THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

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lancia58
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by lancia58 »

As long as I remember the HPFP pressure is 40 bar . The high pressure fuel pump is new .The Diagbox doesn't have a set-point for the fuel pressure. Just live readings



Zohar
igorkukarin
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by igorkukarin »

Hello, Zohar,

could you share please, how the story with p2177 ended? How did you solve it?
I have p2177 now, the symptoms are the same
lancia58
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by lancia58 »

Hello Igor,

Unfortunately that story didn't end. It appears from time to time. When it appears I clear it and the turbo is back to life. The P2177 triggers only when the car stops ( 0 Kmh ) . I recorded the Lexia fault log and cannot find something in common for the fault appearances but the fact that it triggers at 0 Kmh. The check engine does not lit each time the ECU put the turbo in limp mode. If the car is driven for a long time with the turbo in limp mode the check engine will lit. I recall that all started after the high pressure fuel pump was replaced. A friend of mine who is a mechanic did the job. After he did the job he insist in washing the engine with a hose and since then I think the problem started. I think that since then maybe one of the sensors does not functioning well. I guess I will have to take the car to authorized garage although I not sure they will sort it. If you find the cause let me know. If I'll sort it I'll post the solution here

Good luck
Zohar
lancia58
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by lancia58 »

Hello Igor

Did you find the cause for the p2177
lancia58
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by lancia58 »

Hi

The P2177 error was never resolved , when it happens I just clear it. I want to resolve it. The only thing I know for sure it happens when the car if fully stopped ( 0 KM/h ) i.e. when in idle. I think that fact indicates that it is not injectors, not the MAF sensor nor vacuum leak.The only thing I can think of is that may be the air intake throttle is not completely closed when in idle or not closed enough. I did notice that sometimes when turn on the engine it is rough a bit at Idle. I do not know if the throttle can be adjusted with a Lexia. Anybody has an Idea ?

Thanks
lancia58
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by lancia58 »

Hi

I drove the car while the Lexia is hooked and looked if one of the parameters measured by the Lexia is not match the required setting parameter. At he air inlet section there is a parameter "Air flow" and "Air flow setting" . The setting means the expected air flow. The measured "air flow" was always different by a large margin from the "Air flow setting" . I looked at all other parameters with setting values and the measured ones were very close to the setting values. I guess that this is a problem. I think it can be a reason of two factors. First the air flow sensor is faulty or a sensor the ECU uses to calculate the required Air flow is faulty. By the way what is the sensor that measures the air flow ?

Thanks
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xantia_v6
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by xantia_v6 »

There is no air flow sensor on the turbocharged EP6 engines. Air flow is calculated from the pressure and temperature measured at the MAP sensors. The calculation is affected by the columetric efficiency of the engine, and is thus wrong if the valve timing has moved from the correct setting.
lancia58
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by lancia58 »

When you say valve timing you mean the piston valve ? The timing gear was changed 2 years ago and the car has done 10,000 KM since then. Changing the timing didn't sort the problem. Can you please elaborate a bit in the linkage between the calculated air flow and the valve timing ?

Thanks
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by xantia_v6 »

The engine ECU controls the amount of fuel injected into the cylinders to keep the mixture ratio correct. To do this is must estimate the mass of air drawn into the cylinders.

If you think of the intake side of the engine as a pump, if there were no restrictions on the air flow (and no turbo boost), every 2 crankshaft revolutions a 1.6 litre engine would pump 1.6 litres of air and would have 100% volumetric efficiency. Putting restrictions in the intake (such as a throttle butterfly) reduces the volumetric efficiency because the engine can't pump as much air per revolution, and the MAP sensor is used to enable the ECU to calculate the reduced volumetric efficiency and thus the reduced airflow.

If the valve timing is changed from the designed angles, the volumetric efficiency is also changed (usually reduced), but the MAP sensor cannot correct for this, and the calculated fuel ratio will be wrong. The Oxygen sensor feedback loop can correct this up to a point, but there are limits to how much correction is allowed.
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by GiveMeABreak »

To avoid any possible confusion, I think Zohar (Lancia58) is getting the engines mixed up - please confirm if this is not the case though.

If this post you started is referring to your 2009 C4 2.0i 16V 180, then it's not a THP Prince Engine and this can be misleading for others. If this is for your C4 180 then you have the EW10J4S engine which is completely different.....

Can you please confirm so I can amend the Topic title, so as not to confuse contributors who think this is a THP engine you are referring to.....
lancia58
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by lancia58 »

I have two C4s one with the 16V 180 and one with the THP prince engine. The P2177 is related to the THP prince engine.
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by GiveMeABreak »

Ok, thanks for clarifying Zohar, I think I have found reference to a C4 1.6 THP 16V 150 (EP6DT) 4-speed Auto now from your previous posts. Might be worth updating your profile to list your car models. :wink:
lancia58
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by lancia58 »

xantia_v6 wrote:
08 Aug 2020, 11:19
The engine ECU controls the amount of fuel injected into the cylinders to keep the mixture ratio correct. To do this is must estimate the mass of air drawn into the cylinders.

If you think of the intake side of the engine as a pump, if there were no restrictions on the air flow (and no turbo boost), every 2 crankshaft revolutions a 1.6 litre engine would pump 1.6 litres of air and would have 100% volumetric efficiency. Putting restrictions in the intake (such as a throttle butterfly) reduces the volumetric efficiency because the engine can't pump as much air per revolution, and the MAP sensor is used to enable the ECU to calculate the reduced volumetric efficiency and thus the reduced airflow.

If the valve timing is changed from the designed angles, the volumetric efficiency is also changed (usually reduced), but the MAP sensor cannot correct for this, and the calculated fuel ratio will be wrong. The Oxygen sensor feedback loop can correct this up to a point, but there are limits to how much correction is allowed.
But if the ECU gets the correct air flow from the MAP sensor ( air flow depends on the valve angles as well ? ) it can inject the correct amount of fuel to maintain the fuel/air ratio ? By the way there is a parameter called "inlet camshaft dephaser position" and it the same as the "inlet camshaft dephaser position setting" , isn't that an indication that the timing is set correctly ?

Thanks
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xantia_v6
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by xantia_v6 »

The MAP sensor does not measure airflow, the P stands for Pressure. There is no airflow sensor.
The engine has no sensor that measures the actual valve timing, the ECU calculates it from what it has requested of the actuator, on the assumption that the static timing is exactly correct. The static timing will not be correct if the timing chain has stretched, of if there has been any slippage of the timing sprockets (which unfortunately does happen on the THP engine).
lancia58
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Re: THP Engine fault P2177 - Mixture regulation fault : Mixture too lean.

Post by lancia58 »

All the timing gear was replaced 2 years ago. So I guess the timing is not correct or maybe the inlet camshaft is worn ? Using a Lexia is there a way to validate if the timing is correct ? But the P2177 fault the car drives OK and it looks that there is no loss in engine power

Thanks