[Solved] Citroen C4 GP 1.6 HDI 109KM - Errors: P0401, P0490 and P1459

Hello

Has anyone on the forum solved the problem: air flow greater than set in 1.6 HDI / PSA?

For several months I have been struggling with EGR errors:



The problem manifests itself in choking / jerking of the car during acceleration (dynamic). The car stops when moving fast and around 2,000 rpm when it throws errors. The symptom of throttling is explained by the reaction of the EGR system to too much air flow - the controller receives information that there is too much air in the system and tries to reduce its volume by adding exhaust gases through the EGR valve. After jerking, the car does not enter emergency mode and accelerates smoothly to a speed of 170-180 km / h (tested on selected sections of the German highway).

I did the following to fix the problem:
1. EGR replacement - the original was blocking and Check Engine / Depolution crashed, so it was replaced with a used Valeo. The problem of EGR blockage kept coming back so I bought a new Valego. Unfortunately, it didn't help, so I replaced it with another one - this time an NTY replacement. There was hope and Check engine did not come back but the errors were still there. So I changed to another NTY as well and it's still the same as before. In total, I reworked the topic with four EGRs and there are still problems.
2. MAF replacement - the original had a short circuit and showed extremely high air temperature, so it was replaced with a used original, the short to ground and temperature error was resolved. After replacing the Check Engine stopped lighting up.
3. Intercooler cleaning - I rinsed the original one, checked for leaks and installed it. Unfortunately, no changes.
4. Cleaning the air mixer (I have a single one) and the intake with Liqui Molly - procedure with the engine running. Unfortunately, no changes.
5. Vacuum transducer - I replaced it preventively to ensure proper control of the turbo blades. By the way, I checked that the blades and the barbell work smoothly without jamming and the wires are tight. Unfortunately, no changes.

I am asking for help and tips because I am slowly running out of patience.

Is it possible to take logs while driving? How does the vacuum, turbo boost (set and actual), throttle position, fuel rail pressure and EGR opening (set and actual) behave around these 2,000 rpm?

This engine already has a variable geometry turbo, no? In my opinion, it is worth checking if it is not jammed and therefore does not work badly.

I understand that at the moment there is only P0401? Here is a good description of the algorithm, how the coefficient is calculated and why there is an error:
https://www.elektroda.pl/rtvforum/topic3448511.html#17141290

Check carefully the pins in the egr and ECU bones. They liked to bend and lay eggs

What EGR valve do you have there - vacuum, electric? Rather electric because that would be a mistake.
Too much flow is a permanently closed EGR.
The controller checks the flow with a flowmeter - if the EGR is closed, more air is drawn through the flowmeter. If the EGR is open, the flow of air through the flowmeter is reduced, because exhaust gas enters the engine instead of air. This can be seen in the description of the error P0490.
Can you see the opening of the valve at idle and the reduction of its opening when the load is increased, i.e. when starting?
After starting the engine, when it is warmed up and left at idle, the EGR should be open, it should start to close when moving off.

The engine sucks in 682mg/stroke and the recommended dose is 416mg/stroke, which shows that 266mg should come from the exhaust gas and it does not, i.e. the EGR is closed or not open enough in this situation.
Check if there are any plugs there or, for example, the EGR wires have become dirty and there is no proper flow through them.
I would also recommend, for example, to connect a potentiometer instead of the EGR valve and see if you can see the reaction to turning the potentiometer in the measurements.

@smykm
The guy above writes well.
If the egr is closed, the air dose will be higher.
Clearly the fault is in the valve or its connection.
Do a short test with a connected computer - it's best to download some desktop recording software, turn on lexie and take a ride.
Or look at the stop.
When adding gas, the egr should close and immediately after releasing it should open - at a standstill at idle it is open for about a minute (for me) and then closes.
Do you see that the egr opens when gassing? Well, unless it was a stabilized ride.

Thanks everyone for joining the discussion. I'll try to add more measurements tomorrow.

For now, I attach the error logs that are saved in the vehicle log.


PS EGR is electric. Turbine with variable geometry regulated by vacuum bar - checked does not jam. The sidewalk was mechanically cleaned about 2 years ago and was in good condition. The DPF burns out every 250-300 km. From the time when the jerk burns an average of 6.2 l / 100 km, previously I had within 5.8. I'm changing the fuel filter today.

@smykm
Combustion mixed mode or city?
Anyway, 6.2l is a good result.

@quiet coke

I gave the combustion in mixed mode from the computer. Resets every time you fill up (fills always full).

Added after 20 [minutes]:

Added screenshots from yesterday's rehearsal. The car has a new fuel filter.
Information about the intake air circuit at idle after starting the car.



Information about the intake air circuit after adding gas



In addition, I recorded the parameters while driving and noticed a certain relationship: when the car jerks, the "measured air flow" parameter increases in a second, for example, from 300mg to 400mg or even to 600mg, and then changes to the set value within 2-3 seconds.

Are such rapid changes in air flow not the result of a faulty flow?

@smykm
Does the egr close when gassing?
Does it shut down at idle?

These dumps do not say anything because it is not known whether they are made at the beginning of gassing or when you have stabilized the gas pedal.
At a standstill right after starting or shortly after, etc.

