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2005 silverado 5.3L feels sluggish - HELP


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Bear with me I want to give the most detail so I can get some accurate responses. All help is greatly appreciated.

 

I have a 2005 silverado 1500 z71 crew cab with 130k miles on it. I bought it used about 7 months ago and feel it just doesn't have the power that all of my trucks in the past have had. I had a 98 single cab W/T with a 4.3L that seemed to have just as much giddy up. I also had an 09 2wd ext. cab with a 5.3L that had much more. All of the trucks have been stock with the exception of a flowmaster super 40 on the 98 and an unknown brand exhaust on the 09 (it was on there when I bought the truck.) I also had a 2012 ram with the 5.7 but I don't feel that's apples to apples in this case but it had tons more power from a 1/2 ton truck than this 05.

 

The problem isn't reaching highway speeds. The truck will run 70-80mph in the 1800-2200rpm range without problems. It does feel like it works pretty hard climbing hills at highway speeds however. It also seems sluggish when merging onto the highway or passing. Once at highway speeds it downshifts fine but seems to have no torque to pick up speed to pass despite the rise in RPMs. I have to put the pedal almost to the floor when accelerating to get up to highway speeds when merging but once it's there it cruises at that speed fine. Transmission is good and engine starts, runs, and idles fine. The only problem is the felt power and acceleration issue.

 

1. Is this normal or has anyone had the same experience with this year/model?

2. If it's not normal what should I check to try to fix it?

3. If it is normal I would like to improve the performance. What would be some basic things I could replace such as exhaust, CAI, etc.

 

 

I have SLIGHTLY bigger than stock tires, 285/65r17 A/T I think, that don't rub with stock ride

I have a brush guard as well (not a full ranch hand style bumper just the brush guard.)

 

I don't think these additions would affect it much but thought it would be worth adding to the description.

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My question would be what motor do you have?

 

Base engine size 4.8 L 5.3 L 4.3 L Base engine type gas gas gas Cam type Overhead valves (OHV) Overhead valves (OHV) Overhead valves (OHV) Cylinders V8 V8 V6 Horsepower 285 hp @ 5200 rpm 295 hp @ 5200 rpm 195 hp @ 4600 rpm Torque 295 ft-lbs. @ 4000 rpm 330 ft-lbs. @ 4000 rpm 260 ft-lbs. @ 2800 rpm Valves 16 16 12

 

 

What axle ratio that you have? Look at the option codes in the glove box or on the door? Those codes will begin with the letter " G ".

 

GT4 Rear axle, 3.73 ratio
GU4 Rear axle, 3.08 ratio
GU5 Rear axle, 3.23 ratio
GU6 Rear axle, 3.42 ratio

 

starman suggested the following items:

 

New plugs

New wires

Fuel injector cleaner

Fuel quality
Fuel filter

Clean the mass air flow sensor

New air filter

Vacuum leaks

Alignment

Brake drag

Check engine codes

Exhaust leaks

Transmission slipping

Dirty throttle body

Burnt valves

Clogged fuel injectors

Low compression (rings)

 

All good points. Let's see first what we have for power delivery first before we change a thousand dollars in parts.

 

Start to inspect the obvious, like New air filter, Fuel filter, Fuel quality and available engine codes. Please don't change parts on guesstimates, lets see what's going on. Find a scan tool that reads data. That will help us a lot. The engine data will tell us what the engine is doing overall.

 

Personal note: your tires are 2 sizes too big for the truck which "reduces" accelerating power. Great for highway cruising, poor for needing torque / acceleration.

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My question would be what motor do you have?

Base engine size 4.8 L 5.3 L 4.3 L Base engine type gas gas gas Cam type Overhead valves (OHV) Overhead valves (OHV) Overhead valves (OHV) Cylinders V8 V8 V6 Horsepower 285 hp @ 5200 rpm 295 hp @ 5200 rpm 195 hp @ 4600 rpm Torque 295 ft-lbs. @ 4000 rpm 330 ft-lbs. @ 4000 rpm 260 ft-lbs. @ 2800 rpm Valves 16 16 12

 

 

What axle ratio that you have? Look at the option codes in the glove box or on the door? Those codes will begin with the letter " G ".

 

GT4 Rear axle, 3.73 ratio

GU4 Rear axle, 3.08 ratio

GU5 Rear axle, 3.23 ratio

GU6 Rear axle, 3.42 ratio

 

starman suggested the following items:

 

New plugs

New wires

Fuel injector cleaner

Fuel quality

Fuel filter

Clean the mass air flow sensor

New air filter

Vacuum leaks

Alignment

Brake drag

Check engine codes

Exhaust leaks

Transmission slipping

Dirty throttle body

Burnt valves

Clogged fuel injectors

Low compression (rings)

 

All good points. Let's see first what we have for power delivery first before we change a thousand dollars in parts.

