High Idle on my 2000 5.3

[Bigntall1]

Hi everyone. I am a newbie to this site. I am a member at Tahoeforum but it was suggested to me by Shaggy that I become a member here due to the lack of activity over there. I have a 2000 Tahoe NBS 2WD LT 5.3 that's my wife daily vehicle. Recently it was having an issue with losing about an inch of coolant every 2 to 3 weeks. Took it to my shop auto repair location and they told me that it was the water pump. Wasn't going to spend $350 - $400 letting them do it so I bought one and install it without any issues. That was last wednesday. So far the levels are still good and no warning on the display console. When I was driving it the other day I noticed after I stopped and put it in park the engine idled fine for a couple seconds then it staring idling high. Maybe a little over 1k RPMs. When I put it in gear it idles fine. I ask my wife how long this has been occuring and she said for a while now and that she told me about it before. I seached this site to see if anyone else was having the same issues and I found a lot of 99 and under owners who've had the problem. Most of their issues was the result of a leaking intake or head gasket if I remember correctly. My question is has any 00 - 06 owners experienced this? I have the shop do another pressure test. It has approx 138k miles on it.

Thanks in advance.
Greg

 

[Narco]

you should prob post this in the main general area...this section is for tech write ups and how to's. you might have better luck finding help there.

 

[blueflamed03]

vacuum leak?

 

[Mr45]

vacuum leak?

This.

 

[Bigntall1]

you should prob post this in the main general area...this section is for tech write ups and how to's. you might have better luck finding help there.

Thanks! I wasn't sure If I was in the right section but it was the only one that had any reference to Tech questions. Would the moderators get upset with me if I posted the same topic in the General section? Don't want to double post.

---------- Post added at 06:41 AM ---------- Previous post was at 06:40 AM ----------

vacuum leak?

Will a pressure test or some other test confirm this? Is it serious and how much will it cost me to fix?

---------- Post added at 06:44 AM ---------- Previous post was at 06:41 AM ----------

I see someone has moved this to the right section for me. Thanks!

 

[blueflamed03]

a dealer might be able to detect where/if there is one, a small leak could cause a high idle to compensate.

 

[Bigntall1]

Ok thanks. I'll have it tested next week.

 

[badtothe bone]

There is a simple test to check the condition of the intake gaskets and it only costs a couple of dollars and it does the same thing as a expensive test at the dealer.

Park it outside and start it up and spray some WD 40 around the gaskets and see if it accelerates when you spray it around the intake manifold. If you can find the exact spot where it is leaking, that would help.

My experience with that series of engine tells me that you could also have a problem with the plastic intake manifold - where it is cracked.

The intake manifold in torqued in INCH POUNDS - not foot pounds.

The Intake Manifold gaskets have been known to leak. But at the same time, there is no water directly flowing between the heads or inside of the intake manifold, so there is no real reason for the intake to be torqued all that tight and a simple application of RVT would probably seal most any leak.

Because the intake is plastic, it is harder to diagnose, due to the fact that you cannot magnaflux plasticl

There is a series of hoses on top of the intake manifold that could leak. There is a number of modules on top of the intake manifold that could leak.

One of my first questions to you is how well do you maintain the vehicle?

Most people understands Points, plugs and condenser, but they don't understand fuel injection. Have to ever taken off the hose that goes to the mass airflow sensor. Have you ever cleaned the mass airflow sensor?
How often do you clean it?

 

[Bigntall1]

There is a simple test to check the condition of the intake gaskets and it only costs a couple of dollars and it does the same thing as a expensive test at the dealer.

Park it outside and start it up and spray some WD 40 around the gaskets and see if it accelerates when you spray it around the intake manifold. If you can find the exact spot where it is leaking, that would help.

My experience with that series of engine tells me that you could also have a problem with the plastic intake manifold - where it is cracked.

The intake manifold in torqued in INCH POUNDS - not foot pounds.

The Intake Manifold gaskets have been known to leak. But at the same time, there is no water directly flowing between the heads or inside of the intake manifold, so there is no real reason for the intake to be torqued all that tight and a simple application of RVT would probably seal most any leak.

Because the intake is plastic, it is harder to diagnose, due to the fact that you cannot magnaflux plasticl

There is a series of hoses on top of the intake manifold that could leak. There is a number of modules on top of the intake manifold that could leak.

One of my first questions to you is how well do you maintain the vehicle?

Most people understands Points, plugs and condenser, but they don't understand fuel injection. Have to ever taken off the hose that goes to the mass airflow sensor. Have you ever cleaned the mass airflow sensor?
How often do you clean it?

Thanks for the information. I maintain them to the best of my mechanical knowledge. Oil changes, fluid levels, brakes, etc. When it starts to sound strange or not run right then I have a professional look at it and tell me the problem. My dad is a good mechanic so most of the time I let them diagnose the problem and I save money by buying the part and having it installed or repaired myself. I can't say that I've ever cleaned the Mass airflow sensor. I bought the vehicle at 63k miles from my father and I'm not sure if he's ever did it either.