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Closed loop,fan turn on,& thermostat

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Old Oct 30, 2003 | 06:12 AM
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Default Closed loop,fan turn on,& thermostat

What temp does the computer go into closed loop? If I lower the fan turn on to 160 and put in a 160 thermostat, will it ever go into closed loop? Is there a way to change when it goes into closed loop, or should I go with more like 180 deg setup.
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Old Dec 21, 2003 | 05:30 PM
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Originally Posted by Ventura
What temp does the computer go into closed loop? If I lower the fan turn on to 160 and put in a 160 thermostat, will it ever go into closed loop? Is there a way to change when it goes into closed loop, or should I go with more like 180 deg setup.
id like to see a reply on this
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Old Dec 21, 2003 | 06:01 PM
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me also..
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Old Dec 22, 2003 | 09:11 PM
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most engines wait for a valid signal then go into closed loop, but this doesnt mean the enrichment is gone. The ls1 edit folks might be able to clue us in.

There's no reason to not go to closed loop once the o2's are up to temp and feeding good signal, but if you got the cold start enrichment at that temp it might make things funky for a bit.

Since i dont know ls1 tuning (i do vag) im curious if theres a FE table for cold start so you can drop it at 160 instead of (stock). cause i dont want to be in cold start mode when its not necessary. I actually hacked out the cold start FE under boost (VAG) at all temps cause it would cause unnecessarily rich conditions when cold (yah yah no boosting when cold) but the motor being cold was able to extract the higher egt's more easily with more timing and no KR.

I guess the secrets of the ls1 ecu are still pretty tightly wrapped up?
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Old Dec 26, 2003 | 06:40 PM
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I don't know exactly where the closed loop ECT threshold,
but I can tell you the Hypertech 160 thermostat really
holds the water jacket at about 175F (+/-3ish) and this
has no effect on my car going into closed loop. I recall
watching with the Predator and seeing stuff start happening
with the STFTs at about 140F. But whether this is the floor
or not, couldn't say for sure.

But the nut of it it, the Hypertech 160 is not a problem.
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Old Dec 27, 2003 | 09:48 AM
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Originally Posted by Ventura
What temp does the computer go into closed loop?
I am still unclear on the closed loop.... what exactly happens when it goes into closed loop? It reads the O2 sensors and emissions equipment when this happens? I would think more than this.... If you keep it out of closed loop will the car run poorly, even if tuned correctly? I saw a post that said something about the Fuel/Air multiplier table in LS1 Edit being where the car gets it's 'directions' from when not in closed loop... If anyone can clarify some of these questions for me it would be very cool of you!

HAPPY HOLIDAYS and HAPPY NEW YEAR guys!
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Old Dec 27, 2003 | 06:50 PM
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being in open loop with a mass air flow can be fine, if its tuned and stays within that tuned condition. There's also the map sensor that can be used i spose too.

I would still like to know if there is a table that adds fuel enrichments based on temps.

Would suck to have 160 thermo and be stuck in cold enrichment mode.

Some ecu's can have both, closed loop o2 mode with cold start enrichments, to reduce emissions, but running too cold temps would result in crappier target air fuel since the motor thinks its still doing its warmup biz.

All that cold start enrichment b/s ends up throwing extra fuel in that pollutes your oil. If you are like me, i drive 2 miles to work, in winter thats like 80% of the trip below the thresold of full op temps. Im curious if the tuners tweak this so i dont end up changing oil every 300 miles (or 2 months). Gassy oil sucks, go sniff your dipstick lol sometimes if you think you are running too cold. Smell gas? Change the oil.
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Old Dec 28, 2003 | 10:30 PM
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Originally Posted by Ventura
What temp does the computer go into closed loop? If I lower the fan turn on to 160 and put in a 160 thermostat, will it ever go into closed loop? Is there a way to change when it goes into closed loop, or should I go with more like 180 deg setup.
The info below is from a Corvette Engine management book by Charles Probst. A must read for all LS1 engine owners.
Attached Thumbnails Closed loop,fan turn on,& thermostat-ectclosedloopsmall.jpg   Closed loop,fan turn on,& thermostat-bookcover.jpg  
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