Car is bucking

Welcome to 2CarPros.

If the mounts are bad, it won't cause the engine to buck. You may hear it when you place it in gear. What I need you to do is check for diagnostic trouble codes. This vehicle has an OBD1 system and you don't need a scanner to check. All you will need is a short jumper wire or even a paper clip.

Follow the directions in this link and let me know what you find.

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

I will watch for your reply.

Take care,
Joe

Welcome back:

I have a feeling the knock sensor is what is causing the problem. The computer uses the knock sensor to adjust ignition timing. If it isn't working, it is the most likely cause.

If you look at pic 1, it shows where the knock sensor (detonation sensor) is located. That needs done first. I say first because the knock sensor could be causing issues with the oxygen sensor.

There is one o2 sensor and it is located on the exhaust manifold. See pic 2. These sensor can become corroded and very difficult to remove, so two things. First, there is a special socket designed for removing them because of the wiring harness that come off them. See if the parts store will lend you that tool. Second, when you install the new one, I recommend using anti-seize on the threads of the new sensor before installing it.

One last thing, the code 13 indicates an open circuit to the o2 sensor. That means there is no connection. Before replacement, make sure the connector is properly plugged in and no wires are broken. The sensor could be fine but disconnected. And now that I think of it, the knock sensor wouldn't cause that to happen.

As far as the code 11, that indicates a malfunction in the indicator lamp circuit. That shouldn't have anything to do with the conditions you have.

Let me know if this helps or if you have other questions.

Take care,
Joe

Welcome back:

You know, I just looked again at the manual and the only one indicated is the picture I sent. However, there should be one in each exhaust manifold. Those are the upstream and then there has to be two down stream. However, I checked two different manuals and they show one.

If you can, look at the picture I sent. That is the exhaust manifold. See if both exhaust manifolds have one. Then, the down stream should be after the catalytic converter.

I have to be honest, saying there are 4 makes sense to me, but the manuals say different. It's been awhile since I worked on one. See if you can locate the others he is referring to.

Let me know.

Joe