[Solskillz]

So I have an automatic transmission and I've been glancing at a few threads regarding this issue and I don't really know where to start.

Everytime I slow down and my speedometer is at around 20mph, it suddenly downshifts really rough and my car jolts and pulls me back very abruptly. It was a very scary moment since I had no idea what was going on.

Then it started getting predictable like everytime my vehicle went down to 20mph, it would do the same thing each and everytime.

I originally thought it was my brakes but even when I didn't use the brakes, and just let it slow down to 20mph, it would do the same thing. Then at 5mph, it does a very minor tug....

I was wondering how many people have dealt with this issue and whether there was ever a solution or what should I tell the mechanic when I bring the car to the shop? After reading some of the threads, I noticed some of you had certain sensors replaced that solved the issue or at least temporarily solved the issue...

Then I read something about the auto trans going into "protective mode" for any number of sensor issues...

Could these be what I'm going through? Is anyone familiar with what I'm going through? It's scary since I drive the freeway everyday to work and I would hate for this to happen when it rains

Any honest help or advice would help and thank you.

 

[rob the elder]

The first thing to check is your cam position servos and position sensers. They are described with pictures in the transmission suckage thread and others. They are easily changed out by anyone willing to turn a wrench. If one has failed or is sticking it will cause your symptoms. The other thing to check is your oil level. If it's low, it can cause a lack of pressure at the servo.

 

[mcpigm01]

I don't know if the CEL is on or not but my company car is a 2008 Chevy impala ltz and it started having these issues around 140k miles while I was out of town on business so I took it to a local shop myself t ensure I wouldn't get stranded on the drive back. The mechanic pulled the code on it and said that it had something to do with a long shift or something and that the computer could no longer adapt to the shifting habits of the transmission. He overfilled the transmission by one quart and cleared the code and told me to drive it and it should be fine. 20k miles later it is doing just fine. I don't know if it's a similar issue, with the pontiac being a GM but, that's just what it reminded me of.

 

[DaveOC]

http://www.solsticeforum.com/forum/f12/auto-transmission-suckage-65252/

 

[MidniteBlues]

Oh yea, I had the absolutely same problem with my sky NA automatic, the fix for the problem ended up being this >>>12646783 VALVE (Adviser called it ("Actuator, Solenoid Control")

Here is my old thread from the skyforum...check out post #23..:thumbs:
Door Chimes Going Off & other Issues - Page 2 - Saturn Sky Forums: Saturn Sky Forum

Good luck let us know if it was the same thing with your sol..:thumbs:

 

[[email protected]]

So I have an automatic transmission and I've been glancing at a few threads regarding this issue and I don't really know where to start.

Everytime I slow down and my speedometer is at around 20mph, it suddenly downshifts really rough and my car jolts and pulls me back very abruptly. It was a very scary moment since I had no idea what was going on.

Then it started getting predictable like everytime my vehicle went down to 20mph, it would do the same thing each and everytime.

I originally thought it was my brakes but even when I didn't use the brakes, and just let it slow down to 20mph, it would do the same thing. Then at 5mph, it does a very minor tug....

I was wondering how many people have dealt with this issue and whether there was ever a solution or what should I tell the mechanic when I bring the car to the shop? After reading some of the threads, I noticed some of you had certain sensors replaced that solved the issue or at least temporarily solved the issue...

Then I read something about the auto trans going into "protective mode" for any number of sensor issues...

Could these be what I'm going through? Is anyone familiar with what I'm going through? It's scary since I drive the freeway everyday to work and I would hate for this to happen when it rains

Any honest help or advice would help and thank you.

A couple things I would check -

Clean your MAF sensor - they tend to get dirty on these cars. The MAF sensor tells the ECM how much air is coming into the engine and is also used by the TCM for shifting. If you have not cleaned it lately, go to any auto parts stores and buy some "MAF cleaner". This can also cause the mis-fires that you reported also.

Do you have an aftermarket intake? - If you have an aftermarket intake (other than GMPP or K&N) it can cause issues with shifting on the automatic cars. Especially when the seasons change, and especially if the MAF is dirty.

You can check the level in the automatic transmission, but it is kinda a pain. You have to have the car on a lift, remove the belly pan under the transmission. There is a fill plug that is almost right against the body of the car that you remove. If the fluid is up to the level of the plug you are good to go. That is also how you refill the transmission. Not easy, but it can be done.

Hope that helps.
Dave

 

[24222]

When my throttle position sensor went in my truck it had very similar reaction to yours but I'm not sure if these cars are set up like that but any-ways it something to consider.

 

[rob the elder]

I have been considering your first message again. Most people with the transmission hard downshift have it only occasionally, not every time they slow down.

The fact that yours is doing it every time suggests a hard failure or as Dave suggests a MAF issue.

In looking at this problem I was told that the ECM can work around a lot of issues and continue to operate the engine. But if the TCM to ECM data exchange is "bad" then the TCM will shift hard every time.

Try clearing all the codes and rebooting the car. Pull the battery terminal for 5 minutes, then reboot the car, start it up and test to see if the hard shift still happens in every instance.

If it does, then do the simple things first. Clean the MAF and check for any loose wires, grounding problems with the engine ground, check the MAF sensor wiring and plugs. If you find nothing obvious I would then go to the cam position servos and the cam position sensors. Pull them and inspect them to verify that they are looking good. Verify the oil fill level. Low oil has been known to cause issues with the position servos as they are driven by oil pressure. Changing out these servos/sensors is easy and relatively inexpensive to do.

If you are sure that there are no obvious problems with the MAF, the oil level is good, and the servos and sensors are known good, then go to the transmission and verify the oil level.

Good luck.

Know that you are not alone. :devil:

 

[chickenwire]

I'm telling ya, I'm designing and building "ctl-alt-del" buttons for the steering wheel so you can reboot at will.