Open Loop vs Closed loop ?

cujotom · 05-10-2006, 12:27 PM

On my 94 2.2 Cavalier RS How can I be sure that my car changes over to closed loop, where I know that instead of running off of default values that i actually know that its looking at the sensors values ? Tom

94VL · 05-10-2006, 05:16 PM

It goes into closed loop after a couple minutes,or when the temperature reaches a certain point.If something is keeping it from going to closed loop,the check engine light will come on.

cujotom · 05-11-2006, 08:49 AM

Would that be the temp off the coolant temp sensor? Or the o2 sensor ,or both. If its off the CTS would it make that big of a diffrence If I put in a 180F thermostat instead of the 192F or the 195F. What temp would it change at?

ford460bigblock · 05-11-2006, 12:41 PM

if it was running only in open loop u would have bad gas mileg also in open loop the pcm does not playatension to the o2 sensor but it will take inputs for all the other sensers

94VL · 05-11-2006, 05:25 PM

This is why some things like thermostats should not deviate from factory recommendation.Just because they sell 160 and 170 and 180 degree thermostats doesnt mean you can just drop them in and it wont have any other side-effects.Basically,if you split hairs,doing anything to defeat the oem emissions hardware (and thus create more pollution) is illegal.Its called tampering.This is why back in 1976,the Feds wanted to make car's underhood areas accessable only thru dealers with a special tool that could remove the front bodywork (they even were talking about NO removable access to drivetrains....making them factory sealed).We can all be thankful that the fat-cats never got what they really wanted.....

cujotom · 05-12-2006, 07:30 AM

94Vl,
For the record, the only reason that I wanted to go to a slightly cooler thermostat was very simply for the summer months for the engine to run a bit cooler. Period, Not to screw with emissions or emission Tampering! Really if I wanted to do that I would have gotten rid of all the smog equiptment. Starting with the cat and working my way forward... I do know what is legal and what is not. I mean I am the kind of guy that went out and just spent around $70 for a new EGR valve as the Diaphram was sticking... I could have just blocked the hose and been done with it. Most people in there right minds would have just bypassed instead of spending that kind of money on a car that is rusting with over 160,000 miles on it. In reading your past posts its very clear that you are a stickler on being legal etc, not that thats a bad thing, I just didnt remember If I asked you what was legal and what wasnt. Some might think that you come off with a holier than though attitude... Not Trying To Start an Argument. I am very sure most people know that its straight up wrong to want to gut a cat, or just take it off. They ask, regardless of the fact of its legality... You sound like a smart guy, lighten up a bit...

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