How do I tell when my ecu transitions from open loop to closed loop?
09-19-2012, 11:08 AM
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How do I tell when my ecu transitions from open loop to closed loop?
If I have my terminology correct, a cold engine runs in open loop, and when warmed up it runs in closed loop. How do I tell when (and if) it has switched from open to closed? Is it possible it could stay in open loop all the time without setting a code and turning on the CEL?
09-19-2012, 11:28 AM
#2
Re: How do I tell when my ecu transitions from open loop to closed loop?
How do I tell when (and if) it has switched from open to closed?
Is it possible it could stay in open loop all the time without setting a code and turning on the CEL?
09-19-2012, 12:09 PM
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Re: How do I tell when my ecu transitions from open loop to closed loop?
Sorry. 98 Civic EX 4-door sedan D16Y8 engine.
So if it MIGHT stay in open loop all the time, how do I tell which mode it is in at any given time?
So if it MIGHT stay in open loop all the time, how do I tell which mode it is in at any given time?
09-19-2012, 12:59 PM
#4
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Re: How do I tell when my ecu transitions from open loop to closed loop?
it prob would set off a cell after a start-up or two. Do you think its in closed loop all the time? bad fuel eco?
Coolant temp sensor is where id look first. find out its could voltage and its hot and Multi-meter it.
Will the idle change after it warms up?
Coolant temp sensor is where id look first. find out its could voltage and its hot and Multi-meter it.
Will the idle change after it warms up?
09-19-2012, 03:37 PM
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Re: How do I tell when my ecu transitions from open loop to closed loop?
I suspect it might be staying in open loop all the time, even after warmup. Idle does not change after warmup. Idle is appropriate for whatever temperature the engine is at startup, then stays at that RPM even after warmup. I have checked the coolant temp sensor with an ohmmeter and it is accurate per the graph in the shop manual. What I have NOT done is check the coolant temp sensor at the ECU.
So, is there a straightforward way without a ten-million-dollar scan tool, to tell which mode it is in?
So, is there a straightforward way without a ten-million-dollar scan tool, to tell which mode it is in?
09-19-2012, 03:55 PM
#6
Re: How do I tell when my ecu transitions from open loop to closed loop?
Why do you think your engine runs in open loop all the time?
It's most easily tested with a scan tool. I have an Actron CP9180 that reads live data, including whether the system is closed or open.
It's a pretty inexpensive purchase on eBay if purchased used:
http://www.ebay.com/sch/i.html?_trksid=p5197.m570.l1313&_nkw=CP9180&_sacat =0
It's most easily tested with a scan tool. I have an Actron CP9180 that reads live data, including whether the system is closed or open.
It's a pretty inexpensive purchase on eBay if purchased used:
http://www.ebay.com/sch/i.html?_trksid=p5197.m570.l1313&_nkw=CP9180&_sacat =0
09-19-2012, 05:12 PM
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Re: How do I tell when my ecu transitions from open loop to closed loop?
As THC07 asked, idle speed does not change after warm up, which led me to wonder if that could be a closed loop vs. open loop issue. I'm just theorizing, since I don't KNOW if that is how the Civic ecu would act.
Thanks for the recommendation on the Actron scan tool via eBay. It's time I bought some such tool, but I didn't want to lay out big bucks on it and obviously I want something that will be useful with my two Hondas.
Thanks for the recommendation on the Actron scan tool via eBay. It's time I bought some such tool, but I didn't want to lay out big bucks on it and obviously I want something that will be useful with my two Hondas.
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09-19-2012, 07:34 PM
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Re: How do I tell when my ecu transitions from open loop to closed loop?
closed loop fueling will use o2 sensor feedback to target stoich 14.7 AFR to acheive best fuel economy
After the transition to open loop is when the ECU uses known values +total corrections to establish its fueling.
So when your AFR is either 14.7 or the sensor voltage is consistent of stoich AFR you will then know that you are most likely in closed loop fueling. AFR's will richen up due to load increase, throttle, ect. When this occurs you can assume you have entered open loop fueling.
After the transition to open loop is when the ECU uses known values +total corrections to establish its fueling.
So when your AFR is either 14.7 or the sensor voltage is consistent of stoich AFR you will then know that you are most likely in closed loop fueling. AFR's will richen up due to load increase, throttle, ect. When this occurs you can assume you have entered open loop fueling.
09-19-2012, 07:43 PM
#11
Re: How do I tell when my ecu transitions from open loop to closed loop?
closed loop fueling will use o2 sensor feedback to target stoich 14.7 AFR to acheive best fuel economy
After the transition to open loop is when the ECU uses known values +total corrections to establish its fueling.
