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SuperKONR 11-02-2019 06:30 PM

SL1 Automatic Issues
 
The transmission in my 02 SL1 is sometimes wanting to randomly jump into a really low gear even though I'm barely touching the throttle. It seems to only happen when it's fully warm, I don't have problems when the temp gauge is at 1/4 or below. If the heater is on it never gets past that point so I can drive it around forever with no issues. Another thing that happens when it warms up to that point is at idle in gear, the engine will slowly surge between 5-700 rpm, not sure if it's related if it is an electrical issue.
The car was wrecked in the front and whoever put it back together left half the bolts loose or missing, so I previously reconnected a ground strap to the computer that's next to the battery. Apparently that wasn't the whole issue. I've replaced the coolant temp sender.
Should I look at the TPS? Not sure how to check it if it's only malfunctioning intermittently while hot. Anything else I should be looking at? It's had an IAT sensor code for awhile, I thought it was only throwing the code because it was unplugged at one point but could that sensor be causing issues?

toggenburg 11-03-2019 03:27 PM

Re: SL1 Automatic Issues
 
You said,
"I don't have problems when the temp gauge is at 1/4 or below. If the heater is on it never gets past that point so I can drive it around forever with no issues".

Please clarify 1 thing.
After you replaced the ECTS (verifying the connector was clean, and any wiring splice is soldered and shrink taped), so does the engine temp EVER go above 1/4 if the heat is OFF?

SuperKONR 11-03-2019 09:52 PM

Re: SL1 Automatic Issues
 
Yes if the heater isn't on full blast it warms up to just under half on the gauge. So maybe a sensor on the engine is just intermittent when normally heat soaked? Or maybe it's just a coincidence that it does it when warm, is there a downshift solenoid in the valve body that could be sticking? Any ideas??

fetchitfido 11-03-2019 09:59 PM

Re: SL1 Automatic Issues
 
Unless it's fairly cold out, under 50f, the heater shouldn't bother even the SOHC that much. Kinda sounds like your thermostat is stuck open but the owners manual does point out it sucks to have a SOHC in the cold because it can't keep both you and the engine warm.

The automatics are pretty sensitive to fluid viscosity and voltage, if either isn't right you'll have issue's and if the fluid's been bad for a while it can lead to more annoying issue's with the valve body.

SuperKONR 11-03-2019 10:09 PM

Re: SL1 Automatic Issues
 
ya it's been about 8 degrees out here in the morning, it's not gonna warm up all the way.
I guess I'm looking at TPS then valve body and the voltage things are getting. I just changed the ATF with some Castrol conventional, old fluid looked good.

gveinot 11-04-2019 07:24 PM

Re: SL1 Automatic Issues
 
make sure your alternator output is between 13.8 - 14.6 volts while the engine is running. The Saturn Automatic and PCM needs those voltages to run correctly. The solenoids in the valve body that select the gears are all voltage controlled, check the wires from the top of the transaxle to the PCM and make sure none of them are nicked and shorting out with each other or the chassis.

SuperKONR 11-04-2019 09:14 PM

Re: SL1 Automatic Issues
 
[QUOTE=gveinot;2309592]make sure your alternator output is between 13.8 - 14.6 volts while the engine is running. The Saturn Automatic and PCM needs those voltages to run correctly. The solenoids in the valve body that select the gears are all voltage controlled, check the wires from the top of the transaxle to the PCM and make sure none of them are nicked and shorting out with each other or the chassis.[/QUOTE]

Awesome I will check that out. Thanks!

SuperKONR 11-06-2019 12:35 AM

Re: SL1 Automatic Issues
 
Just some progress to report... Battery voltage is 14.6 running. Voltage through the ground at the under-hood computer is 14.2. So it seems to still be getting enough voltage. I swapped the TPS with one from the junkyard and the trans does the same thing, so at this point I'm going to get a valve body for the thing and see what happens.
I've been driving it all over today and it shifts butter smooth. No more banging into 2nd or 4th. Not sure if it's just finally clearing itself out or if it's because it's warmed up, we shall see in the morning when it's cold. It's still just occasionally randomly downshifting into (2nd?) and throwing a P0733 code. I think what's happening is that the computer thinks it's in 3rd, but it shifts into 2nd and therefore thinks it's slipping? Trans doesn't feel like it slips at all.
I'm going to see what the valve body solenoids are ohming at, I will likely end up reconditioning a used valve body and swapping it in.


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