Engine loss of power?

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
I'm glad you got it fixed. If you have questions in the future, let us know.

Joe
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Tuesday, December 15th, 2020 AT 2:44 PM (Merged)
Tiny
COLDFIRE1968
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  • 2 POSTS
  • 1997 DODGE RAM
  • V8
  • 4WD
  • AUTOMATIC
  • 181,000 MILES
1997 dodge will not go over 40 mph, 5.9 liter 4x4
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Tuesday, December 15th, 2020 AT 2:44 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
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Is the Check Engine light on? If it runs unusually smoothly, suspect a plugged catalytic converter. That will also cause the exhaust at the tail pipe to sound like a steady hiss rather than the normal "putt putt".

Caradiodoc
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Tuesday, December 15th, 2020 AT 2:44 PM (Merged)
Tiny
COLDFIRE1968
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  • 2 POSTS
Check engine light is on and when I took it to auto zone to check it sai misfire on 1 3 5 cylinders
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Tuesday, December 15th, 2020 AT 2:44 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
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Dandy. That's the left bank of the engine. Most likely those codes did not all set at the same time. The Engine Computer can detect a single cylinder misfire, of which you have three, and it can detect a multiple cylinder misfire, which it did not. Multiple cylinder misfires occur at the same time and will be related to something they have in common such as a bad sensor reading, low fuel pressure, contaminated fuel, or a vacuum leak.

A single cylinder misfire is caused by something that is related to just that one cylinder such as the spark plug, plug wire, injector, or burned valve. Given the nature of the codes, (multiple single cylinder misfires), I'd start by looking at a combination of those generalizations. That means multiple items related to a single cylinder. A perfect example would be high-mileage spark plugs and wires. A worn spark plug will cause random misfires in one cylinder, but just as two tires wear out at the same rate, so does a set of spark plugs.

If the left front oxygen sensor incorrectly reports a rich condition, the Engine Computer will reduce the pulse width to all four injectors on that bank. It can't tell which cylinder is running rich. It can only adjust the mixture to all four cylinders together. That could result in misfires from a fuel / air mixture that is too lean.

That oxygen sensor could also be responding correctly. O2 sensors do not detect unburned fuel, only oxygen, but some of the normal oxygen in the exhaust will be burned with that extra fuel before it reaches the sensor. The sensor will take longer than normal to detect the lean part of the cycle. In this case, a leaky injector would be suspect. Assuming the computer is reducing fuel to the entire left side of the engine which is resulting in the misfires, suspect the injector for cylinder number 7 which is not misfiring.

If spark plugs and wires don't solve the problem, consider switching the injector from cylinder number 7 with one on the passenger side to see if the misfires go to the other side.

Caradiodoc
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Tuesday, December 15th, 2020 AT 2:44 PM (Merged)
Tiny
CYRUS78410
  • MEMBER
  • 5 POSTS
  • 1996 DODGE RAM
  • V8
  • 4WD
  • AUTOMATIC
  • 128,000 MILES
On the highway, my truck will not over 65 mph. What could be going wrong?

Just had a recent tune-up. Have a new set of plugs, wires, and distributor cap.

At lower speeds, my truck is fine.

However, when trying to go up to 70 or higher engine just starts revving, getting loud and I cannot go any higher than 65.
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Tuesday, December 15th, 2020 AT 2:44 PM (Merged)
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
This sounds like you have a plugged catalytic converter that is plugged, but to be sure check out these two guides to confirm the issue.

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

and

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please run down these guides and report back.

Cheers
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Tuesday, December 15th, 2020 AT 2:44 PM (Merged)
Tiny
CHRISCON
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Thanks for this post. I had this problem as well, I had to have the catalytic converters replaced for $650.00 back to normal. ;) I love this site.
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Tuesday, December 15th, 2020 AT 2:44 PM (Merged)
Tiny
CODY EDWARDS
  • MEMBER
  • 4 POSTS
  • 1996 DODGE RAM
  • V10
  • 4WD
  • AUTOMATIC
I have a 1996 dodge v10 that is trying to load up, it is going through mass amounts of fuel, blowing smoke, and lots of power loss. I have changed the map sensor and replaced the o2 sensors 4 months ago. What else could be the cause?
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Tuesday, December 15th, 2020 AT 2:45 PM (Merged)
Tiny
PROTECH1980
  • MEMBER
  • 901 POSTS
Are there any diagnostic trouble codes?/Check engine light
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Tuesday, December 15th, 2020 AT 2:45 PM (Merged)
Tiny
BABA GHANOUSH
  • MEMBER
  • 1 POST
The catalytic converter may be plugged. Take it to a good exhaust
shop and they can run a pressure test on it. Or, bang on the
catalytic converter with a good sized hammer and try to loosen up
the plugged area. Have you noticed any honey-comb looking stuff coming out of the exhaust? This is the cat's inards coming apart and getting blown out back.
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Tuesday, December 15th, 2020 AT 2:45 PM (Merged)

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