Rough running, loss of power and backfiring

KARENRIDINGS

MEMBER
1994 FORD RANGER
4.0L
6 CYL
4WD
MANUAL
193 MILES

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.

4 Replies

ASEMASTER6371

MECHANIC
52,797 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

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Sunday, October 11th, 2020 AT 5:50 AM

KARENRIDINGS

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3 POSTS

Already checked the timing, it's in time.

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Sunday, October 11th, 2020 AT 5:53 AM

KARENRIDINGS

MEMBER
3 POSTS

The only thing I haven't replaced is the 02 sensor.

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Sunday, October 11th, 2020 AT 5:54 AM

ASEMASTER6371

MECHANIC
52,797 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

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