On an older GM engine...a 1998 V6 3800 I been reading that it is common for the PCS to go bad which causes the transmission to hard shift. I only notice this when going from 1st into 2nd gear and I wouldnt describe it as a hard shif per say...but I feel a faint thump as it changes. My question is, is this hurting anything to not replace the PCS if this is the cause of this symptom? Is it causing damage to the transmission?
1998 GM V6 3800 Ii (Pressure Contol Solenoid)
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If its the 4t65e then there is a shift kit made by transgo. Some people have had success with that. Also what fluid are you running? My advice is to change the fluid and filter. Most people recommend Dex 6. If a fluid change does not help then its most likely the pcs is bad. The shift kit is supposed to trick the computer into thinking its shifting properly. I conquered the hard shift with a few pan drops and the addition of lubegard red.
Harsh shifts are the #1 contributor to the splines stripping off the 4th/OD Gear Hub, GM hardened the splines on later units & updated the service parts for your unit. I'm guessing you don't know if your unit has been rebuilt or had the updated service part installed?
To properly diagnose the PCS Solenoid aka Force Motor.......You need to measure the ACTUAL amperage applied to the solenoid/motor with a DVOM & compare it to ACTUAL pressure readings taken with a pressure gauge using a Pressure vs Amperage chart that I will gladly post if you decide to tackle this.
Installing a new Delco PCS solenoid along with a Trans-go shift kit will fix harsh shift complaints more often than not.
To properly diagnose the PCS Solenoid aka Force Motor.......You need to measure the ACTUAL amperage applied to the solenoid/motor with a DVOM & compare it to ACTUAL pressure readings taken with a pressure gauge using a Pressure vs Amperage chart that I will gladly post if you decide to tackle this.
Installing a new Delco PCS solenoid along with a Trans-go shift kit will fix harsh shift complaints more often than not.
Thank you for that info. So if GM built that transmission with reinforced splines then it's not hurting anything until I fix it? Also...just to be clear. This shift I feel can only be felt. You cant hear anything bang or clunk. It's just a real fast lurch and so slight that most ppl would notice unless they were driving it and I pointed it out. But all I know is that it's not a seamless shift...you just feel this slight pulse as it shifts
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Originally Posted by Mark72
Thank you for that info. So if GM built that transmission with reinforced splines then it's not hurting anything until I fix it?
I forget the actual date GM started using the updated part on new PLANT built units, I think it was late 2003.
Service part & SRTA rebuilt unit updates would of coarse come later on.......
Thank you for that info. So if GM built that transmission with reinforced splines then it's not hurting anything until I fix it?
I forget the actual date GM started using the updated part on new PLANT built units, I think it was late 2003.
Service part & SRTA rebuilt unit updates would of coarse come later on.......
I carried this down from my previous reply..
Also...just to be clear. This shift I feel can only be felt. You cant hear anything bang or clunk. It's just a real fast lurch and so slight that most ppl would notice unless they were driving it and I pointed it out. But all I know is that it's not a seamless shift...you just feel this slight pulse as it shifts
Also...just to be clear. This shift I feel can only be felt. You cant hear anything bang or clunk. It's just a real fast lurch and so slight that most ppl would notice unless they were driving it and I pointed it out. But all I know is that it's not a seamless shift...you just feel this slight pulse as it shifts
Shift feel is a tough one to convey over the internet, But a "Bump" at the end of a shift could very well be an "Accumulation" issue from a broken Accumulator Spring &/or leaky accumulator pressure at a piston.
Worn frictions can also cause this phenomenon as well as burnt/depleted/sheared ATF.
Worn frictions can also cause this phenomenon as well as burnt/depleted/sheared ATF.
I would not rule out a worn or cracked engine mount on these specific engines, particularly if the car is SC. Shifts can accentuate this "feeling" when a mount is bad.
I've considered that it could be a mount also. But I only ever notice this issue after the car is warmed up. Wouldnt a bad mount do this regardless of operating temp? Also as I mentioned...what I'm feeling when it shifts is so slight. It's more of a "bump" sort of feel. I hear no clashing of steel or anything. In my 2017 Pacifica before I had the computer reset it would hard shift...now that sound like and hammer hitting steel.
There are videos on You Tube showing how to check for a bad mount, you'll need a helper to perform this test. I think those mounts are hydraulic.
Had mounts checked. They are fine. Everywhere I read talks about a Pressure Control Solenoid exhibiting the same exact symptoms I'm having. I feel a thump or lurch when it shuts gears after the car is warmed up. My main question is...until I do fix it will this split second delayed shift cause any damage? AMD also where is it located,? I cant find anywhere online about this car to see if it's an easy thing to get to.
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Originally Posted by Mark72
Had mounts checked. They are fine. Everywhere I read talks about a Pressure Control Solenoid exhibiting the same exact symptoms I'm having. I feel a thump or lurch when it shuts gears after the car is warmed up. My main question is...until I do fix it will this split second delayed shift cause any damage? AMD also where is it located,? I cant find anywhere online about this car to see if it's an easy thing to get to.
I believe its located by removing the side cover. Not exactly the easiest job. The shift kit can be installed by taking off the pan. Except the 4th gear. If you're taking off the side cover might as well install the whole kit.
Had mounts checked. They are fine. Everywhere I read talks about a Pressure Control Solenoid exhibiting the same exact symptoms I'm having. I feel a thump or lurch when it shuts gears after the car is warmed up. My main question is...until I do fix it will this split second delayed shift cause any damage? AMD also where is it located,? I cant find anywhere online about this car to see if it's an easy thing to get to.
I believe its located by removing the side cover. Not exactly the easiest job. The shift kit can be installed by taking off the pan. Except the 4th gear. If you're taking off the side cover might as well install the whole kit.
There's a few ways to tell if damage is occurring. Is the fluid black or burnt smelling? Is it gritty feeling in between finger and thumb? On that unit overdrive is usually the first to go, but clanking sounds or delayed gear engagement are also signs of damage. That's about it other than disassembly of the unit.
Well...there is a new verdict out on this. Dont ask how...maybe sheer luck. But I put a new MAF sensor on it and it shifts smooth now. I had read that those when failing cal also cause erratic and rough shifting. Are any of you familiar or have experienced failing MAF sensors? Makes me wonder how many of these GM engines that have known trans issues were only due to a MAF and was overlooked just because it never threw a code.
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Congrats on finding the issue! MAF values are used to calculate Engine Load. If the MAF is over-estimating air-flow.....Harsh shifts can result!
But this is one of the more rare modes of MAF failures....They typically under-estimate air-flow resulting in softer shifts.
But this is one of the more rare modes of MAF failures....They typically under-estimate air-flow resulting in softer shifts.
Ok..so what exactly is a hard shif vs a soft shift? I was under the impression that any abnormal shift is a hard shift. What I noticed was a lurch or slight bump as it shifted. Nothing banged or clunked. And I could hear anything...you would just feel it as it shifted. So is that actually a "soft shift"?
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