94 Bonneville stalls and jerks

[cheez_84]

I have been dealing with this for a year and it is getting worse. My Bonneville will suddenly stall when I am drving. I will be coming to a stop, my foot off the accelerator, my RPM's will fluxuate and then it will die. I have had my car hooked up to diagnostics and nothing comes up. Another problem is the jerking. It will begin to jerk when I am going down a hill. I have to take my foot off the accelerator or pound down on it to get it to stop the jerking. I really need help. Does this sound like a computer sensor problem or what. Two years ago my cam, crank, O2 sensors and my computer brain were all replaced when I bought the car-it had similar symptoms then.

[randman1]

The stalling problem when approching a stop sounds like an Idle Air Controller. The IAC is a motorized valve that opens and closes per the computers instructions to maintain a steady idle. More than likely, it is all gunked up and is slow to respond to the computer's instructions. A through cleaning is in order. On my 93, I removed the entire throttle body, removed the IAC, TPS and MAF, and cleanrd the heck out of the throttle body (which was completely filthy I must add). Use STP throttle bldy and intake cleaner and a small brush. I went through a whole can of the stuff. This should improve your idle.

You have me scratching my head on the jearking problem though. Is it only when you go down hill?

[GTP Dad]

I would also check to make sure the egr circuit is not plugged up. Simple to clean by removing the valve and cleaning it with carb. cleaner. If the passage leading into the manifold is blocked you will need to clean that as well. You can clean it the same way using a small brush and carb cleaner. You also didn't say if this was doing this after the torque convertor had been locked up. Sometimes this jerking can indicatate that the torque convertor solenoid is going bad and not unlocking the convertor causing stalling and jerking. Just a couple of thoughts.

[DMP43]

I had a similar prob with my '94 SLE. It would stall when I let off the throttle even at 70Mph!! Wouldn't downshift when I hit the pedal, the idle would go up to 2000 then back to normal. Screwy. I replaced plugs, wires to no avail. A chance encounter at a gas bar with the owner of a '92 pointed me to the fix. He suggested that the Throttle Position Sensor might be the culprit. When I got home I disconnected the sensor lead and went for a test spin. There was no difference in performance so the TPS could be the problem. I ordered one through an auto parts store and replaced it. Problem solved! It is like a new car. Kicks down when I hit the throttle, shifts cleanly and NO STALLING.

The part was about $90 Cdn and took about 2 hours to install as it is underneath the throttle body and adjacent to the intake manifold. Make sure the engine is COLD because you will burn yourself on the manifold. The Phillips screws holding the TPS could be seized so a shot of penetrating oil ahead might help. You may need to remove some of the intake plumbing or even the throttle body to get at the screws. Nonetheless, do the test first as the connector is easy to get at. If there is no change in performance then the TPS is the prob. Give it a burst...