Rough running, loss of power and backfiring

1994 FORD RANGER
193 MILES • 4.0L • 6 CYL • 4WD • MANUAL
Avatar
KARENRIDINGS
  • MEMBER
  • 3 POSTS
It started with head gaskets. i replaced both heads ,gaskets ,plugs, coil ,plug wires ,spark plugs, throttle position sensor, fuel injectors, crank shaft sensor, idle air sensor. i have changed the oil, mass air flow sensor. Checked the timing and it's in time. slave cylinder, water pump, power steering pump, master cylinder, fuel filter and fuel pump. it ran fine for one day and then it started running rough again. no power ,it backfires through the intake whenever i give it gas.
Oct 10, 2020 at 6:46 PM
Advertisement
Avatar
ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
Good morning,

No power and backfiring usually is an indication of timing.

https://www.2carpros.com/articles/engine-backfires-while-running

https://www.2carpros.com/articles/engine-has-low-power-output

I would start with testing the compression to be sure the timing has not changed. If the timing is retarded, it will backfire out the intake. Did you replace the guide and the tensioner on the timing chain?

https://www.2carpros.com/articles/how-to-test-engine-compression

Roy



Image (Click to enlarge)
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Oct 10, 2020 at 10:50 PM
Avatar
KARENRIDINGS
  • MEMBER
  • 3 POSTS
Already checked the timing, it's in time.
Oct 10, 2020 at 10:53 PM
Avatar
KARENRIDINGS
  • MEMBER
  • 3 POSTS
The only thing i haven't replaced is the 02 sensor.
Oct 10, 2020 at 10:54 PM
Avatar
ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
This is not a parts replacement issue.

What is the compression as I suggested you test? I ask because I need to see if it could be a rocker arm not working. I attached a picture of the shaft and the torque spec for the installation. Did you torque it to the proper specs?

Did you replace the guide and tensioner?

Roy

Image (Click to enlarge)
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Oct 10, 2020 at 11:10 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.