TPI Runner Question

[timsiford at hushmail.com]

Wayne,

First, I am not the one here who is having this problem ... I am just lending 
some insight since I have experience with both systems.

However, although upgrading to the '89 code is a great solution, that route 
will not work.  The problem is that this guy has NO driver's side tube that 
connects the IAC to the air stream.  He installed 89+ runners on his pre 
'89 vehicle.  Basically, he is using a mismatched plenum/runner combo.  
Those pieces were never meant to work together and they will not work together 
regarding the IAC.  The '89 code is great.  But, it does not cure the fact 
that his IAC air has NO PATH to get into the air steam.  The IAC air on 
Pre '89 TPIs goes from the TB directly into the special passageway on the 
plenum.  This special passageway vents into the 'special' driver's side 
runner tube.  He is missing this tube.  This means that the IAC air is trapped 
in the passageway.  

Bruce - the TB's IAC outlet on pre '89 TPIs mates with the entrance to the 
'special' passageway of the plenum.  Thus, if you don't have the correct 
runner that mates with the plenum then the IAC does NOTHING because the 
IAC air has never gets into the incoming air.

Tim

Tim  


At Wed, 06 Dec 2000 14:19:12 -0500, "Wayne Johnson" <waynejohnson007 at hotmail.com> 
wrote:

>
>Tim,
>The 89's are MAF and they don't have the drivers side tube. Disable 
>the cold
>start injector and use 89 code. Forget about the holes in the lower 
>intake
>and IAC air, the 89 code will take care of it. It will work. :)
>
>Wayne
>
>
>>From: timsiford at hushmail.com
>>Reply-To: gmecm at diy-efi.org
>>To: gmecm at diy-efi.org
>>Subject: Re: TPI Runner Question
>>Date: Wed, 6 Dec 2000 13:42:16 -0500 (EST)
>>
>> >Wouldn't deletion of your coldstart valve avoid all that drilling?
>>
>>Nope.  Cold Start air if fed into the underneath of the plenum via 
>a
>>special
>>pasageway.  This pasageway feeds the driver's side 'special' runner 
>tube.
>>  If the 'special' runner tube is not present then the IAC air NEVER 
>gets
>>to the lower manifold.  He needs a way to vent the IAC air into the 
>air
>>stream.  In fact, I ran into a very similar problem a few weeks ago 
>when
>>I helped someone install new runners on their '87 Corvette.  He purchased
>>Hi-Flo runners that a guy had used on a '91 vette.  Well, the guy with 
>the
>>'91 vette had blocked off this tube extra tube on the driver's side 
>(and
>>rightfully so).  The guy with the '87 vette installed these runners 
>WITHOUT
>>unblocking the IAC tube.  Can you say hard starts and really rought 
>idle??
>>  We unblocked this tube and now all is AOK.
>>
>>Tim
>
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