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Yet another hard shift question, lol

blackthunder

blackthunder

New member
A while ago my 04 grand prix GT started to hard shift in the city and it was hot out. Now I didn't have my reader with me (I do now) so I couldn't check to see if it threw a code or not.

now it hasn't happened again since and its been almost a month. A few things that I notice are the following.

- When downshifting from 3-->2-->1 (D to 3 is fine) it shifts hard, like bangs into gear. not so bad when I slow down so the RPM's dont go above 1500.
- When downshifting while passing it hard shifts sometimes. kinda rare in this case but happens a little bit.

From doing countless research on this forum, my guess would have to be the EPC solenoid or rather the Pressure Control Solenoid. Same thing. Or i install a shift kit.

now i understand that the shift kit is the cheaper way to go but im not sure if I want a shift kit in a bone stock GP, lol.

any insight would be greatly appreciated.

Thanks
 


The shift kit limits the movement of the shift accumulators. By doing this it makes the shift happen within the specified amount of time that the pcm expects. Without it the shift is slow and this causes the pcm to set a fault and use maximum line pressure for all shifts. Aka code 1811.

EPC or shift kit are the typical fixes.
 
if it was your car? what would you do?

financially speaking, I could get the intense shift kit and have money to buy other parts it needs. (i think my passenger axle is starting to go.lol) and other maintenance stuff like plugs and wires etc. also i think my intake gasket is starting to go (white smoke when engine is cold and under high RPM's)
 
If you want to break your neck at every shift get the intense. If you realize it's a Grand Prix and not a drag car and just want slightly harder shifts go with the trans go....plus it's half the price.
 


I too went with the Transgo 4T65-E Shift Kit. I also added Lubegard Red 60902 which is an ATF Supplement. The transmission has 218,000 kms on it shifts perfect every time (the problem I was having was not as severe but still there). I'm really happy with it.
 
thanks for the input guys! but still unsure of the issue when I manually downshift from 3-2 and 2-1 it slams into gear, is that still an ECS issue?
 
of course its slamming into gear when you manually down shift, your not supposed to do that. its a FWD car.

if you must slam it in to 1 st, give it gas as you do it, by goosing the gas the engines rpm's go up the gear catches at that higher rpm smoother, then let the gas go when you feel it catch.

you really asking for problems down shifting it into 2 or 1. its not needed.

if you want to stop faster get F body brakes on the front of your car, its worth every last dime, and slamming on the brakes wont hurt the tranny.
 
im not slamming it by downshifting, i could be at around 20km/h and when i downshift it slams. it shouldn't slam, at least i dont think it should lol. any other car ive driven never did that.
 
ever drive fwd before? they all slam when you drop a gear. the engine and tranny are trying to roll over in the engine bay when you down shift.

and once again there is no reason to be down shifting. stuffs gonna break.

20 km/h is what 12 mph in america? yeah, its gonna bang into gear at that speed.
 


Why the down shifting? It's an auotomatic.
Only time you really might need to downshift is to grab a lower gear to pass.
For driving around the city in London leave it in 3rd
 
With a shift kit, you will still get banging when downshifting (possibly worse). You working the tranny by manually shifting like you are and using your trans as your brakes instead of the pedal on the floor your trans temps will sky rocket. I have a TransGo shift kit in my trans and I downshift pulling a mountain because I am tired if it going back and forth into gears. I'd rather keep it in a lower gear so just cruise up. But with this said, if I downshift with my foot off the gas at a higher speed, it bangs.

I don't think a shift kit will help you. Drive your car normal and see if it stops... I don't hear any complaining of hard up shifts just manual downshifts, unless I misread something..
 
i think you guys misunderstood me, lol. I don't always manually downshift. almost never. I did it just to test it out after having the hard shifts thinking "i wonder if it would hard shift if I manually downshift" that sorta thing,lol.
 
in that case, that banging into gear when down shifting is 100% normal.

shift kit should clear up the hard up shifting. trans cooler cant hurt, and when you do the shift kit you'll be also doing the filter and 8 quarts of new fluid. maybe add 1 quart of trans stop slip as well, it cant hurt.
 


I've never been in an automatic that slammed into gears downshifting when I slowed to a stop... Sometimes if I am paying attention I can hear RPM change but that's it.

It sounds like his car is maxing downshift pressures (if that makes sense).
 
you got lost in the thread, he had a few harsh up shifts, then manually down shifted 2 then 1 and of course it banged into both gears.

he said he was just testing if it shifted ok manually, and got worried cause it slammed into gear when manually down shifting, like it will.
 
Just put the TransGo kit in. I would rate it as a stage 1 kit.

I have two years on mine and all is well. I downshift a lot. Mostly 4 to 3 and sometimes 3 to 2; it shifts normal. Now going 2 to 1 even at very slow speeds is uber clunky, so I stay clear of doing that.
 
If it were mine. I'd shift kit it. That takes me about an hour with the trans service in total. EPC is going to require the cradle to be lowered, the entire drivetrain then gets lowered and you are working with the trans at an angle not originally intended etc. It's not much fun to swap the EPC.
 
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