Surging Throttle after shift into Over-Drive Problem

E

EMF-Owner

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I am having a problem with my 2001 Oldsmobile Intrigue (6 Cylinder H 3.5L SFI) where the throttle surges after shifting into Overdrive. I do not think it is shifting in and out of Overdrive. It feels like the throttle is surging. I can see the tachometer rising and falling at the same time. It is a very smooth acceleration and deceleration like the throttle is being depressed and released. The surging gets less and less until it smooth’s out and then it is fine. I cannot say that it does it every time, but I think the problem is getting worse.

I thought that the Throttle Position Sensor was the problem, so I changed that last weekend. The problem is still there.

I have had some problems with the Pressure Control Solenoid on the transmission where it causes hard shifts, but usually if I shut the car off for 10 seconds and restart, the hard shifting goes away. Not sure if these problems could be related. They did not appear at the same time. I have had the periodic hard shifting problem since I bought the car. The surging throttle started in the last couple months.

Anyone have any ideas what may be causing the throttle to surge like this? I am sure it is some sensor someplace, but I am not sure which of the 1.4 million sensors it could be. Anyone else have a similar problem?

Thanks

John Daly (The E-M-F Owner)
 
Does it do it under load or all the time? I had a bad TPS and when I replaced it, the replacement was bad as well... so there's that...
 
It is happening at cruising speed. When it happens, if I accelerate a little, it stops. If I let up on the throttle, and re-accelerate, it may stop. That is why I thought TPS. I suppose the new one could be bad, but it is failing in the same exact way. Seems unlikely, but not impossible.
 
Additional Troubleshooting.....

Tonight instead of taking off by selecting "D" on the transmission, I used "3". I still experienced the same behavior.

Also, I seem to experience this more when the car is cold, instead of when It is warmed up. My drive is 52 miles on the way home from work. It happened at the beginning of the drive. I noticed when I got about 1/2 to 3/4 of the way home it was not happening anymore. I stopped and started several times with no surging.

I looked into the thread referenced in the last message. The Fuel Preassure regulator sounds interesting. I may look that up and pull the vacuum line and see if it will hold a vacuum.

Thanks for the help to this point. Please keep the ideas coming.

John Daly (the E-M-F Owner)
 
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