5.3 troubles

[roll over dave]

Took truck out was running great plenty of power. Beat on it a lil not hard and got up to 220 deg usally runs at 180. And outa nowhere starts stuttering and lose of power. Any idea whats goin on

 

[wannabe]

bunch of things could cause this.. what year 5.3 is it in a truck or a rig? stock?

 

[roll over dave]

Stock 2000 model in a rig witb painless harness

 

[throttlejunkie]

Man one of my cats went bad, like within a thirty mile drive home. I never would of thought it would happen that quick, but hell I was driving it and it just started going down hill, quick. I know there are tons of things it could be, codes may help you start, but I know the first thing I will ever do now is pull the exhaust down just to rule it out, and its free. Considering I spent alot of time and money chasing my problem, goodluck.

 

[roll over dave]

Yea, that happend on my old dd but no cats on rig. Its down it before ran codez says limp mode. But why would it go into limp modd wadnt running hot and was hardly getting on it

 

[civicmindedex79]

No knock sensor codes?? Knock sensor bad or unplugged will cause that. What trans is in it? If I remember correct the 4L series can cause them the go into limp mode??

 

[roll over dave]

Trans is turbo 400 it came up as a knock sensor before. I havent changed the knock sensor. The problem comes and goes.

 

[patooyee]

The knock sensors on the engines where they are underneath the intake (like yours) are notorious for getting water logged and corroding even in stock vehicles, worse on buggies without hoods / exposed to the elements. The sensor is in a dish-shaped port that holds water. They are a crappy design and a PITA to replace. (Intake has to come off, I believe there is also a small harness that goes to them that has an updated version due to some other issue with the harness itself.) Later model LS engines moved to a different type of sensor on the lower side of the block for this and other reasons. Sometimes these issues can be intermittent but they can cause it to go into limp mode. I would say if you had a knock sensor code and it is still present this would be the place to start, especially if you didn't replace the sensors before when you knew there was a code. A lot of the time once you get the intake off it is obvious which sensor it is because it will be rusted to hell. I was just at a junkyard the other day and noticed a Tahoe with the intake off. The front knock sensor was old, but still silver. The rear one was completely brown and rusty with flakes chipping off of it and mud caked in the bowl-shaped port.

 

[roll over dave]

Thanks for all input guys, goin pull intake replace the sensor see if thats the case

 

[civicmindedex79]

I am not sure what the spec is but have have always been told to be "gentle" and torque those exactly as spec due to them being so sensitive. Maybe somebody here has had more experience installing new knock sensors???

 

[wannabe]

yes be sure and torque to spec

 

[bad80cj]

What they said do not over torq, Do not use any impact.

 

[roll over dave]

I allways use hand tools around motors I have bad luck o. Striping **** out goin look up torque specs on it

 

[1TONZR2]

I also put some RTV around the rubber plug when the new ones were put in. Keeps the water and gunk out.

Brian

 

[roll over dave]

Just. Gota find the time to tear it apart will plst up if that fixes the problem

 

[ridgetopauto]

My knock sensors went bad on my buggy. I splced into the harness and put my sensor on the side of the head in a bolt hole still working fine.

 

[Bumpers]

Re: Re: 5.3 troubles

When you replace the sensors clean the holes out very well. I think the torque spec is 12-18 lbs on them. Put some rtv around the rubber caps and seal them up good where the wire goes through and around the edge. If they are still there throw those foam pieces under the intake in the trash ...they hold in more junk then they keep out.

 

[roll over dave]

Should have time to pull it apart this afternoon. Bascially mske a dsmn around sensor. With rtv?

 

[Bumpers]

Re: Re: 5.3 troubles

Theres rubber gromets that cover the holes the knock sensors are in .. just seal the gromets up when you finish swapping sensors

 

[roll over dave]

Allrite thamks for all ur help