 

Start to inspect the obvious, like New air filter, Fuel filter, Fuel quality and available engine codes. Please don't change parts on guesstimates, lets see what's going on. Find a scan tool that reads data. That will help us a lot. The engine data will tell us what the engine is doing overall.

 

Personal note: your tires are 2 sizes too big for the truck which "reduces" accelerating power. Great for highway cruising, poor for needing torque / acceleration.

17e45254932f905700939dfc33a3b450.jpg

 

 

 

Thanks for the responses

 

5.3 L vortec

It looks like 3.42 axle ratio?

I've replaced the air filter, cleaned the MAF sensor and throttle body.

Haven't checked fuel filter but I usually get fuel (87 octane) at QT.

Can I "check" the fuel filter? Sorry for the ignorance but I've never done it. Just replaced it on my '98.

As far as engine codes will there be some that aren't causing a light on the dash? It hasn't been showing any lights or messages. It had an Evap leak code about a month ago but I replaced the purge valve and it cleared the code.

Tires are actually 285/70 17s on a stock 17x7.5 wheel. Didn't think that would cause THAT much of an acceleration problem.

Haven't checked plugs and wires but the previous owner stuck to all of the periodic maintenance down to the diff. Fluid changes. Not sure when/if the plugs or wires have been changed though.

The transmission FEELs good. It shifts smooth and doesn't have any delay shifting between gears or even into reverse. It downshifts fine when I step on the gas just doesn't have any giddy up if that makes sense. The torque doesn't seem to match the RPMs

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No serviceable fuel filter externally on '05, unless it is designated a flex fuel. Then there may be one.

 

No linkage, Starman. Wire/electronic Can still observe opening though

 

You might check fuel pressure reading. Key on, engine off. Report back.

 

Probably going to take a custom tune to get everything out of it you want. Torque management can be an issue and the speedo/tire difference may play into it also

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No serviceable fuel filter externally on '05, unless it is designated a flex fuel. Then there may be one.

 

No linkage, Starman. Wire/electronic Can still observe opening though

 

You might check fuel pressure reading. Key on, engine off. Report back.

 

Probably going to take a custom tune to get everything out of it you want. Torque management can be an issue and the speedo/tire difference may play into it also

Check the fuel pressure reading? Something I can check or do I need it hooked up to a reader?

 

Had someone else say possibly clogged cats? Not sure what other symptoms it would cause but the truck runs fine at low speeds it has decent torque accelerating off of the line, but once I'm going above probably 45-60 if I try to pass or pick up speed quicker the RPMs will rev to around 4000-4500 when it downshifts but it has little response in torque.

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Having a 3.42 gear is an "all around" gear ratio, not a stump puller. Ran your tire sizes through the calculator, the tire size change has zero effect on gear change.

 

Tire size change / gear ratio calculator hyperlink: https://tiresize.com/gear-ratio-calculator/

 

What I don't like is how high your engine has to spin to get maximum torque (pulling max torque power @ 4000 rpm's) and you run half that most of the time. Most of the people "never" look at the full torque rpm level, they just see how much.

 

 

Also here is your "spec sheet"

 

http://www.new-cars.com/2005/chevrolet/chevy-silverado-specs.html

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Having a 3.42 gear is an "all around" gear ratio, not a stump puller. Ran your tire sizes through the calculator, the tire size change has zero effect on gear change.

 

Tire size change / gear ratio calculator hyperlink: https://tiresize.com/gear-ratio-calculator/

 

What I don't like is how high your engine has to spin to get maximum torque (pulling max torque power @ 4000 rpm's) and you run half that most of the time. Most of the people "never" look at the full torque rpm level, they just see how much.

 

 

Also here is your "spec sheet"

 

http://www.new-cars.com/2005/chevrolet/chevy-silverado-specs.html

What do you mean when you say you don't like it?

Thanks for the info so far.

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Fuel pressure gauge can be borrowed from many parts stores. Probably not the problem, but when I had one going bad I suffered from some of what you describe

Ah ok thanks for the help. I'm going to inspect the plugs possibly replace plugs and wires and probably run some sea foam and see if it helps at all. May also look at an air raid drop in tube and aftermarket filter when I get some cash. There's a ton of things it could be it seems and it's just going to be a process of elimination.

