Low temp thermostat

[Mark Romans]

Hi Tyler:  Check out this page,  it explains a lot about the operation of
the ecm on a turbo buick.  Most of the stuff applies to all GM ecm's.

http://www.thrasher-ep.com/cal_hints.htm

By the way, when the coolant temp goes too low the engine goes out of closed
loop and into open loop.  (It is then ignoring the 02 sensor).

Mark

-----Original Message-----
From: Tyler Townsley <ttownsley at sprynet.com>
To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
Date: Tuesday, October 26, 1999 9:46 PM
Subject: Re: Low temp thermostat


>It depends on the engine.  Spend some money on Dyno time.  IE put the
>car on a dyno and do some runs at the temps you feel happy with and see
>what happens to rwhp.  A local shop owner who has a 91 Corvette zr1 ran
>extensive tests with his own car and found that the LT 5 engine likes
>the cold (It was designed in England) max HP was at 159 deg water temp
>as indicated on the DIC.  The HP fell off quickly for the next 15 or 20
>degrees above that (don't remember the numbers as this was several years
>ago.)  I had a chance to talk to several engineers involved in the
>design and testing of said engine and they confirmed that the
>operational temperatures were an Emissions issue rather than a
>performance issue and saw no real long term durability problems in
>running the LT 5 engine in the 160 to 165 water temp range but the
>cautioned that it goes closed loop? if it gets below 154 degrees.  I run
>mine with open thermostat, aftermarket radiator and fan switches and see
>160 deg temps in summer Fla heat on the interstate with 190 or so in
>town temps.  Engine has 140,000 mi total with a broken valve spring
>rebuild at 67,000 mi. currently has 400+ rwhp (LPE rebuild several years
>ago).  I run it hard, drive it every day and have no complaints in the
>durability area.  Oh yea anyone ever try to diagnose a broken valve
>spring on a quad cam motor? It aint easy.
>
>Tyler Townsley
>PS Hoping to learn how to program the chip, a lot of what you guys say
>is over my head but I keep on learning.
>