1999 Chevy Silverado - Sluggish Acceleration?

**purecomedy** · 11-14-07, 01:02 AM

Took my dad's truck for a spin and it sure seems to have some loss of acceleration and it's only around 130,000 km. I'm wondering if there's a problem somewhere like bad intake sensors or something.

Basically what I notice is unless you really baby it with slow acceleration the engine kind of pauses and sucks in a huge amount of air any time you press the pedal in an assertive way.

After 130,000 km surely the truck couldn't lose that much compression that it would have significantly less power would it?

....or am I just too used to driving a Honda with a responsive engine and Chevy trucks are just really finicky on the throttle?

**downhill** · 11-16-07, 10:14 PM

I've had problems like this several times. Maybe a fuel pump going bad.

Once when the truck I had was warmed up it would do this. That one was a catalytic converter.

**purecomedy** · 11-17-07, 12:32 PM

Originally Posted by downhill

I've had problems like this several times. Maybe a fuel pump going bad.

Once when the truck I had was warmed up it would do this. That one was a catalytic converter.

Interesting, not sure what the symptoms of a bad fuel pump would be....maybe you're right.

It's hard to say but I was thinking more along the lines of the engine kicking into fast idle even when it wasn't that cold. It seems like a weird thermostat, sensor or choke setting.

I know about 15 years ago my dad had his exhaust replaced (in another GM vehicle) and in the process they took out his catalytic converter (how times have changed!). I recall that he said the car seemed to perform worse rather than better which surprised me. You'd think in most cases reducing any back pressure would be good.

Know of any good automotive forums where I could pose the question to get some more opinions?

**Easto** · 11-17-07, 12:47 PM

Mass air flow sensor?

**purecomedy** · 11-17-07, 05:54 PM

I thought something like that too...

**Bastid** · 11-18-07, 12:02 PM

maybe run some fuel injector cleaner through it see if it helps... i am assuming it has a FI system being a '99 and no other specs.

**purecomedy** · 11-20-07, 02:09 PM

Originally Posted by Bastid

maybe run some fuel injector cleaner through it see if it helps... i am assuming it has a FI system being a '99 and no other specs.

He runs fuel injector cleaner through there every 3 months.

Talking to a chemist at work a few years ago he actually said that he thought there is as much a chance that fuel injector cleaner additives would cause gumming up of injectors. The way he put it was that there are a lot of factors in creating clean combustion and 1 bottle doesn't cover all of those possibilities.

I don't know who to believe. Every 50,000 km or so maybe get them to manually clean off your injectors. That's the most effective way.

**Chris** · 11-21-07, 03:46 PM

Hows the temparature gauge?
If its a little/ not alot, but a little higher then it should be, cat convertor may be plugging up

**purecomedy** · 11-23-07, 09:56 PM

Originally Posted by Chris

Hows the temparature gauge?
If its a little/ not alot, but a little higher then it should be, cat convertor may be plugging up

If anything I'd say it's too cold not too hot. Remember, this is in Canada and winter is approaching.

**jasonb31** · 02-23-08, 04:09 PM

The only true way to clean fuel injectors is with the kit that you buy. It plugs into the high pressure fuel pressure test fitting in the fuel rail and you run the engine off of the tank of cleaner that you get in the kit. Take the truck to Auto Zone and they will plug into the computer and read any codes for you.

**xekushnr** · 02-23-08, 04:15 PM

I'd say test the O2 sensors and make sure they are still operating in spec. If one sensor thinks the car is running rich, it will cut down on fuel and you will have a loss of power.

Is it gas or diesel?

**helter** · 02-28-08, 06:23 PM

Originally Posted by purecomedy

Took my dad's truck for a spin and it sure seems to have some loss of acceleration and it's only around 130,000 km. I'm wondering if there's a problem somewhere like bad intake sensors or something.

Basically what I notice is unless you really baby it with slow acceleration the engine kind of pauses and sucks in a huge amount of air any time you press the pedal in an assertive way.

After 130,000 km surely the truck couldn't lose that much compression that it would have significantly less power would it?

....or am I just too used to driving a Honda with a responsive engine and Chevy trucks are just really finicky on the throttle?

Changed fuel filter in the last 15K miles?
If not, start there, its $30 and easy to do. Once it starts getting trash it clogs and reduces the amount of gas the pump can run through the lines. You usually hear a fuel pump going bad in my experience.

**joecool169** · 02-28-08, 07:07 PM

Originally Posted by jasonb31

The only true way to clean fuel injectors is with the kit that you buy. It plugs into the high pressure fuel pressure test fitting in the fuel rail and you run the engine off of the tank of cleaner that you get in the kit. Take the truck to Auto Zone and they will plug into the computer and read any codes for you.

Actually motovac is the only way.

**joecool169** · 02-28-08, 07:08 PM

Originally Posted by xekushnr

I'd say test the O2 sensors and make sure they are still operating in spec. If one sensor thinks the car is running rich, it will cut down on fuel and you will have a loss of power.

Is it gas or diesel?

O2 sensors would set the check engine light. A lazy or non switching O2 will cause the computer to change air fuel mixture to much. Sets code.

**SeedOfChaos** · 03-04-08, 02:45 PM

Originally Posted by helter

Changed fuel filter in the last 15K miles?
If not, start there, its $30 and easy to do. Once it starts getting trash it clogs and reduces the amount of gas the pump can run through the lines. You usually hear a fuel pump going bad in my experience.

I think this is a good idea, and also you may want to have a look at the air filter before you do anything more expensive. If the engine can't breathe, it will also be sluggish.

**jasonb31** · 03-05-08, 07:23 PM

Originally Posted by joecool169

Actually motovac is the only way.

Thats what I was talking about. What other system screws into the high pressure line and cleans the fuel system while also feeding the engine to run?

**evttech30** · 06-12-12, 10:04 PM

I actually have one in my shop with the same symptom. I have found a bad mass air flow sensor. Essentially not allowing enough air to flow into the engine while under a heavier load. Replace the sensor. Its the second 99 ive come across with this issue and both times thats what its been. Good luck