[Gmecm] TBI and EFE

[David Allen]

  Made absolutely no noticable difference on my TBI-equipped 305.  Re-designing the snorkel to have a larger inlet, and switching to a taller A/F element made a great improvement in high RPM power.  The idling and starting was uneffected.
  Car has been run in Minnesota in February without problems.  The ECM has an air temp sensor in the air box and it seems to do quite well at compensating for the cold-air intake.
   Good luck,
David



----- Original Message ----- 
From: "Jared Ryan" <jryan at caminofx.org>
To: <gmecm at diy-efi.org>
Sent: Friday, December 01, 2006 12:28 PM
Subject: [Gmecm] TBI and EFE


> Do TBI engines typically need the EFE ThermAC setup to run smoothly in 
> cold weather?
> 
> I have an El Camino that has a heat stove on the passenger side, but I 
> recently changed to a Camaro air cleaner that puts the snorkel on the 
> driver side (this fits MUCH better with my Camaro serpentine belt setup). 
> I will need to put a heat stove on the left-side exhaust manifold in order 
> to use the ThermAC.
> 
> I assume it wouldn't be there (on '88-'92 TBI F-bodies) if it didn't help. 
> It made a BIG difference in cold-weather running when I had the QuadraJet 
> carburetor, and TBI is also a wet-manifold system.
> 
> The reason I ask is that the temperature has dropped into the 30s F, which 
> is cold for Houston, TX, and the idle is a little rough.  However, the 
> cold weather moved in on the same day I removed and cleaned the IAC valve. 
> It is entirely possible I just need to reset the minimum-air setting and 
> the idle will smooth out.
> 
> Off-idle performance has been perfect, just a little bit of a rough idle 
> since it turned cold.  I will do the IAC reset this afternoon, but I still 
> wonder if making the ThermAC operational will help a lot.
> 
> I notice that the TBI intake manifolds no longer have the exhaust 
> crossover under the carburetor/throttle body mounting pad.
> 
> I hear a lot about ThermAC, like "It only closes in *really* cold weather. 
> When I had it set up properly with the QuadraJet, it would close at least 
> a little bit on sunny warm spring days!  It would open quickly, but it 
> didn't only work on very cold days, for sure.  On very cold days, like 
> what we have here, it often wouldn't ever open completely.
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