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Engine has low power, can you help me figure out why?

Tiny
LARRY BARNES
  • MEMBER
  • 2 POSTS
  • 1996 CHEVROLET SILVERADO
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 15,000 MILES
Changed from 305 to 350. Bored 49 over with boat towing cam, vortex engine all important parts, cam sensor, crank sensor, spider injectors, distributor on and on. All new not a lot of power stumbles on cold take off unless mid grade gas no codes on computer help 40 over not 49 sorry.
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Tuesday, June 8th, 2021 AT 6:55 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check fuel pressure with a gauge. It may be because of cam with no reprogramming of computer fuel pressure should be 60-66 psi. also, check for vacuum leak. auto parts rent gauge. See link.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

and

https://www.2carpros.com/articles/engine-has-low-power-output
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Tuesday, June 8th, 2021 AT 6:55 PM (Merged)
Tiny
KRAZ1000
  • MEMBER
  • 1 POST
  • 1995 CHEVROLET SILVERADO
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
The truck listed above is the 2500 model. Replaced distributor with new Rich Porter unit, plugs, wires, fuel pump, fuel filter, MAP, TPS, IAC, fuel pressure regulator. Fuel PSI is 13. This truck has a 350 with 3.42 geared posi and it wont even spin the tires. Compression around 150 psi. Need help bad. About to find the tallest cliff and teach it to fly.
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,200 POSTS
Hi,

Honestly, the fuel pressure is perfect. Are there any noises from the engine? It's not uncommon for the cams to fail on these. It will usually cause a popping through intake, so let me know if that is the case.

Next, anytime there is an issue with power, the first thing I question is if the catalytic converter is plugged. Do me a favor. Take a look through these links. The first one discusses common symptoms related to a bad converter and the second explains how to test one.

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

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

As far as the test, if you simply remove an oxygen sensor before the converter, you should notice a difference. If there is an improvement, then the converter is my first suspect.

I attached a pic of the exhaust and circled the converter and highlighted the O2 sensor. Remove that sensor and see if it makes a change.

Let me know what you find or if you have other questions.

Take care,
Joe
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
JAKEHARGER
  • MEMBER
  • 2 POSTS
  • 1994 CHEVROLET SILVERADO
The truck is missing and backfiring, it has no power. Until I disconnect the electronic spark timing bypass. With that plug disconnected the truck runs fine. I have no idea where to go from there. The engine is timed correctly, All I can figure is a module is bad but as far as that goes I am not sure. Any help would be greatly appreciated. Thanks.
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Might be the distributor this guide can help us see what's going on

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

Please run down this guide and report back.
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
JAKEHARGER
  • MEMBER
  • 2 POSTS
It was the ECM. I checked the wiring today everything is good
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
DALE MICHALSKI
  • MEMBER
  • 6 POSTS
  • 1994 CHEVROLET SILVERADO
  • 250,000 MILES
When the truck warms up and you step on the gas pedal it doesn't respond has no power.
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good evening,

I would start by checking the fuel pressure to be sure sufficient fuel is getting to the injectors.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Any recent work done?

https://www.2carpros.com/articles/symptoms-of-low-engine-power

Did you check for any codes?

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

Roy
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
CSA1970
  • MEMBER
  • 2 POSTS
  • 1994 CHEVROLET SILVERADO
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 266,000 MILES
Truck has begun to lose power. At one point, if you stomped the throttle, it would act fine again for a little bit. Changed the MAP sensor & it really pissed it off. Now it barely idles, pressing the throttle it barely moves. Truck has a new crate engine in it with less than 12k on it. Just had new fuel pump put in, new distributor, new coil, new plugs & wires. Not sure if they changed fuel filter or not. I torn between if it's fuel filter or EGR valve. Any suggestions?
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,200 POSTS
First, check fuel pump pressure. However, to me it doesn't sound like the problem. After that, see if the EGR diaphragm is holding vacuum. If it is and you are getting vacuum to it, remove it and make sure it isn't stuck or if carbon is an issue.
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
CSA1970
  • MEMBER
  • 2 POSTS
Was the EGR valve. Still little power loss, going to clean intake, but runs much better than it did. Thanks again!
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,200 POSTS
Glad you got it fixed. What you plan is a good idea too. There could be a carbon issue in the intake where the EGR mounts.

Let me know if I can help.

Joe
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
MATTHEWCOREYWILSON
  • MEMBER
  • 3 POSTS
  • 1994 CHEVROLET SILVERADO
  • 4WD
  • AUTOMATIC
  • 189,143 MILES
Truck listed above is a 1500. Once in a while when I am accelerating at high speeds around 60 or 70 it loses power, it doesn't turn off, it just get real weak and after a couple of seconds its good again. Its done it once when I pushed the gas pushed to take off. I am thinking it's a spark plug or the timing. Would it be bad if I just went a head and bypassed the timing? Or what do you think it is? I really don't know a lot about trucks and I don't want to take it to get fixed and they rip me off.
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Are you talking about bypassing the spark advance? I would not recommend this because your fuel mileage will suffer greatly and you will more than likely see other performance issues.

Here are some guides that will help with loss of power issues:

https://youtu.be/U1RoG3I-Oww

https://www.2carpros.com/articles/symptoms-of-low-engine-power

I would recommend checking the fuel pressure when this is happening. Just hook a fuel pressure gauge and tape it to the windshield so you can watch the pressure while this is happening.
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
JMDOVER
  • MEMBER
  • 1 POST
  • 1993 CHEVROLET SILVERADO
My problem is this, when I press the gas pedal more than 1/4 of the way down it stalls and bogs. If I floor it, it down shifts and stalls. I live in east Texas (hills) and the drive to work is a pain because I slow down to 60 mph going up a hill on the hiway (70 mph zone). If I take off and try to climb a hill I do good to get it above 30 mph. Is this a fuel pump problem or a fuel filter problem or something totally different?
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
MOTORBAG
  • MEMBER
  • 4 POSTS
Please let me know what they find,Mine did the same thing.I replaced the fuel pump and it cleared up with exception of punching it at 50-60mph I get a bad bog. This guide help me find some of the problem

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

let me know what you find
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
DAVE DAUGHERTY
  • MEMBER
  • 1 POST
  • 1988 CHEVROLET SILVERADO
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 156,000 MILES
The engine will idle forever no problem. Put in drive still idles fine, put on any gas it bogs. If you give mass gas it will shut off otherwise let off gas idles fine. Put gas on a little bogs over and over cannot drive. About to lose my home over this.
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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,904 POSTS
Hello,

Lets get this truck fixed then. Two things come to mind first is a plugged catalytic converter. This guide will help you confirm or not.

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

Next would be weak fuel pump or clogged fuel filter. Here is a couple of guides to help you run some tests, if you don't have a fuel pressure gauge you can rent one for free from the auto parts store.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

and

https://www.2carpros.com/articles/how-to-change-a-fuel-filter

Please run some tests and get back to us so we can continue helping you.

Cheers, Ken

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Tuesday, June 8th, 2021 AT 6:56 PM (Merged)

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