[Syty] Passed emissions test, but why?

[DOlivares]

I AGREE about the temperature-floor being established by the T-stat, and that is why I was very careful to point out about AMBIENT temp (IAT input) being critical to getting into closed-loop operation... however it impacts the "jetting" and spark-advance curves implemented by the ECM.  I fondly remember my 160-equipped TTA jumping in and out of closed-loop during the Winter....  Glad to hear GM solved that problem with SyTys.

Being emisso-tested in the peak of Summer-- especially if you can run the A/C hard and then keep it on wile idling in line waiting for the tailpipe probe-- is also advantageous to passing with high scores because the stock radiator cannot dump the heat fast enough to get the water jacket down to the nominal rating-temp of the T-stat.

Nowdays-- since my exhaust "scoop" opened up the hood-- I can only get the Syclone to heat above my 180-mark when I'm idling above 95 with the A/C on.  This was quite a chore in my TTA which was obviously over-capacity in cooling compared to the Sy....

D.O.
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----- Original Message ----- 
From: Jim Sloan 
To: 'DOlivares' ; RadarBlueTyphoon at aol.com 
Cc: syty at syty.org 
Sent: Thursday, January 19, 2006 7:02 AM
Subject: RE: [Syty] Passed emissions test, but why?


Detailed information on closed loop and cold operation can be found at http://sunflower.com/~leroy/P4/section9.htm , if you are interested.  It should be in closed loop and out of cold operation at 160.

I don't think it really explains why some pass and some fail emissions with a 160 thermostat, though.  I have a theory to toss out there.  Toss it back if you don't like it.  The thermostat sets the minimum cooling system temperature.  Maximum cooling temperature is determined more by the radiator, and overall condition of the cooling system.  For example, I have a 160 thermostat, but often see temperatures close to 180 (and I think my cooling system is in pretty good shape).

Another factor to consider is the intercooler pump.  It's not set to come on until around 180, and it's operation would affect the MAT.  A failing  IC pump may help emissions.

Jim



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  From: syty-bounces at syty.org [mailto:syty-bounces at syty.org] On Behalf Of DOlivares
  Sent: Wednesday, January 18, 2006 9:24 PM
  To: RadarBlueTyphoon at aol.com
  Cc: syty at syty.org
  Subject: Re: [Syty] Passed emissions test, but why?
  Importance: Low


  It's obviously 'cause, as I plainly said, the ECM algorithms of the SyTys apparently don't correlate IAT & CTS inputs in such a way as to prevent the System from going into closed-loop operation... probably after a fixed amount of TIME or other variable.  I "explain" it by the absence of commentary or notices to the contrary.

  And even though you may have passed emissions-- possibly with a "gentlemen's C"-- with that colder-than-stock unit, I think you might well have ace'd the test with a hotter 'stat!

  Never having HAD to worry about emissions blues with either my 'Phoon or my 'Clone (which also came with a 160° t-stat but which I changed to a 180° right away as part of the underdrive-pulley installation... to facilitate drivability, increase the lousy mileage, and keep my tootsies warm in that Northern climate), I just never got into the finagling I did with the TTA.  Then I leapfrogged to the 10-in-1 a year later and left my SyTy-chip-reprogramming activities on the Bench for a rainy day....

  Okay? 
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  ----- Original Message ----- 
  From: RadarBlueTyphoon at aol.com 
  To: seravilo at netzero.net 
  Sent: Wednesday, January 18, 2006 8:04 PM
  Subject: Re: [Syty] Passed emissions test, but why?


  Well Dennis maybe you can explain this one for him. The Ty  you purchased from me has run an 160 thermostat since I purchased it and it never failed an emission test her in St. Louis.

  Tim
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