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2006 Silverado 1500 Issues after replacing knocksensors and intake gaskets


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So I just replaced my knock sensors and wiring and also new felpro Intake gaskets, now it starts up. It when it starts it stays high in idle then slowly comes down kinds like I’m on the gas and slightly letting off little by little . But I also cleaned out the throttle body since it was a little built up with carbon, but when I did these things then back knock sensor was complete corroded and the front was ok so I did the dam thing with the red rvt for the water and also the felpro gaskets we’re different then my original ones they Didn’t clip on to the intake like the old ones they laid in the head bolts with little eye lits ,don’t know if that is a problem. But so I started the truck and it did as I mentioned and when I gave it gas it kind of sputtered until it hit about 1600rpm then reved up noramally but if I let it drop to a idle again and stab it it does it again then I drove it around and it seems the idle is staying up even when I’m off the gas and is still pushing the truck forward until I stop all the way then it will come down to a idle of 7-800 again. Help me out I’m lost with this one 

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Does your truck have the upper intake Plenum as they have on the 04 Tahoe? I have the 04 with the 4.8 and have knock sensor codes and have to remove the upper intake Plenum to replace the knock sensors.

Did you torque the sensors, torque the intake Plenum gasket if that's what you have or if you have regular intake did you torque that properly and torque the throttle body as well as other things that needed properly torqued.

I can't remember if 06 or 07 they switched body styles again? I wouldn't think it would make much of a difference with the engine's though.

Just what your describing almost sounds like a vacuum leak. Did you get all hoses back on? IF so maybe take some brake parts cleaner, very little and spray lightly around the gasket areas. IF you have a leak the rpm's will increase wherever the leak is.

You can always spray water as well it'll just clean the top of the pistons when it steams them.


Did you verify the knock sensors were bad before replacing them and then once replaced make sure they're working properly? A labscope makes this easy if you have one.

Were you getting codes showing the knock sensors were bad initially?

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When you cleaned the throttle body you didn't manually force the flap open did you? There's a way you can get it to open and clean it that way being that the vehicles are drive by wire anymore with no throttle cable. Any other codes?

Did you clear the engine codes, key back off then key back on before starting? Also does it do this after fully warmed up or was it just initially? How did it use to start prior to the code? Had you had the code for a long time? IF none of that helps head over to scanner Danner.com and create an account and post in the forums there. Make sure to include all information required when posting. Great techs over there, top notch!! Also copy and paste or link this thread so they know what you've did and don't have to type it all over again.

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So yea I opened up the throttle manually didn’t know another way was possible and I torqued everything back to spec and I did have a code on for a while for the knock sensor and the rear knock sensor was completely corroded and also bank 1and 2 lean so I assumed the  intake gasket as everyone referred it too and I’ll check again all the hoses and I also heard of a PCv valve problem could that be a issue? And before I tore it apart it started to act up like seriously as I started to pull in the drive way to take it apart it start idleing all crazy almost like starving for fuel and that was the only time that has happened . And so I forgot to mention I took it too autozone to use there fuel pressure tool and on the key on position it jumped to 50psi and while running it was sitting at 60 so I don’t know if that’s a problem or maybe a fuel filter 

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  • 2 months later...

I know this is an old post, but I wanted to contribute some information for others' reference. These drive-by-wire systems (electronic TB) can automatically adjust the position of the throttle plate to compensate for gunk that builds up in the throttle body. Since this happens over time, when you clean your throttle body, the computer has to basically relearn the correct throttle position. I had the exact same thing happen to me when I cleaned the TB on my 2007 Silverado Classic. It took a few days of driving for the computer to relearn the correct throttle plate position, and the issue took care of itself.

 

I'm going to speculate that the lack of activity in your post since it was first created means your issue also worked itself out.

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  • 2 weeks later...

I also didn't realize he'd replied until today as I was busy with life. I wonder if it was the upper intake Plenum. Luckily with the stumbling noise he didn't have the fuel smell as in the Rust Belt the salt gets on top of the fuel tank and around the fuel tank line. It corroded mine all the way through a couple years ago. Had to replace the fuel pump because at rest with the engine shut off the pressure would drop as soon as I turn the engine off at a very decent pace.

Now that I recall it was 2006 they switched them, the body style over. He could check to see if there's any TSB updates. I have to do the knock sensors, upper intake plenum gasket and I'm going to replace the wiring harness since I'm already in there and do the red RTV silicone Dam to keep water out and the rust down from ruining the new knock sensors.

You're correct on him needing to let the vehicle learn the idle over a few days. I wonder if he is did his hundred thousand mile service which would be new plugs, wires. Also might not hurt to check the air filter. If you're at a hundred thousand miles then it might be good to get a fuel injection service as that will help clean the injectors up for a good spray pattern and help with fuel economy and even pressure throughout all the injectors.


I would be curious as to what the original poster found that eventually solved his issue.

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So yea I opened up the throttle manually didn’t know another way was possible and I torqued everything back to spec and I did have a code on for a while for the knock sensor and the rear knock sensor was completely corroded and also bank 1and 2 lean so I assumed the  intake gasket as everyone referred it too and I’ll check again all the hoses and I also heard of a PCv valve problem could that be a issue? And before I tore it apart it started to act up like seriously as I started to pull in the drive way to take it apart it start idleing all crazy almost like starving for fuel and that was the only time that has happened . And so I forgot to mention I took it too autozone to use there fuel pressure tool and on the key on position it jumped to 50psi and while running it was sitting at 60 so I don’t know if that’s a problem or maybe a fuel filter 
The 04 doesn't have fuel filters but I don't know about the 2006 models as you have. Definitely let us know what you found. It's always good to have a fuel pressure gauge in your toolbox at home as you can hook it up right there and get a running and a resting pressure meaning that if it drops and keeps dropping then more than likely you have a fuel line issue and depending on where you're at salt could or could not be affecting you.

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Thanks guys and Yes so it did relearn itself no engine light or anything really almost 200000 miles and she is running like a champ hopefully sometime this year I’ll be doing a cam and springs so I’ll probably  be adding another post with some more questions thanks again guys 

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