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Discussion Starter #1 (Edited)
Problem with Open Loop Mode (1.8 16V Petrol)

Hello Guys!

I have a Peugeot 406 1.8 16V (XU7JP4, Bosch MP7.3)

I have an issue regarding Open Loop Mode.

When i analyzed the car with PP2000, i noticed that it always remains in Open Loop (even when coolant temperature is above 90 degrees celsius).

I mean "Richness Regulation Status" is always reading Open Loop.

I checked Upstream O2 Sensor and it works fine and fluctuates rapidly.

I also checked Coolant Temp. Sensor and it runs without any problems and reports correct temperature.

Also my car didn't have any fault codes relating to Rich Mixture Condition.

My gas mileage is not bad and i don't have any power/acceleration issues either.

I know that when engine warms up it should go into Close Loop Mode but that doesn't happen in my car.

I even checked spark plugs and they didn't contain any black soot related to rich running operation. They were just fine.

So, what is the matter with my car?

Thanks in advance.
 

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So, what is the matter with my car?
What from you've posted, nothing. You say it runs fine, does the expected mpg, performs acceptably. Having diagnostics to hand can be a double edged sword.
My previous 407 had fault codes about the wing mirrors and door modules, yet everything worked as it should so I didn't worry.
 

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Discussion Starter #3
What from you've posted, nothing. You say it runs fine, does the expected mpg, performs acceptably. Having diagnostics to hand can be a double edged sword.
My previous 407 had fault codes about the wing mirrors and door modules, yet everything worked as it should so I didn't worry.

Thanks for your answer!

So, you think PP2000 is telling me incorrect information about Loop Mode?

It is strange that everything is fine but ECU doesn't go into Close Loop Operation!

I know that the car runs like a charm and i enjoy it but i am afraid that maybe there is a problem which will show itself in the future and i just want to be on the safe side!
 

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Check parameters in Planet maybe throttle position is not showing 0%/closed throttle so ECU thinks car is still on overrun and therefore open loop. if you hold RPM around 1500-1750 does car go closed loop
 

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Discussion Starter #5
Check parameters in Planet maybe throttle position is not showing 0%/closed throttle so ECU thinks car is still on overrun and therefore open loop. if you hold RPM around 1500-1750 does car go closed loop
So, you suggest that i fiddle with throttle position to be able to see Closed Loop on the screen?
 

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I may be totally off the mark with this idea but usually 'open loop' or 'closed loop' refers to the method of feedback that is used. If it does refer to the feedback method then it will be one or the other - never will it be both. The feedback method will not change. If this is the case then there is nothing wrong.
 

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I was suggesting a possible reason for your open loop If car passes MOT with no issues then you can leave alone.
 

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Discussion Starter #8 (Edited)
I also checked Throttle Position and it was correct!

When idling it was 0% / Closed Throttle.




So, it seems that my TPS is working as it should.


If it does refer to the feedback method then it will be one or the other - never will it be both
It depends on driving conditions. If you are cruising it should be in Closed Loop and @ WOT it should be in Open Loop.
 

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It depends on driving conditions. If you are cruising it should be in Closed Loop and @ WOT it should be in Open Loop.
You seem to have misunderstood my meaning. A feedback circuit will use either a closed loop or an open loop system. I've never come across a feedback circuit that switches between the two. If is does change from open to closed than it won't be referring to a feedback system. I've never come across a references to open or closed loop when I've done diagnostics - just references to open circuit or short circuit. In fact the oly time I have seen reference to open or closed loops is in a description of feedback circuits as is described here. As it explains, something that is closed loop can not in normal operation be open loop. If it's sensor has failed it would work as an open loop circuit but that wouldn't be normal operation.

As I said - I may be way off the mark but that is what open / closed loop means to me and the rest of the electronics industry. Then again it may just be a misinterpretation in the translation from the French original and mean something totally different
 

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As far as i know, speaking about cars, Open Loop and Closed Loop are two different ECU modes and not circuits or sensors.

How to Tune Closed Loop and Open Loop o2
Well as I said - I may be well off the mark. My response was purely about the feedback system and not about whether the ecu was using it or not. The article you linked to was an interesting read and confirms what I said BUT explains that the ECU can either use the sensor information or ignore it. I misunderstood the reference to open or closed loop in your original post. I thought you were refering to the feedback circuit itself changing from open loop to closed loop rather than the ecu mode changing
 
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