 2nd.

Even shifting manually is not as good. Before it always shifted correctly when done manually where now it has the same lag on the 1-2 shift as when the shifting is automatic.

My understanding is when shifted manually the line pressure is boosted. So, when it was suggested that the problem was the EPC (Electronic Pressure Control) solenoid it made sense to me. Now it seems like the line pressure is running lower than it had been and thus making the symptoms worse.

Any suggestions on what I can do at this point is greatly appreciated.

It'* weird it'* not setting a P1811. If you have done the shift kit and the solenoids the only thing I can think of it the torque converter is failing but usually debris start to go through the trans when this happens and you need to rebuild the thing because crap goes through the valve body and gets stuck in the clutch drums. You said the pan was pretty clean when you serviced it and did the shift kit. Kind of a head scratcher??? The only thing I would suggest short of pulling the trans is trying a bunch of sea foam and a good flushing using Dextron VI other than that sounds like it'* time to disassemble this thing and have a good look.

Thanks for your response. Not what I was wanting to hear, but kind of what I was suspecting. While I am comfortable doing jobs like the solenoids, I don't have the tools nor the experience to tackle pulling the trans apart.

This car is used by my daughter while in college and she only has 1.5 years left and maybe 15K miles. That'* all this car needs to last.

How much sea foam would you suggest i run through it. Put it in and drive the car for a bit or just leave the car on the rack while running it for circulation and then do the flushing?

I would put one can in and drive it a few days maybe a 100 miles then flush it with dextron VI.

Thank you.