1999 SC2 Shifting problem

[Bob Mayo]

This car has an automatic tranny. When the tranny shifts from 2nd to 3rd at 2800 RPM's there seems to be an extra shift a second later. If I count the shifts from standstill there are 4. That would make it a 5-speed and I don't think it is.

Also I noticed that when coming to a stop, the idle is too high. Once the car stops fully the idle drops to normal. I drove the car at 35 MPH and shifted into neutral. The RPM's are at 1500. If I keep rolling the RPM's stay at 1500 but as soon as I fully stop they drop to around 900.

The engine was replaced a couple months ago and I do not know if it could be a linkage adjustment. Since I do not drive this car much I do not know if these problems existed before the engine swap. Thanks.

[Ruley73]

Originally Posted by Bob Mayo

This car has an automatic tranny. When the tranny shifts from 2nd to 3rd at 2800 RPM's there seems to be an extra shift a second later. If I count the shifts from standstill there are 4. That would make it a 5-speed and I don't think it is.

Perhaps you are also noticing the torque converter lock-up after it shifts into 4th gear?

Originally Posted by Bob Mayo

Also I noticed that when coming to a stop, the idle is too high. Once the car stops fully the idle drops to normal. I drove the car at 35 MPH and shifted into neutral. The RPM's are at 1500. If I keep rolling the RPM's stay at 1500 but as soon as I fully stop they drop to around 900.

This is normal. The PCM is programmed to keep the engine idling higher when coasting. The same thing happens with cars with manual transmissions when you push in the clutch or put it in neutral and coast to a stop. This is supposed to decrease emissions from unburned fuel.

[Bob Mayo]

Originally Posted by Ruley73

Perhaps you are also noticing the torque converter lock-up after it shifts into 4th gear?
Thanks for the reply. Can you describe what Torque converter lock-up feels like?


This is normal. The PCM is programmed to keep the engine idling higher when coasting. The same thing happens with cars with manual transmissions when you push in the clutch or put it in neutral and coast to a stop. This is supposed to decrease emissions from unburned fuel.

When you say that this is normal do you mean for this car? My Villager does not do this. It seems dangerous to have the idle at 1500 RPM's when you are trying to stop the car.

[Ruley73]

Originally Posted by Bob Mayo

When you say that this is normal do you mean for this car? My Villager does not do this. It seems dangerous to have the idle at 1500 RPM's when you are trying to stop the car.

Normal for Saturns (S-series), but most other cars behave the same way. I understand your point about it being dangerous, but keep in mind that when you hit the brakes your engine RPM drops because the brake booster pulls a modest amount of vacuum from the engine (which is yet another reason the engine RPM needs to be above idle when coasting). Also, when the car is in neutral the higher engine RPM doesn't hinder the car's stopping ability because no power is being transferred to the driveaxles.

[Bob Mayo]

Originally Posted by Ruley73

Normal for Saturns (S-series), but most other cars behave the same way. I understand your point about it being dangerous, but keep in mind that when you hit the brakes your engine RPM drops because the brake booster pulls a modest amount of vacuum from the engine (which is yet another reason the engine RPM needs to be above idle when coasting). Also, when the car is in neutral the higher engine RPM doesn't hinder the car's stopping ability because no power is being transferred to the driveaxles.

Thanks for your response. I tried coasting in neutral just to see the RPM's without the transmission engaged. I'm going to try a fluid and filter change to see it it helps the shifting problem.

[RC1488]

Replace your ECTS and Clean your throttle body along with the fluid/filter change