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Subject: "Need help... 4k idle on fresh rebuild!!" Previous topic | Next topic
infinite_420aJul-12-11 10:13 AM
Member since Jun 16th 2011
5 posts,
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#134582, "Need help... 4k idle on fresh rebuild!!"


          

Hey everyone i'm back on here after about five years. Couldn't find anything like this, let me start from the beginning... Hydro-locked, then rebuilt head, rebuilt engine with a 20-over bore, starts and runs great and timing is spot on. but i idle at 4000 rpm. when i put in gear it drops to 1500 or so. Any ideas for an old school 2gnt'er from the gurus??

95 NT AT
Bored 20 over, high flow oil
oversized SS EX. Valves P&P Head
... Finally back after after 5 years
and hydro lock

  

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Replies to this topic
RE: Need help... 4k idle on fresh rebuild!!, Moderatorteklein, Jul-12-11 10:16 AM, #1
RE: Need help... 4k idle on fresh rebuild!!, AdministratorCODE4, Jul-12-11 10:58 AM, #2
RE: Need help... 4k idle on fresh rebuild!!, infinite_420a, Jul-12-11 03:09 PM, #3
RE: Need help... 4k idle on fresh rebuild!!, AdministratorCODE4, Jul-12-11 03:18 PM, #4
      RE: Need help... 4k idle on fresh rebuild!!, 2ndGen-ElTalon, Jul-12-11 05:44 PM, #5
RE: Need help... 4k idle on fresh rebuild!!, Moderatorteklein, Jul-12-11 03:17 PM, #6

ModeratortekleinJul-12-11 10:16 AM
Member since Nov 04th 2007
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#134583, "RE: Need help... 4k idle on fresh rebuild!!"
In response to Reply # 0


          

My first thought is a IM gasket leak.

Second is TB gasket.

Third is stuck IAC pintle.

  

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AdministratorCODE4Jul-12-11 10:58 AM
Member since Nov 23rd 2003
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#134584, "RE: Need help... 4k idle on fresh rebuild!!"
In response to Reply # 0




          

Perform a boost leak test to find out where the leak is.

---

2012 2500HD LML


  

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infinite_420aJul-12-11 03:09 PM
Member since Jun 16th 2011
5 posts,
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#134585, "RE: Need help... 4k idle on fresh rebuild!!"
In response to Reply # 2


          

New intake gasket is on, tb is ok, will check the IAC, and maybe i might sound novice but never done boost leak test. Hows it done? cuz i usually just do sound and sight for air leaks.

95 NT AT
Bored 20 over, high flow oil
oversized SS EX. Valves P&P Head
... Finally back after after 5 years
and hydro lock

  

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AdministratorCODE4Jul-12-11 03:18 PM
Member since Nov 23rd 2003
2552 posts,
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#134587, "RE: Need help... 4k idle on fresh rebuild!!"
In response to Reply # 3
Jul-12-11 03:22 PM by CODE4



          

Just because the gaskets are new does not mean it is not leaking. Fuel injector o-rings can cause vac leaks as well.

There is plenty of information on how to do boost leak tests... http://www.google.com/search?q=boost%20leak%20test&ie=utf-8&oe=utf-8

Apply positive pressure to the intake side of the motor and listen for air escaping. To start, pop the intake piping off the throttle body, and with the motor running, seal the opening of the TB with your hand tightly. Listen for any hissing, as that is the only way your motor will be pulling any air at that point.

The concept is the same whether turbo'ed or not. Serves the same purpose.

---

2012 2500HD LML


  

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2ndGen-ElTalonJul-12-11 05:44 PM
Member since May 26th 2010
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#134588, "RE: Need help... 4k idle on fresh rebuild!!"
In response to Reply # 4


          

I'm with Tim & Dave, otherwise the last thing that comes to mind besides leaks, would be you're Throttle Cable. But after throughly rebuilding, I doubt you looked past something as simple as that.

Shot in the dark, but see if its adjusted properly. 2 bolts, easy, can't hurt to check simple things.

Jeff.

Originally posted by 740TurboBrick

"Dsms run on Gasoline, DSMers run on Alcohol...Id bring a tank to refuel the DSMers..."

  

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ModeratortekleinJul-12-11 03:17 PM
Member since Nov 04th 2007
1699 posts,
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#134586, "RE: Need help... 4k idle on fresh rebuild!!"
In response to Reply # 2


          

Originally posted by CODE4
Perform a boost leak test to find out where the leak is.


I dont think its a turbo.

  

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