So when your AFR is either 14.7 or the sensor voltage is consistent of stoich AFR you will then know that you are most likely in closed loop fueling. AFR's will richen up due to load increase, throttle, ect. When this occurs you can assume you have entered open loop fueling.
After the transition to open loop is when the ECU uses known values +total corrections to establish its fueling.
So when your AFR is either 14.7 or the sensor voltage is consistent of stoich AFR you will then know that you are most likely in closed loop fueling. AFR's will richen up due to load increase, throttle, ect. When this occurs you can assume you have entered open loop fueling.
09-20-2012, 02:15 AM
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Re: How do I tell when my ecu transitions from open loop to closed loop?
RonJ, to answer your question, Yes, the dashboard gauge indicates proper temperature.
I was under the impression that once the engine warmed up, the ecu went to closed loop and stayed there. From what several of you are saying, it sounds like it can switch back and forth between the two modes even after warm up. Correct?
I was under the impression that once the engine warmed up, the ecu went to closed loop and stayed there. From what several of you are saying, it sounds like it can switch back and forth between the two modes even after warm up. Correct?
09-20-2012, 05:13 AM
#13
Re: How do I tell when my ecu transitions from open loop to closed loop?
RonJ, to answer your question, Yes, the dashboard gauge indicates proper temperature.
I was under the impression that once the engine warmed up, the ecu went to closed loop and stayed there. From what several of you are saying, it sounds like it can switch back and forth between the two modes even after warm up. Correct?
I was under the impression that once the engine warmed up, the ecu went to closed loop and stayed there. From what several of you are saying, it sounds like it can switch back and forth between the two modes even after warm up. Correct?
09-20-2012, 08:18 AM
#14
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Re: How do I tell when my ecu transitions from open loop to closed loop?
closed loop fueling will use o2 sensor feedback to target stoich 14.7 AFR to acheive best fuel economy
After the transition to open loop is when the ECU uses known values +total corrections to establish its fueling.
So when your AFR is either 14.7 or the sensor voltage is consistent of stoich AFR you will then know that you are most likely in closed loop fueling. AFR's will richen up due to load increase, throttle, ect. When this occurs you can assume you have entered open loop fueling.
After the transition to open loop is when the ECU uses known values +total corrections to establish its fueling.
So when your AFR is either 14.7 or the sensor voltage is consistent of stoich AFR you will then know that you are most likely in closed loop fueling. AFR's will richen up due to load increase, throttle, ect. When this occurs you can assume you have entered open loop fueling.
I dont even think a good scanner will show you anything accurate, even the live data scanners. Unless the OP had a Wideband im not sure if he could monitor this.
think all the scanner will do is say open or closed, back n forth back n forth with load changes.
09-20-2012, 08:52 AM
#15
09-20-2012, 08:58 AM
#16
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Re: How do I tell when my ecu transitions from open loop to closed loop?
No, not with any degree of accuracy.
If the car is in open loop all the time, you won't ever hear the idle drop to a lull rpm unless someone has tweaked the idle screw to make it idle normally. On cold starts, your car will rev up and gradually as it heats up, the idle will drop until the car reaches operating temperature and the idle will fall into its closed loop position and adjust itself by way of the 02 sensors. Until you're in closed loop, the car doesn't self-regulate with the 02 and can get bad gas mileage as a result.
The typical "performance" chip from eBay tricks your car into staying in open loop all the time. I dont know what is done to the car, but if someone else modified it, this could potentially be the culprit.
If the car is in open loop all the time, you won't ever hear the idle drop to a lull rpm unless someone has tweaked the idle screw to make it idle normally. On cold starts, your car will rev up and gradually as it heats up, the idle will drop until the car reaches operating temperature and the idle will fall into its closed loop position and adjust itself by way of the 02 sensors. Until you're in closed loop, the car doesn't self-regulate with the 02 and can get bad gas mileage as a result.
The typical "performance" chip from eBay tricks your car into staying in open loop all the time. I dont know what is done to the car, but if someone else modified it, this could potentially be the culprit.
09-20-2012, 05:07 PM
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03-20-2013, 01:13 AM
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Re: How do I tell when my ecu transitions from open loop to closed loop?
Have you checked the idle air control valve? I have a 98 hatch with a stock y8 swap. had a similar problem- no cel, ran like crap, poor fuel economy. Cleaned out the valve and ran waaay better
03-20-2013, 03:37 AM
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