Help with Transmission

[chrissbee77]

Okay so i just got my 01 grand prix gt 3.8 n/c back form the transmisison shop. It has 158,000 miles on it. I thought it was acting up shifting a little wierd but nobody but me seemed to notice it but me. (shifting from i think 2-3 or 3-4 it seemed to take a little longer) the shop said something with the valve body causing it to do it. he then told me that the engine was overcompensating for it and throwing a code but i did not see one he said he scanned the trans but i did not get the code from him (my fault) he is calling for a complete rebuild 1,265.48 that includes parts and labor (how nice) does this seem right or should i just drive it until it gives and then buy a new one. I know nothing about transmission so i dont want to think i'm being taken for but you never know like i said just want so honest help thanks

[troy1]

Long shifts usally point towards a bad PCS. Does it shift hard after the car warms up? also you need to find out if the code was a p1811

[maxwedge]

If you go for the repair, get a confirmation in writing the overhaul will correct your specific your shift complaint. troy1 is correct about shift solenoid issues being common on these units.

[chrissbee77]

how do i go about changing the solenoid and is there a link to do this. I have very limited skills. but am a quick learner. What parts do i need and where should i get it (them ) from thank you everybody

[BNaylor]

Since you have limited skills forget it. This is not a typical DIY job since the engine/tranny must be dropped on the subframe and tilted to remove the side cover assembly just to access the shift solenoids and pressure control solenoid. Plus a whole bunch of components have to be removed or set aside before that.

As suggested did you confirm the DTC was a P1811 (max adapt, long shift)?

[SyntheticShield]

You can only change out the solenoids by dropping out the transmission or Ive seen it done where they loosen up the cradle on the passenger side, totally drop it as far as it will go on the drivers side and then pull off the side cover so you have access to the solenoids.

Of course you'll have to either separate the tranny from the engine or support the engine from above with an lateral engine support. Its an involved process to do it in the car.

[chrissbee77]

I have not confirmed a code yet. I wil take it to another shop on friday and post the results from a (computer scan?) if it is a p1181 what does that mean and is there ANYTHING that i can do besides having to replace or rebuild i love my car but only have about 125 or so to spend and no c-cards again i really really appreciate all the help that i get from you guys on this site. Thank you

[BNaylor]

Regardless of the P1811 DTC are the 1-2, 2-3 and 3-4 upshifts still hard or harsh?

See link below which may be helpful and in there within the discussion you will see an inexpensive DIY fix that may work.

Click here

[tblake]

Bob, I was just going to mention your write up.

It should help out firm the shifts and reduce or eliminate slippage, correct?

(I wonder how many shops sell a "rebuild" when in all actuality the just do this procedure???)

[BNaylor]

Originally Posted by tblake

Bob, I was just going to mention your write up.

It should help out firm the shifts and reduce or eliminate slippage, correct?

A few disclaimers Tim. It depends on how bad the PCS is. Again nothing should be substituted for a proper repair job which is typically replacement of the PCS solenoid or sometimes a rebuild. However, not all hard/hard shift issues to include a P1811 DTC are the PCS and many people that replaced the PCS are getting re-occurring issues. There could be other issues such as worn out mechanical components like clutch packs, etc.

Basically the PCM looks at shift timing. Mainly the 1-2, 2-3 shifts. It looks for nothing greater than .65 seconds. If timing is seen above that depending on driving conditions it triggers a P1811 DTC. Due to the DTC setting the PCM then commands maximum line pressure and disables shift adapts. When this occurs you get the hard/harsh upshifts and many get a whining sound due to the high line pressure.

The fix which is adding an inexpensive shift kit to the 1-2, 2-3 accumulator improves the shifting and helps keep the shift timing to under .65 seconds which effectively inhibits the PCM from setting the P1811 DTC and then the hard/harsh shifts do not occur. The other advantage to this fix is any DIY capable person can perform it since you do a pan drop and only the accumulator is removed to apply the mod. Total cost is around $60 which includes the shift kt, screen filter and Dexron III or VI. The best results are obtained with the new Dexron VI since it is obviously a better ATF fluid. As you can see by the thread referenced the results are very impressive and has saved people a lot of money. Also, tranny operating temperatures drop or improve with Dex VI versus the old Dex III. Basically the mod out smarts the PCM module so you can get some more mileage out of the autotransaxle and save money. No guarantee it will work but for the cost and time it doesn't hurt to try it before having to spend the big bucks.

[tblake]

Would I benefit doing this mod before any hard/harsh shifts occur? Or should I just leave well enough alone?

[BNaylor]

Originally Posted by tblake

Would I benefit doing this mod before any hard/harsh shifts occur? Or should I just leave well enough alone?

The rule of thumb Tim is if it ain't broke then don't fix it but it is up to you.

But I've had the shift kit mod with Dex III in my GTP for about 4 years now but after the PCS was replaced. I recently converted both Regals I have with the shift kit mod and switched to Dex VI in those which indicates my confidence level. Plus I've done 3 other GM cars with the SII 3800 and 4T65E autotransaxle. No problems noted to date.