Problem downshifting to 3rd gear

My car is a 2004 GP Comp/G with 100K miles. When I give it a little gas to acclerate (in OD) the transmission acts like it shifts into neverland for a second and the engine will gain a few hunderd RPM and then finally it goes into 3rd gear. This morning I tried downshifting from 4th to 3rd with TapShift and the problem didnt seem as bad but it still felt like it went to neutral for just a second before it got 3rd gear. Once its in 3rd gear it doenst act like it slips, and it feels like it goes 2nd-3rd gear fine.

Am I kidding myself thinking a filter change may cure it?

Thanks!

Has the trans ever been serviced? If not a pan drop and filter change could bring it back to life...

Originally Posted by tms8582

Has the trans ever been serviced? If not a pan drop and filter change could bring it back to life...

I just bought the car 3 months ago after an idiot hit me and totaled my '02 Grand Prix, so I dont know what the service history is. The trans. fluid isnt bright red, but it isnt really brown and burnt either.

New fluid and filter can't hurt things. Its worth a try, and its pretty cheap to do.

Fluid and filter changes are always good.

But are you sure this is a new problem? In my experience it's always a split second between gears if you're doing a hard down shift. Once it latches in you're set for sound though. Just sayin.

I changed the fluid a couple days ago and it was more brown and burnt than what I could tell from the dipstick, so I am glad I did it. There was a little material on the magnet, but I thought overall the pan looked clean....which I took as a good sign.

Driving home this evening, I layed into it at 35-40MPH, 4th gear in Tapshift and the gear indicator changed to 3 by itself, and it did its shift to nowhere and then to 3rd routine. Tonight is the 1st time it did this. Does this help indicate where I need to look next, possibly a sticking solenoid or sticking valve in valve body?

Brandon:
It doesn't seem to matter if it is a hard downshift with my foot in it or just under light load. Looking back, it may not be a totally new problem, but it started acting differently and reving more between the 4-3 shift and that is when I got concerned. At first I thought it just didnt know if it wanted 2nd or 3rd for the downshift. Then last week it started to seem like it was going completely out of gear and slamming into 3rd when it does go into gear.

Hey man I have a 04 Comp G that has the same exact problem...all downshifts are normal except from 4th to 3rd....it takes a bit them slams into 3rd if you really punch it...still does it when I ease into it just can't tell as much because im not in it...I am going to do a fluid filter and shift kit today to see if that helps if I see positive results I will let you know!

Originally Posted by wa04compg

Hey man I have a 04 Comp G that has the same exact problem...all downshifts are normal except from 4th to 3rd....it takes a bit them slams into 3rd if you really punch it...still does it when I ease into it just can't tell as much because im not in it...I am going to do a fluid filter and shift kit today to see if that helps if I see positive results I will let you know!

I'll be curious to see if the shift kit helps. Ive put 400 miles on mine since the fluid and filter change and my car isnt acting any better. It actually did the same type of thing on a 2-1 downshift once(in the middle of an intersection). I have been babying the throttle and if I know a downshift is coming; I let off the gas, use tapshift to downshift, count to 3, get back on the gas and all is well. I plan on having a trans. pro look at it soon, but the guy I plan to have work on it is 90 miles from me and I havent had time to get it to him yet.

Pull a quart out and add a quart of Lucas stop slip. See if that helps.

Ok I did the fluid filter and shift kit last monday and have been driving it all...its better doesn't chill in neverland for as long but once it goes into 3rd it still bangs into gear just not as bad as it was...it used to do it in other gears in town like you where saying but the shiftkit seems to have fixed all that...overall my fluid was pretty dirty and had some material...I think ill try that lucas stop slip because im sure its the 3rd gear clutches dying...I don't use tapshift I just ease into it on downshifts then once its in gear I hammer down

you should have included lucas with your new fluid from the get-go. i do it with every fluid change. add 3 quarts fluid, lucas, then 4 quarts fluid and mines perfect on the dot each and every time.

Originally Posted by brandonl2000

you should have included lucas with your new fluid from the get-go. i do it with every fluid change. add 3 quarts fluid, lucas, then 4 quarts fluid and mines perfect on the dot each and every time.

I will deff have to do that then! Was hoping just a service would do the trick but obviously it didn't...Lucas here we come!

It sounds like you have a PCS issue. Commonly that bang shift from a pcs is helped by a shift kit.

The shift kit did help but didn't completely fix the issue...if it was a PCS issue wouldn't it throw a code...I am going to try the lucas and see if it helps...its just odd that it only does it on downshifts and not on upshifts. This is my first auto so I am slowly getting used to the nature of the beast

Oh..it's only downshifts. That's when you motor may rock in the bay. Have you checked your motor mounts?

I have not no guess I should look into it...im pretty sure its the tranny slipping though because the split second it takes to downshift there is no power to the wheels but then after it bangs or jerks into gear there is deff a s ton of power...its weird issue

For what its worth, I borrowed a scan tool to see if I could figure anything out. No slip codes were present. Its been a couple weeks since I did it, but I think it said the shift time was like .2 seconds. It had a readout for shift time error, but I dont remember it showing any. From what I could tell from the scanner, the computer thought it was going from 4th to 3rd like it was supposed to. BUT....I am a weekend mechanic, not a pro so I may have missed something or miss interpreted something.

It banged into 1st last night from about 10mph coast to light throttle application, just like it was on its way to 1st gear but hadnt got there yet when I gave it throttle. I will definately put a bottle of Lucas in it for $hits 'n grins to see if it does anything. I'm just baffled because upshifts, even at WOT seem crisp and it never misses a beat.

I'm not totally up on all my acronums...PCS?

PCS or EPC, both the same. Pressure control soleniod/Electronic Pressure Soleniod. It's what fluctuates our pressure to keep it from banging.

Originally Posted by DruMor

It banged into 1st last night from about 10mph coast to light throttle application, just like it was on its way to 1st gear but hadnt got there yet when I gave it throttle. I will definately put a bottle of Lucas in it for $hits 'n grins to see if it does anything. I'm just baffled because upshifts, even at WOT seem crisp and it never misses a beat.

hm this is awfully familiar
the exact words i used. slammed into first. never missed a beat WOT. mine was a dirty MAF first go round. then too active of an aeroforce gauge second go round.

try cleaning your MAF yet?
i know its an 04, but surely the same ordeal.

I saw my transmission friend last night and he told me he chased the same problem awhile back and he finally figured out what it was. I dont remember all the technical terms he used, but he said that a small valve in what he called a "channel plate" has a worn bore and allows fluid pressure to bypass it and not moved the valve when it is supposed to move. He said on the one he worked on before it was going to cost $800 for a special reamer to repair the bore, but a reman. "channel plate" was available for +/- $100 plus the old core.

The bad news.......he told me that if you have the transmission apart enough to fix this problem, that you rebuild the whole thing when you put it back together. So now I just have to decide if I want to cut loose of a couple grand to have him fix the thing.

So.......if this transmission is scattered out on a work bench being rebuilt, what would be recommended upgrades if I want to add, say 50-75HP sometime in the future. I have held off from modding because I didnt want to tear the tranny up, but if its out and apart anyway, I dont really mind spending some $$ to make the thing live under a little extra power, nothing wild as it is still my daily driver.

Thanks!!!