Thread: P1811 will not go away

Got a buddy a few towns over I've been trying to help out with his tranny. He had it rebuilt for P1811. It was good a little while, then P1811 showed up again.

After the original rebuild, here is what has been done by the tranny shop in an ongoing effort to keep P1811 and harsh shifts from popping up.

PCS 3x
Valve body 2x
some kind of piston
surecure kit

I'm not sure of what the piston was. He just e-mailed me that little list. Probably accumulator piston or something.

Anyone have any ideas? Keep in mind the above parts were after a rebuild.

input piston maybe? do u know if they used the borg warner pcs?

Originally Posted by gtpinsc

input piston maybe? do u know if they used the borg warner pcs?

I don't. I don't think he does either.

Well there it is in plain sight as a reality..... Rebuilding a transmission is NOT the correct answer to fix a P1811, something causes it and that something must be addressed rebuild or repair and though most transmissions work fine without the code there is likely still a problem. What car was this transmission built for, what pcm, what engine, what mods if any? The Transgo shift kits greatly help this problem because of the accumulator spring setup they use. Stock 4T65E transmissions have very weak 1-2 and 2-3 accumulator springs and while giving a very long smooth shift fee they also make the pcm work towards the high end of the adative shift tables. The Transgo springs and spacers keep the accumulators from having to max out slowly before a shift completes and greatly quickens up the process which allows the pcm to scale back a lot on the adaptive shifts which leaves a lot more headroom to help prevent a P1811. Another thing that works against this problem is the extremely loose clutch pack clearance from the factory on the 2nd and 3rd clutch packs and tightening up the clearances on these two clutch packs makes a big difference in shift timing shift kit or not. I have not seen this transmission so I cant vouge for what was done or not and how it was built but there is always a possibility of a torn sealing ring, crack in a casting or drum that was overlooked, etc. There are an aweful lot of variables that can cause this problem but after the pcs is ruled out then the accumulation system is next in line to check out

i wish i had ur knowledge trannyman

I am working on a 98 Regal GS with the same code that pops up. I did a Gen5 swap on it and had some issues with the IC core so it's been sitting awhile. I just started driving it again, but the code hasn't shown up yet.

It was a stock rebuild. Nothing performance. Car is a stock 3.4L 2003 Impala.

I'll pass on the info you gave me and maybe it'll help him out. Thanks.

Originally Posted by 19SE92

To the Op have your friend confront the builder and ask him if he changed the EPC solenoid.

EPC = Electronic Pressure Control
PCS = Pressure Control Solenoid

They are one and the same. It was changed three times.