Lean at idle + IAC 0 = Intake Manifold leak?
05-18-2011, 12:29 PM
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Join Date: Mar 2005
Location: Vancouver, WA
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Lean at idle + IAC 0 = Intake Manifold leak? I took my car out of storage (and back from a family member) and am trying to work out all the bugs that a couple years of neglect cause.
Just to cover my bases:
Mods in sig.
MAF Cleaned (Reads 6-7gs at idle)
New 02 sensors (Bosch, sensor side harnesses lengthened)
New Plugs (NGK TR55 Platinums)
Plug wires not burned on headers
New Coolant temp sensors (both)
Headers checked for tightness
!EGR
!AIR
Desired idle set at 800.
The car idles/drives OK, but scanning shows idle BLMS were pegged at 160. I added 7% to the MAF calibration tables (descreened MAF was never accounted for in tune) which brought idle BLMS down to around 145-150. Once I did this my idle has risen to around 900-950 (still set at 800) and my IAC count has dropped to zero. IAC counts were 10-15 at idle before I did this.
Also when logging while driving, I have split BLMs, with the left side LTerm counts consistently 15 higher than the right side. BLMs are much closer (though still lean) at idle.
All of this says to me that I must have a leak on the driver side of the intake manifold. I have a gasket kit standing by but figured I'd verify before tearing things apart.
Thoughts?
Just to cover my bases:
Mods in sig.
MAF Cleaned (Reads 6-7gs at idle)
New 02 sensors (Bosch, sensor side harnesses lengthened)
New Plugs (NGK TR55 Platinums)
Plug wires not burned on headers
New Coolant temp sensors (both)
Headers checked for tightness
!EGR
!AIR
Desired idle set at 800.
The car idles/drives OK, but scanning shows idle BLMS were pegged at 160. I added 7% to the MAF calibration tables (descreened MAF was never accounted for in tune) which brought idle BLMS down to around 145-150. Once I did this my idle has risen to around 900-950 (still set at 800) and my IAC count has dropped to zero. IAC counts were 10-15 at idle before I did this.
Also when logging while driving, I have split BLMs, with the left side LTerm counts consistently 15 higher than the right side. BLMs are much closer (though still lean) at idle.
All of this says to me that I must have a leak on the driver side of the intake manifold. I have a gasket kit standing by but figured I'd verify before tearing things apart.
Thoughts?
