Oepn/Closed loop
Thread Starter
Instructor
Joined: Sep 2002
Posts: 210
Likes: 0
From: Southfield Michigan
Oepn/Closed loop
At what temp does the computer change over from open to closed loop?
I recently did a EGR and while I was in there I changed the T-stat to a 165. My temps sometimes stay around 163-170 in the morning on my way to work. In the arternoon when it is warmer it is in the mid 180's. Before EGR/T-stat it was usually rock solid 210-215.
How cool is too cool? Also I heard temp can effect the MPG calcs? Is this something I should watch out for?
I recently did a EGR and while I was in there I changed the T-stat to a 165. My temps sometimes stay around 163-170 in the morning on my way to work. In the arternoon when it is warmer it is in the mid 180's. Before EGR/T-stat it was usually rock solid 210-215.
How cool is too cool? Also I heard temp can effect the MPG calcs? Is this something I should watch out for?
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: Oepn/Closed loop (BookSmart)
You coolant temp should be fine. What really effect the closed loop is a built in timer ~300 sec after startup, and then the sensor itself getting heated up. They are designed to work at a certain temperature, if they can't get hot enough they will stay stuck on a certain side of stoich, either rich or lean. Hence the reason why us guys with headers need to get heated ones. In most cases, it because your not driving the car around and the exhaust is not getting hot enough for the sensor to toggle or transition as its better know. The ecm should, if the transistions are low enough or few enough, set a trouble code.
Sounds to me like your fine and you shouldn't worry.
As for the MPG issue, never heard that before, but the only thing I could think of is running in a different heat range for the engine might effect efficiency. If you ask any of us racers, you will see us telling you that about 160-170 is best for performance. Past 200 performance usually dwindles away.
:cheers:
Sounds to me like your fine and you shouldn't worry.
As for the MPG issue, never heard that before, but the only thing I could think of is running in a different heat range for the engine might effect efficiency. If you ask any of us racers, you will see us telling you that about 160-170 is best for performance. Past 200 performance usually dwindles away.
:cheers:
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: Oepn/Closed loop (BookSmart)
You should go into closed loop when the oil-temp registers, like 150F.
While youre in open loop, the computer is richening the mixture to heat the engine up, and so the mpg drops. If you stay in open loop too long, your mpg really suffers.
Your temps sound like mine, you have nothing to worry about. But my mpg during the middle of winter can suck if i have to take alot of short trips.
While youre in open loop, the computer is richening the mixture to heat the engine up, and so the mpg drops. If you stay in open loop too long, your mpg really suffers.
Your temps sound like mine, you have nothing to worry about. But my mpg during the middle of winter can suck if i have to take alot of short trips.
Thread Starter
Instructor
Joined: Sep 2002
Posts: 210
Likes: 0
From: Southfield Michigan
Re: Oepn/Closed loop (vader86)
Thanks for all the info. I never really learned too much about fuel injection. More of a carb guy. Tho I did work on some fuel injection when I was a auto mechanic.
Yah I was VERY suprised when I seen my temps going down below 165. It was cool out but I figured the T-stat would keep it above that.
My EGR musta really been putting the hot gasses into the intake. Temps were usually 212ish no matter what, with a 195 stat.
Just installed some magna-flow cat back system. Car sounds nice and got rid of a LOT of resonance. Will be taking a long trip tomorrow and I will check out the MPG. My best on a long trip was 30, and usually around 28+. Will see tomorrow with new pipes T-stat and EGR if it goes up any. I am hopeing. I just LOVE teling people my vette gets 30MPG :eek: :cheers:
Thanks for the info :jester
Yah I was VERY suprised when I seen my temps going down below 165. It was cool out but I figured the T-stat would keep it above that.
My EGR musta really been putting the hot gasses into the intake. Temps were usually 212ish no matter what, with a 195 stat.
Just installed some magna-flow cat back system. Car sounds nice and got rid of a LOT of resonance. Will be taking a long trip tomorrow and I will check out the MPG. My best on a long trip was 30, and usually around 28+. Will see tomorrow with new pipes T-stat and EGR if it goes up any. I am hopeing. I just LOVE teling people my vette gets 30MPG :eek: :cheers:
Thanks for the info :jester
