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Discussion Starter #1
:sign0144:

Just wanted to introduce myself to the group and say hello from Wisconsin.
I drive a 99 silverado NBS. 220K! Still going strong.

I do have an issue that I'm hoping someone here can offer some help with.
The truck has no power under a load. We've checked backpressure at the 02 Sensor before the converters. That was ok. I've gotten no light lately. I had one a few months ago when the problem first came about. It was a multiple random cylinder misfire. It came once. We cleared it. It's never came up again. This problem started out small and has gotten worse in the past month. MUCH worse. New plugs/wires less than a year ago. Replaced leaking intake gasket year ago. New MAF sensor a year ago. Replaced broken manifold bolt a year ago. It sounds like there is a howl under the truck when you put it under a load and it simply has NO POWER under load either. I hate taking it to a dealer because I'm stubborn, single, and not rich enough to pay the ridiculous price to have it diagnosed. Any suggestions? Has anyone with an older NBS style silverado had to replace injectors? This truck still has the original water pump, starter, and injectors! It leaks or burns NO OIL!! It's paid for, it goes every time I start it, and it's a safe comfortable ride.
I cant part with it. It just needs a little TLC.

Thanks in advance.

C in Wisconsin.

"There is no word in japanese....for truck."
 

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Welcome aboard.


As far a your power problem a clogged converter might be your problem. Look at the converter when the truck is running and if it is glowing then it’s clogged and needs replacement.

I will leave any further diagnosis to those more familiar with your year truck.
 

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Discussion Starter #3
Never thought of that. I'll put it on my dads hoist and run it for a while to see what it looks like. Thanks!
 

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:sign0016:

The fuel filter been changed? I've had the same symptoms on our fleet of 99 Savanna's. Pretty cheap fix before you spend big bucks.:yes:
 

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:sign0016: BTW Where is Wisconsin? :rofl:

Sorry little Canadian humour there...
 

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Under pressure

:sign0016:
Good backpressure before the cat pretty much rules out a clogged cat. You say it doesn't have power under a load? What kind of load? Towing or just accelerating? Does it pull well at low speed, but not on ramp speeds?

I have experienced a clogged cat and it wouldn't accelerate well with or without towing a load. Putting around town wasn't as noticeable, but merging speeds on a freeway on ramp was when it was most noticeable.

You mentioned a 'howling' sound under load. Could point to a transmission problem. Smell any burnt almonds?

btw typical pressure before the cat should be 2-3psi. 4 psi or higher indicates excessive backpressure, which could come from the cat, the muffler or a collapsed exhaust pipe.
 

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:sign0016: BTW Where is Wisconsin? :rofl:

Sorry little Canadian humour there...
Well if we don't know where Wisconsin is we do know that Canada is America's hat:

Sorry, just a little American humor.:lol:
 

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Discussion Starter #11
Baffled. And frustrated.

:sign0016:
Good backpressure before the cat pretty much rules out a clogged cat. You say it doesn't have power under a load? What kind of load? Towing or just accelerating? Does it pull well at low speed, but not on ramp speeds?

I have experienced a clogged cat and it wouldn't accelerate well with or without towing a load. Putting around town wasn't as noticeable, but merging speeds on a freeway on ramp was when it was most noticeable.

You mentioned a 'howling' sound under load. Could point to a transmission problem. Smell any burnt almonds?



It lacks power under typical acceleration. Not towing load. It does do better at lower speeds but when I got on the on ramp to the highway this morning when it went into the last gear and then lockup, it was terribly sluggish and yes when you accelerate there is a roar under the floor of the truck. Lots of vibrations at various (higher) speeds also. There's a shudder when it's in lockup also. The fluid is good. Full clean and not burnt. We checked the pressure from the cats...it was less than 2 psi. We've gone through a few engine issues. The fuel filter is less than 3 months old and changing it improved my gas mileage. The pressure from the pump is fine. The EGR valve is fine. The MAF sensor is fine. I find it hard to believe that it's an engine related problem. The truck starts and runs really good for having
220K on it. So does anyone agree that having the transmission diagnosed first would be the right move? It's a cheaper choice I know that much.

BTW... Wiscaaaaansin is just south of Canada dere eh? You norterners oughtta look at a map sometime..ya kno!?

Thanks for the input.
 

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Sorry just had to throw this inn ..heheheh :lol:
 
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