3800 Engine Oscillation

My new to my wife 1992 Park ave, seems to have intermittant problem.
The engine will begin oscillating moderate to rapid when climbing hills.

Problem occur in lockup at 60 mph. Axle ration is 2.83, Rpm is 1600. When applying power to climb the hill, as the engine really start to pull hard, but before TCC disengages.

Replaced wire, and plugs, oscillation began at a later, or higher power setting. Replaced two coil modules, no change, rotated third coil with two other oem coils, no change.

Any suggestions

Mark

Check fuel pressure and if you have access to a scan tool also check the O2 sensor operation.

Check fuel pressure and if you have access to a scan tool also check the O2 sensor operation.

Thanks. I will check these. I just found out that the car is a 92, but the engine appears to be a later year. A 92 in the salvage yard had the upper intake as aluminum, my car is plastic. The engine was replace by the PO.

Mark

I borrowed a Scan tool from a friend at church.

After a couple of hours, I noticed the engine knocking on load, but the o2 voltage and A/f mixture said above .7, with a crossover of 0-36, indicating a mostly above stoichmetric. As quick check I disconnected the O2 sensor cable, and the pinging stopped immediatly

What's wierd, is that even though the check engine light illuminated, the scan tool indicated that it was still getting data from the O2 sensor! This has me baffled. ON my other car, VW Vanagon, the O2 senor wire to the computer is famous for shorting out. So I guess I investigate that.

After I got home just sitting in the driveway I began reading about the scan tool and such and so I began testing the Throttle position sensor, w/key on, but no engine runninin. I tried to make the voltage rise by slowly depress the accelerator pedal. At 65% the voltage seemed to jump a bit after a rather long movement on the pedal with no response.

I drove the car, repeating this 65% conditon and the car jerked each time-- So That's definately one part of my ocillation problem

I'll Check the O2 sensor wire to computer today.

I also noticed that while the Knock sensor worked, but I could hear knock, with no knock sensor acknowledgment. So Lastly I may just replace this thing because it's lost it's sensitivty. After the TPS and O2, and a computer reset. If it still is suspect.

My last question is that the timing seemed to be only at 30 degrees or so on 87 octane. Is this a normal max timeing? or will it be higher after I fix the other problems.

Mark, not really a student, more of a self-taught mechanic. Just the only name I could think of to get past the moniker thing on setup.

Mark

So, I replaced the both the O2 sensor, and the Throttle postition sensor- solving the knock and throttle response.

Now the engine ocillatates or surges anytime I accelerate. I begin paying attention to the transmission TCC slip RPm, Book says 10 or less is ok. Mine is plus 150-200 when I accelerate.

So the problem is a slipping torque convertor lockup.