Hard Shifts

seriously, it hasn't happened in over 2 weeks after I tied that dipstick down

My car seems to shift crappy between gears 3 & 4. Are these codes anything I should get fixed

Calibration changes to improve harsh 3-4 shifts

Allows for crank angle relearn and VSS malf code to set. Also corrects eroded spark plug electrodes.

Control module calibration

Where are these codes coming from?

Yesterday I went to town and the fiance, I, and the kid were all gonna hop in the Riv and take it up to my sisters which is about an hour away. Well on the way to town to get some gas it began shifting VERY firm. Hard enough that it was beyond firm shifting. So I pulled off and shut it off and started it back up and it drove completely normal.

We ended up taking the Jeep GC because of it and it hasn't done it since. Was it just some electrical or vaccum fluke? Car has 186k on it and it shifts like a dream but I have no idea when the fluid was last changed or if it has been. I may do a drain/refill soon.

What year is your Riv again?

I would check the vacuum lines for cracks. Mine was shifting hard once, and that was the problem.

It's a 97

I'll do that when the rain quits and it warms up. Hopefully it doesn't happy again in the next day or two

When it rains it pours!

Started the car up this morning and took off and noticed it didn't immediately shift. 1-2 was pretty delayed. After that the shifts were not delayed but 1-2 is shifting pretty hard. Not hard enough to break anything, but it's VERY firm. Fluid looks/smells good and is full.

Any danger in driving it like this for a while? My guess is a failing solenoid but I still need to check the vac line. Looking for some insight.

EDIT: Didn't see any vac lines going to the tranny.

I believe on the 97 the trans is electronicaly controlled, not by vacuum. Wish I could be more helpful cause while it MIGHT not break anything hard shifting will hasten the wear process on all driveline components and your trans mount. Hopefully one of our more knowledgeable board members can chime in and help you out.

Derek wrote:

I believe on the 97 the trans is electronicaly controlled, not by vacuum. Wish I could be more helpful cause while it MIGHT not break anything hard shifting will hasten the wear process on all driveline components and your trans mount. Hopefully one of our more knowledgeable board members can chime in and help you out.

From the searching I've done, you're right. It doesn't feel hard enough to break anything but if it gets any harder I would be much more concerned.

This only happens on the 1-2 shift?

Abaddon wrote:

This only happens on the 1-2 shift?

Correct. All other gears are smooth as butter. No downshifting issues either.

Eh, could be a sticking 1-2 Shift Solenoid.
I'd wait and see if it gets worse, or you adopt some more (different) symptoms.
If the 1-2 Solenoid fa!ls, the car will start out in 2nd gear, and would shift horribly. The PCM enables max line pressure and turns off the Shift Adapts when a shift solenoid fails, so you'll know when it goes (not to mention the SES light....P0753). I'm no trans tech, but I had to replace one this week at work

Abaddon wrote:

Eh, could be a sticking 1-2 Shift Solenoid.
I'd wait and see if it gets worse, or you adopt some more (different) symptoms.
If the 1-2 Solenoid fa!ls, the car will start out in 2nd gear, and would shift horribly. The PCM enables max line pressure and turns off the Shift Adapts when a shift solenoid fails, so you'll know when it goes (not to mention the SES light....P0753). I'm no trans tech, but I had to replace one this week at work

A couple months ago the car shifted VERY hard into all gears. Turned the car off and back on and it never did it again. Now it's shifting much firmer than normal, but not hard enough to damage anything IMO. Shifts are no harder than a basic shift kid would provide.

As far as replacing one, do you just lower the cradle on the trans side to get the cover off?

Well, now that I look at it (for the Riv), the 1-2 solenoid also controls the 3-4 shift. Different solenoid for 2-3. I would imagine 3-4 would be unpleasant also.....

As for the installation, see this link
I had to change my TCC Solenoid. It got to the point that it was causing take-off "judders" and delayed 2-3 shifts.
In the lower picture, the 1-2 shift solenoid is the very top solenoid on the left.

First thing I would do is scan to monitor shift pressures at different shift points. Sometimes the PCM can command 96 psi at all times. If it detects a problem, it can change to a different shift line. This will cause a hard shift. Also, I've had hard shifts with a vacuum leak - even though the transmission is electronically controlled, vacuum did affect the shifts.

Hmmm... no issue at all with 2-3 or 3-4.

AA, what do you recommend using to monitor shift points?

If you know someone with an OBD II scan tool, hook up and drive while monitoring trans fluid pressure parameter. It should change as you add throttle according to the pressure lines in the PCM, but if it's locked at 96 PSI all the time, it means the PCM is ignoring the lines, indicating some problem the PCM is aware of. If the pressure changes normally and no codes are thrown, you can rule out the PCM adjusting your shift pressures.

I use AutoTap w/GM enhanced parameters, which sells for $250. Unless you plan to do your own diagnostic/tuning work from now on, it may not make sense to buy, but it is an option if you have a laptop and want to see what's going on in your car's brain. You can also use the software to scan any car '96-up, and you'll have special parameters for any GM '96-up.

Don't know anyone with a scanner off the top of my head.

May not be related but I noticed my cruise control was not working the other day.

AA wrote:

Sometimes the PCM can command 96 psi at all times.

Just to clarify, I'm pretty sure that's 96% of available pressure. I connected a pressure gauge to the trans and 96 on the scanner was really more like 220 PSI.

DHP Powertuner and Autotap scanners both show units listed as PSI, so I believe it is correct:





I think this is a base figure used by GM, that can be multiplied by another parameter called Commanded PCS Amps. The PCS Amps value can range from 0-1, with 0 giving the base pressure value, and higher values commanding higher pressures, possibly up to the 220 PSI you measured.

I agree, I first noticed it in autotap, and dhp and hpt have consistently shown the same thing. But that command does not reflect what a pressure gauge shows. The gauge does move respectively to the "psi" indicator, but is not 0-96 psi, rather 0-250psi or so. What made me suspicious of the readout in the first place was that I couldnt set the shift pressure above 100. So I wanted to see what the actual pressure was. There is a 1/8 Npt hole on top of the trans near the crossover pipe, trans vent. Take the plug out and thread in a gauge fitting if you want to see for yourself.

Took the car this morning and it was still shifting pretty firm. Shut it off and came back out and now it's back to shifting smooth as ever.

If it is a sticky solenoid, is this a sign it's going to completely go out soon or just that this could keep happening?

manofmany wrote:

Took the car this morning and it was still shifting pretty firm. Shut it off and came back out and now it's back to shifting smooth as ever.

If it is a sticky solenoid, is this a sign it's going to completely go out soon or just that this could keep happening

That's kinda why I said to wait for "different" symptoms. The TCC Solenoid on this trans has a habit of getting clogged/sticky. It causes a couple different issues. I wouldn't worry about it until then.......you may spend too much time trying to find a ghost.

Also, I was thinking about it. A skewed MAF sensor can cause less then desired shifting performance too. But, if it only happens from 1-2, then the MAF wouldn't make any sense. Again, I'd wait.

I would say get your trans fluid and filter changed. Sometimes it's just dirt/crap that got dislodged that makes the solenoid sticky. A fluid change should help.

My preference is to see trans fluid and filter changed once a year and never flushing.