Starting just a couple of days ago I noticed it was occasionally shifting abruptly. Then today I was trying to back up and experienced what I discovered here is called "reverse slam". Had just driven 60-70mph for the past 20mins. Figured I needed to check the fluild level when I could get to level ground but forgot until I had driven another 40mins at speed. I stopped to check the fluid and that's when I discovered that reverse didn't slam anymore because there was no reverse at all. The fluid was right in the middle of hatched area on the stick and looked and smelled just fine. From that point on until I got it home again (another hour of driving) the transmission would seem to skip 2nd gear and go straight for 3rd. The SES light was on but it has been on and off almost since I bought the car. Every car I own likes to flash that light so I hardly pay attention to it anymore. My thinking was always: oil good, temp good, volts good, I'm not worried about some sensor complaining it's not going to pass a smog test. Well maybe I should pay more attention to that "idiot light" since it may have been trying to warn me about this very situation that has developed. I've read about the so called "reverse slam cure" and will give it a shot in the morning since it's so easy and inexpensive. Also, having had a chance for the tranny to cool down might make a difference. Meanwhile, I'll see if I can dig up my code scanner and check those codes. I'll post back what I find and go forward from there.

 

Sounds a little like a valvebody issue... Unfortunately, my time with the S series was brief enough that I don't remember much else... Codes read from the PCM would help greatly...

 

they are likely incorrect gear ratio codes (new codes) and if the SES light is flashing it means an active misfire is occurring.

Likely valvebody

 

Managed to get out this morning before the rain hit and did a fluid and filter change on the tranny. Added some Lucas trans additive and performed the "reverse slam cure". I kind of have a very slippy reverse now if I tach it around 4k. Better than before but not by much. I haven't been able to find my code reader yet, must be in a "safe place". The old fluid still looked remarkably good but in the daylight I did notice just a touch of discoloration but still no burnt odor. The filter didn't look bad inside and there was only the normal amount of sludge on the magnet, no shavings or sparklies. I'm going to double check that the shaft nut hasn't worked loose when the rain stops (might be awhile).
When I was researching this problem I was encouraged by the fact that this is basically a manual tranny with auto shifting. It also seems I should be able to make the most common repairs without even pulling the tranny since it's most likely the valve body and or the shaft nut which are accessible from above and the side.

 

P0133
HO2S Slow Response Bank 1 Sensor 1

P0113
Intake Air Temperature Circuit High Input

P0341
Camshaft Position Sensor 'A' Circuit Range/Performance

P0442
Evaporative Emission Control System Leak Detected Small Leak

P0731
Gear 1 Incorrect Ratio

P0732
Gear 2 Incorrect Ratio

Found this site quite useful: OBD2-OBDII Engine Light Trouble Codes Definitions, Description and Repair Information | Engine-Codes.com

I expected the last two codes given the tranny problems but the others were a revelation. I had been experiencing some intermittent stalling and power problems but not frequent enough that I was worried about it. Now it seems I have some clues to what was causing it. I went ahead and cleared all the codes and none recurred while sitting in the driveway at idle fully warmed up. Ran through the gears, gave it some revs and still no codes. I'll watch this situation later when I actually put some more miles on it and if there are any new codes I'll post them here.

 

Based on mileage, P0133 , replace front 02 sensor

P0113 IAT --clean contacts on connector. Then measure V across the connectors.
If you measure 5V, supply to the sensor is good and sensor is likely faulty.
If you measure 0 V, the two wires are shorted together somewhere betw the sensor and he PCM. Actually measure each pin to ground to ensure they are both at 5 V -- which is wrong

P0341 There is no cam sensor on s cars. This code means the ignition system is not happy.
---Run stock copper plugs, nothing fancy
--when was last tuneup?
Etc

P0442 Evaporative Emission Control System Leak Detected Small Leak
this is no fun and info is all over the net, so have at it.
Could be as simple as an evap or purge solenoid, or much nastier to find like a mircropinhole on the filler neck of the tank.

 

You have a temperature sensor on the transmission. It's right under the ECTS for the engine. Perhaps that is bad. I had to replace the valve body in my SC in order to eliminate that "reverse slam", but that cured mine. The hardest part of it was getting the damned ABS assembly out of the way so I could remove the pan from the transmission.

 

Checked for codes today after driving into town and back a couple of times (20min each way). Tranny no better than yesterday as expected but did get the SES light on again. Checked and it's just one code: P0732. Still haven't checked the shaft nut but it's looking like that's a strong possibility since it's actually trying to go for second but not really getting there, just going into 3rd when it's time. If only the rain would stop.

Derf: thanks for the advice on the PO113, when the weather clears I'll be checking that for sure. As for the last tune up? Previous owner maybe? The car has really been running quite well so I haven't felt pressured to make any changes there. The P0442 could just be from forgetting to put the gas cap back on one time. As long as I don't smell or see gas leaking I'm not going to put too high a priority on that.

Rube: Although I doubt that the temp sensor is the sole cause it's worth checking out. I'll have to find the test procedure.

My biggest priorities on this car before the tranny started acting up was trying to get some fresh tires and an alignment since they were all down to the wear bars (the front were even showing steel). The rear needed only a slight alignment adjustment but the front was fine. Turns out my twisty road home, quick driving and cheap tires was the cause for the front ones going bad after just 20k miles. So that's why I hadn't been doing much about the running issues since they only happened rarely and only for a minute or two.

 

P0732---no 2nd gear. That explains you last drive behavior and code.
Note: 2nd gear and reverse share the same solenoid in the valve body, as well as the same clutch pack and clutch piston inside the tranny.
The usual suspects are
------Loose input shaft nut--check first
------bad solenoid for 2nd gear/Reverse
------Leaking 2md gear clutch piston

People rebuild these Saturn valve bodies all the time. Check Ebay.

P0442---EVAP (small leak) --- embarrassed I forgot to list this

P0133---The 02 sensor code will reset in about 25 50 mi once the monitors are completely redone after the code clearing. Emissions usually takes the longest to recover.

If replacing front O2, use the Denso sensor specified but find it yourself on Rockauto via GM part num crossref. Costs 2x as much at the gm dealer .....

Surprised the 0341 hasn't come back....

input shaft nut check first.

the 2nd/R combination could just be a solenoid -- but it could also be the leaking 2nd gear clutch piston.

I am by far NOT a tranny expert, so don't RUN with my advice..... but Alpha Centauri is.

Alpha? You out there?

(also, please tell me what parts of my guestimation are incorrect)

 

Derf, I'm fairly certain the input shaft nut has worked loose. I don't have a sheltered area to work so I need to wait for better weather to check that. Not much worse than trying to work in muddy gravel in the rain.

I wonder though, could something else have triggered the input shaft nut working loose. On my Metro there is a similar condition to the reverse slam that if allowed to happen basically more than once will definitely loosen the shaft nut.