Time from open loop to closed loop...

[BamZipPow]

Have any of you timed that? How long does it take fer yer vehicle to go from open to closed when yer starting yer vehicle fer the first time of the day?

I've been checking mine lately just out of curiousity and it seems to take about a minute. Ambient temps don't seem to affect the time (32° to 60°F) as far as I can tell.

I've been checking it with my Scangauge II...

[cfg83]

BamZipPow -

I see about a minute too :

http://www.youtube.com/watch?v=CZ9G_h5o2Yc

I switched from a non-heated to a heated-02 sensor. The amount of time doesn't change, but I can at least *see* what the AFR is doing while the engine is warming up :

Using heated 02 sensor in place of non-heated 02 sensor

CarloSW2

[thatguitarguy]

Will it still take a minute if you have to turn you key to start the car at the end of an EOC?

[cfg83]

thatguitarguy -

Originally Posted by thatguitarguy

Will it still take a minute if you have to turn you key to start the car at the end of an EOC?

No. Once the engine is warm it takes less than 10 seconds. Sometimes less than 5. I think it goes to closed loop fast when the engine is warm. The ECU/PCM probably looks at the coolant temperature.

If closed loop does look at the coolant temperature, you could probably fool the ECU/PCM into faster closed loop operation by spoofing the coolant temperature sensor. The bad thing about this is the implication (but not the fact) that you could hurt your engine at warm-up. I think you would definitely harm your emissions.

CarloSW2

[BamZipPow]

Well...found out something interesting today.

After a quick minute warm-up this morning...I made my standard runs in closed loop. After the truck sat fer about an hour, starting coolant temp was at 146°F. Started the truck up and waited fer it to go to closed loop. About 4 minutes later, it finally went to closed loop. Coolant temp had risen to 188°F. Ambient air temp was about 45°F. What gives? My normal coolant temp is about 206°F.

I also noticed that when I coast, it registers as open loop when the injectors cut off. Hmmm...

[mwebb]

..."
I also noticed that when I coast, it registers as open loop when the injectors cut off. Hmmm... "...

when the injectors are "cut off"
you are probably not coasting in neutral -

when MR ECM sees throttle closed and engine rpm above around 1200 rpm , MR ECM shuts off the fuel
that condition is known as
"Decel Fuel Cutoff"

it will / should not happen at idle when coasting in neutral

"Decel Fuel Cutoff" should happen when traveling down hill in gear with the throttle closed , engine rpm over around 1200 rpm

since the feed back system for controlling mixture is disabled during
"Decel Fuel Cutoff"
the system should be in open loop
other wise
MR ECM would see 02 sensor pinned lean and MR ECM would do everything it could to make the mixture rich enough to get the 02 sensor to start cycling
since fuel would be disabled due to "Decel Fuel Cutoff"

there would be an unresolvable conflict .

[cfg83]

BamZipPow -

Originally Posted by BamZipPow

Well...found out something interesting today.

After a quick minute warm-up this morning...I made my standard runs in closed loop. After the truck sat fer about an hour, starting coolant temp was at 146°F. Started the truck up and waited fer it to go to closed loop. About 4 minutes later, it finally went to closed loop. Coolant temp had risen to 188°F. Ambient air temp was about 45°F. What gives? My normal coolant temp is about 206°F.

I also noticed that when I coast, it registers as open loop when the injectors cut off. Hmmm...

Arghhhh. Everything I am telling you is how my car works. It looks like your ECU/PCM behaves differently.

Let's look at it from a different POV. As a programmer, I might make the decision to *report* open-loop condition when I turn off the fuel injectors. Why? Because when I turn off the fuel injectors, the 02 sensor is not being used to control the fuel injectors. I am not *in* closed-loop operation.

In my 1999 Saturn SW2, this is what I observe :

1 - Coasting downhill in gear. Engine stays *above* 2500 RPM because of slope of hill.
2 - Scangauge continues to report Closed Loop
3 - Digital AFR shows Lean condition, proving DFCO

In this instance, maybe the programmer said, yes, I know I have turned off the injectors, but I also *know* that the ECU/PCM is still in control, so I will continue to report closed-loop.

Regarding 4 minutes to closed loop, I haven't seen that. I have a mild climate, so it is easier for my car. But 4 minutes? With a warm engine? I *want* to say failing 02 sensor, but I really have no idea.

CarloSW2

[RobertSmalls]

My Subaru took several minutes - maybe four. The Honda does it in very fast. I think it's much less than a minute but I've never bothered to watch carefully.