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Stock filter and tube flow plenty of air. Probably been mentioned, check cats for flow. In the end you may fine you simply need a tune to get more out of your rig to satisfy your butt dyno. I know on my '04 and almost every model since, I've been displeased with the acceleration characteristics. After tuning I don't need to have force a downshift to be able to pass easily or just simply accelerate easily. But first rule out any issues prior to tune

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rppyro,

Your statement needs to be answered. (Mine) "What I don't like is how high your engine has to spin to get maximum torque (pulling max torque power @ 4000 rpm's) and you run half that most of the time. Most of the people "never" look at the full torque rpm level, they just see how much.

Every motor has a torque /horsepower curve. That torque curve (feel in the pants power) can be amplified or hindered by what things can effect that torque curve. I'll stick to your truck as much as possible.

 

Before everybody gets lost in what I'm pointing out certain terms need to be explained since everybody focuses on horsepower. The statement is: Horsepower is "HOW FAST" something can be done, ...but torque is "HOW MUCH" can be done at a certain speed.

 

Your torque / horsepower curve on the LM7, 5.3 liter Vortec has 330 foot pounds @ 4000 rpm's with 310 horsepower @ 5000 rpm's whereas if you look at the same spec sheet provided, the LQ4, 6.0 liter, Vortec provides a much earlier torque peak at 360 @ 4000 rpm's with 300 horsepower @ 4400 rpms's

 

Every vehicle has a torque to horsepower, the amount of the vehicle's weight it's pulling, gearing provided, aerodynamic drag ratio to deal with going down the road factor.

 

Torque is much more important on heavier vehicles than lighter vehicles whereas the much lighter vehicles have to worry more about horsepower less on torque.

 

For entertainment look at semi truck engine horsepower / torque specs. Torque is higher than horse power ratings at lower rpm's compared to any gas motor. There is a reason for this.

 

Everybody equates higher rpm's means more horsepower, more torque equals faster acceleration. Well, when you dealing with something heavy on the street, it's the reverse. Your looking for torque to come in early as possible. 99% of the public operate their vehicles under the 4000 rpm band. You stated that your motor spins at 1800 to 2200 rpm's. That's hovering at 50% of your available maximum torque power and 40% of you maximum horsepower. When you are dealing with "street trucks", you want the torque / horsepower to come in early, not later.

 

As for making comparison's on previous owned trucks, it comes down to when the horsepower / torque came in, the overall gearing, the weight of the truck and the aerodynamic drag. Seeing those factors, I can understand your concern on the lack of power.

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rppyro,

Your statement needs to be answered. (Mine) "What I don't like is how high your engine has to spin to get maximum torque (pulling max torque power @ 4000 rpm's) and you run half that most of the time. Most of the people "never" look at the full torque rpm level, they just see how much.

Every motor has a torque /horsepower curve. That torque curve (feel in the pants power) can be amplified or hindered by what things can effect that torque curve. I'll stick to your truck as much as possible.

 

Before everybody gets lost in what I'm pointing out certain terms need to be explained since everybody focuses on horsepower. The statement is: Horsepower is "HOW FAST" something can be done, ...but torque is "HOW MUCH" can be done at a certain speed.

 

Your torque / horsepower curve on the LM7, 5.3 liter Vortec has 330 foot pounds @ 4000 rpm's with 310 horsepower @ 5000 rpm's whereas if you look at the same spec sheet provided, the LQ4, 6.0 liter, Vortec provides a much earlier torque peak at 360 @ 4000 rpm's with 300 horsepower @ 4400 rpms's

 

Every vehicle has a torque to horsepower, the amount of the vehicle's weight it's pulling, gearing provided, aerodynamic drag ratio to deal with going down the road factor.

 

Torque is much more important on heavier vehicles than lighter vehicles whereas the much lighter vehicles have to worry more about horsepower less on torque.

 

For entertainment look at semi truck engine horsepower / torque specs. Torque is higher than horse power ratings at lower rpm's compared to any gas motor. There is a reason for this.

 

Everybody equates higher rpm's means more horsepower, more torque equals faster acceleration. Well, when you dealing with something heavy on the street, it's the reverse. Your looking for torque to come in early as possible. 99% of the public operate their vehicles under the 4000 rpm band. You stated that your motor spins at 1800 to 2200 rpm's. That's hovering at 50% of your available maximum torque power and 40% of you maximum horsepower. When you are dealing with "street trucks", you want the torque / horsepower to come in early, not later.

 

As for making comparison's on previous owned trucks, it comes down to when the horsepower / torque came in, the overall gearing, the weight of the truck and the aerodynamic drag. Seeing those factors, I can understand your concern on the lack of power.

Simplest way to fix the problem? If there is one.

The 09 I had had the 5.3 in it as well but it seemed to have more torque in the low end. It also had the stock tires on 20" wheels (Goodyear eagle ls2) it was a 2wd ext. cab flex fuel though if that may have made a difference?

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