engine vibrates 4th/5th gear when driving uphill

1997 MAZDA B2300
110,000 MILES • 4 CYL • 2WD • MANUAL
Avatar
LGSASKI
  • MEMBER
  • 1 POST
I have a 1997 Madza B2300 truck shortbed that runs very rough in forth and fifth gear when going up hills. As long as the truck is driven on "level" roads, the car runs fine. It has been in a couple of mechanic shops and I've did/had done some preventive maintenance but the problem continues.
Changed oil to a lighter weight per owner's manual. This did improve the engine's performance.
Changed shark plugs/wires. Problem continued.
Changed timing belt. Problem continued.
Checked Mass Air Flow Sensor/okay. Problem continued.
Ford deslership checked the PCM proportional/okay. Problem continued.
Checked catalyist converter/okay. Problem continued.
Mar 21, 2011 at 10:46 PM
Advertisement
Avatar
FIXITMR
  • ✓ASE Certified Mechanic
  • 9,990 POSTS
  • ASE Certified Mechanic
sounds like a spark/mixture issue under extreme load. maybe EGR is causing leanness? or coil is shorting under load? does it have a distributor? then cap and rotor or module?
May 27, 2011 at 7:54 PM
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.