2003 Avalanche stalls at low speed when firmly applying brake.

Hi there,
2003 Avalanche 191,000Kms 5.3L 4x4
When I am driving at low speed and lets say I turn sharply and apply the brake to enter a parking spot or to stop and back up, the vehicle will
stall. It will start up right away all the time after this happens. As well I notice that when I am at a stop light the truck will idle real low and the volt meter will go way down and the lights will dim until I step on the gas to accelerate. Same happens when I run the defroster or the A/C.
Any Ideas?
thx,
BG.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 7 Feb 2009 01:10:02 -0600, "Furnace"

Hi! It's a vacuum leak, most likely. Some times the vacuum hoses are cracked and they don't look like it; some times the oil fill cap is allowing air to be sucked in; some times the air intake hose (duct) is cracked and allowing air in. That is the "easiest" thing to check. If the hoses are good, it could be a stuck PCV (positive crankcase valve).
On my Toyota the air intake hose was split underneith where it was not visible, and the vehicle was doing exactly what you described above. I patched it with duct tape, bailing wire, and more duct tape because I'm poor white trailer trash, and it solved the problem.

--
http://desertphile.org
Desertphile's Desert Soliloquy. WARNING: view with plenty of water
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

That's unlikely to be the cause, vacuum leaks tend to increase the idle, not decrease it. This is more likely the cause....... http://www.automotivehelper.com/topic210522.htm Along with that, as a matter of course he should pull any stored codes with an OBDII reader and see what's there.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:


Uh, it is an obsewrved fact that a vacuum leak can cause low idle and stalling when the vehicle comes to rest.
Please do the following test: start your vehicle's engine (if you have one) and get it up to operating temperature; then unscrew the oil fill cap and remove it. Or disconnect the air intake hose.

--
http://desertphile.org
Desertphile's Desert Soliloquy. WARNING: view with plenty of water
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

An unusually high idle is indicative of a vacuum leak. This is pretty common knowledge....pull offyour PCV hose and see what happens if you don't believe me..
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:


Did you do the test I suggested? If you did you will have discovered the engine idle speed will decrease. This is also true for a bad air intake hose and other vacuum hoses.
--
http://desertphile.org
Desertphile's Desert Soliloquy. WARNING: view with plenty of water
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Did you do the test I suggested?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Did you do the test I suggested as well?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Not yet.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Dear idiot,
Giving people wrong advice is not doing them a favor.
--
http://desertphile.org
Desertphile's Desert Soliloquy. WARNING: view with plenty of water
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Then, of course, there's the type of idiot who thinks that an engine with a vacuum leak can only decreases the idle speed. http://www.aa1car.com/library/vacleak.htm http://www.thestar.com/Wheels/article/164073
And, of course, ignore the fact that I gave him what was likely the correct cause, a common issue with the throttle bore buildups. Plus checking for thrown codes with an OBDII scanner. I'd be looking for lean trim codes caused by unmetered air entry. So who's the idiot here?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Gentlemen, Gentlemen, play nice.
I removed the intake and noticed a considerable build up around the butterfly valve. I liberally sprayed Throttle Body Cleaner to remove the schmegma and whaddya' know.......... it worked. The truck idles fine and no longer sounds like it is going to die on me when the defroster kicks in.
Thanks for the advice.
BG.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Glad it worked out for you. Have a good one...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.