Runs worse now than before tune up

1992 BUICK CENTURY

152,000 MILES • 3.3L • 6 CYL • 2WD • AUTOMATIC

MINDYT

MEMBER
1 POST

I changed the plugs, wires fuel filter and oil. I drove it about ten miles and ran perfect. It has been running bad and still is ever since I spilled oil on the front of the engine, not sure if that caused the problem. the plugs and wires were connected so I do not think it hurt it. I did unplug two injectors to take a bolt off for a bracket but I put everything back together. It idles okay not that great but when it is in drive it runs really bad. now if I start off in first and shift it out manually it seems like it does better at a higher rpm's, but I can barely give it any gas before it cuts out. I checked my firing order for the plugs I think I have them right, but not positive. need some help please.

Mar 4, 2018 at 6:40 PM

STEVE W.

✓ASE Certified Mechanic
15,200 POSTS

If you changed all those parts and it ran good at first it should not be firing order related, that would have shown up instantly. Oil should not have caused this either. Your description sounds like a vacuum leak. Possibly a hose was loosened and fell off on the drive. I would check the vacuum lines first, loose, off, cracked lines would all be suspect on an elderly engine.
Next I would check the timing, another issue with an older engine could be a loose timing chain that jumped. It could cause this as well.

Image (Click to enlarge)

Professional Diagram for 2CarPros Members
Click here to log in and view diagram.

Mar 6, 2018 at 1:43 AM

Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.