Could there be a connection between the engine shaking, the cruise control error code

[1994buick]

Serv Eng Soon light came on in my 1994 Buick LaSabre. On one day the code read 02 sensor. On another day it read error code for Cruise Control but did not read O2 sensor that day. mechanic replace sppark plugs. also alternnator...but did not replace 02 sensor. Next day after plugs changed my engine shaking at speeds of 45 to 55 mph. Now mechanic said I need replace transmission. A very knowledgeable friend drove it and looked at it as a favor. He is retired from 30 years as Head of Service for GM north east Division. He said it is NOT transmission although he could not pin down problem just by driving it and looking at things in my driveway. He said to take it to the Buick dealer service dept for their diagnosis. The Buick shop says it's shaking because there is a problem in injector wiring. Says that signal is not getting from injector #5 to Power Control Module. (Buick dealer also saw an 02 sensor code...But did NOT get a Cruise Control code. NOW HERE IS THE PRPBLEM: I made an appointment at the Buick Service Dept (for tomorrow) to find the fuel injector wiring problem ..and they say they may possibly have replace the Power Module. BUT when I was driving the car on Saturday (staying below 45 mph) I used cruise control and then shut it off. I repeated that again. After that action the engine had no more shaking. I drove it again today...still no shaking. Service eng light is still on though...but car runs great. Does anyone know if there is a connection why the shaking went away after I used the cruise control and then shut it off? ***Since the engine is no longer shaking at any speed intend to cancel my appointment about a fuel injector wiring problem. However I will get the o2 sensor replaced at an independant shop. I assume the Buick Dealer would charge much higher to replace 02 sensor ...which is not an intricate job that requires a Buick shop.

[LeSabre97mint]

94buick

Just because you get an 02 sensor error doesn't mean your sensor is bad. It could be. However, there are a lot of things that can give a 02 error such as a vacuum leak can give a lean error. I know there are a lot of 02 sensors in the garbage.

I don't think the cruse caused the engine shaking unless it was causing a vacuum leak causing a miss on one or more cylinders.

Regards

Dan

[1994buick]

Thank you. I wonder why the Buick dealer didn't mention the idea of a about a vacuum leak. (The first mechanic I saw said that he found lower ppressure on the 5th cyclinder. The Buick serv department is saying a wiring problem that causes the fuel injector on #5 to not send (or receive??) to (or from?) the Power Control module.
Just about 30 minutes ago I drove the car and the first 10 minutes....no shaking at various speeds, the light actually was off. After a while the light came on...and also, after a while the SHAKING RETURNED.
What kind of repair would be needed to fix a vacuuum leak?
How do I know if I am wasting my time asking for a new 02 sensor?
jeeze...this is a pain. i am not a car person...and now I don't know if I should take it in to the dealer in the morning and let them do the thing about looking a wiring problem. It can be awfully expensive to just be guessing.

Originally Posted by LeSabre97mint

94buick

Just because you get an 02 sensor error doesn't mean your sensor is bad. It could be. However, there are a lot of things that can give a 02 error such as a vacuum leak can give a lean error. I know there are a lot of 02 sensors in the garbage.

I don't think the cruse caused the engine shaking unless it was causing a vacuum leak causing a miss on one or more cylinders.

Regards

Dan