1997 GMC Safari Rough running

1997 GMC SAFARI
240,000 MILES • 6 CYL • 2WD • AUTOMATIC
Avatar
JOHNSON VIKING
  • MEMBER
  • 1 POST
My safari seems to missfire.
This occures while cruising only....that is while doing about 65 MPH on the highway. It seems to accelerate fine and is ok when I let off the gas.

It seems to get worse in colder weather.

The problem is getting slowly worse.

Thanks
Dec 11, 2008 at 8:58 AM
Advertisement
Avatar
RASMATAZ
  • ✓ASE Certified Mechanic
  • 75,992 POSTS
  • ASE Certified Mechanic
Do you have a check engine light and when was the last tune-up ?

Misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.
Dec 11, 2008 at 9:20 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
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.