As a matter of fact, unfastening the ankle from the flow should clarify the topic. Egr with the ankle disconnected from what I remember does not work at all and the dose of air is constant.

@quiet coke

I posted a video of the test at a standstill on a hot engine after driving, engine temperature 85C.



1. EGR closes during gassing.
Then for a moment the copying is 0% but the RCO of the valve then displays "invalid value" - is this normal?
In addition, the 0% value is displayed with a delay - is this normal?

2. EGR does not close at idle even after a minute.
The valve opening is within 24% and is identical to the set point.

After disconnecting the flow, the engine does not stop and the car is more dynamic.

@smykm
1. There is actually a delay, but I don't know if it's normal - there is no delay in my car.
Your valve is open during gassing, it closes only at the end of the gas supply. For me, it closes almost immediately, so that I have a preview through the elm327.
In my free time, I'll hook up lexia and show you how it looks with me.

2. The valve should close at idle and I am sure of it because it is so in most cars, if not in all cars.

Is the egr valve closed all the time after disconnecting the mafa?

cichy koksik wrote:

Is the egr valve closed all the time after disconnecting the mafa?

I'll check and let you know tonight.

@cichy koksik, please confirm how the "RCO of the exhaust gas recirculation solenoid valve" parameter behaves with you - when the EGR closes after a minute at idle.

@smykm
I do not have this parameter (maybe it is named differently), but it is as I wrote - the egr valve closes and the set value / valve position jumps to 0% and the egr valve itself to -5
You have to click on these values and the tooltips should say what the values for the closed and open valve should be.
Here is a screenshot of my winter parameters.

@quiet coke

On the screenshot you have EGR Copy = EGR Setpoint = 13%, i.e. EGR is open at 13% - i.e. it is not closed.
On the other hand, the feeder/air damper is closed, i.e. the supply of fresh air is limited and the car draws it partly from the exhaust gases. I'm right?

@smykm
No. The dispenser in this case applies to the dosing of warm air (omission of the egr cooler), i.e. from the egr and in this case it is closed, but you are a bit right because the air is taken to the max fresh plus exhaust gases (cooled).

In my opinion, the warm air dispenser is a solenoid valve that controls the bypass vacuum, but you do not have this element, so do not pay attention to this parameter.

Cold air is supplied to the max-throttle position 0%, i.e. open to the max.


Added after 1 [hours] 52 [minutes]:

So on quickly.
The above screenshot is idle speed right after gassing - egr valve open, throttle position open to the max.
This dump is idle after this minute - egr valve closed, cold air throttle almost closed, but it was done in winter, so now I think it would be open to the max.
I made a bit of a fuss with the above entry, but I'm writing this quickly.

@quiet coke
Ok, I get it, there is some logic to it
My C4 GP I behaves a bit differently but it may also be due to a different intake design.

I understand that in mine I have to check if the EGR closes after unchecking the flow and I will test it today.

How can I check if the fish pass is not cheating?
You replaced it yourself, so how did you come to the fact that it is damaged?

@smykm
Rather, the intake does not matter in our cars because the difference is only the baypass, which is extra for me.
The principle of operation is the same because now in the summer this bypass is not used (only to burn fap maybe).

What about the flow?
I don't know if she was to blame
I exchanged it, so to speak, in the dark and also had the opportunity to buy it for little money, so I took advantage.
In addition, the holiday coincided and then there were plus temperatures and the baypass didn't have to bother anymore and it was him who caused the problems (I hope) :)

The fact is that the air flow was greater, as it is with you, so that the differences were not huge and disconnecting the cube from the maf solved the problem of turbo pressure - hence this replacement.
After the replacement, everything was ok, but as I wrote above, the bypass did not open anymore.
After all, the egr (baypass) was to blame because there are no such circuses now.

You do not like this set value of the turbo position yet - why is it still at 100%?

@ silent coke

After disconnecting the ankle from the MAF, the car got power and does not jerk. The EGR is in the closed position and the setpoint is permanently set to "invalid value". I'm still wondering why after adding gas on the connected MAF, when the EGR showed 0%, the set value also showed the "incorrect value" parameter for a while.

Regarding the turbo position set value parameter, I also wonder why it is still set at 100%. It looks like the ECU is constantly giving the wrong value... or there is a connection problem.

@kortileski
friend, you wrote about connection problems. I checked the EGR and the cube sits very much on the pins. Now the question is where is the ECU cube?

@smykm
Question.
1. You checked the parameters under load and that's when the air flow is greater?

Remember that the flow rate may be higher at idle and this is correct.

2.With the turbo, nothing changes under load while driving and under load at a standstill?
I checked the parameters myself yesterday and the set turbo is often 100%, but it is not rigid.

3. Egr in this weather does not open even after the throttle on idle after a long drive.

Have you done an EGR adaptation? Because you have "unknown value" like an adaptive error. Hint #4 check the harness, power supply to the computer and EGR and, by the way, charging the alternator.

@quiet coke

ad1. At a standstill it is OK, i.e. the actual value follows the set value. The system is regulated without any complaints. The problem is when driving when adding gas, as jade eats at a constant speed, it's also OK.

It seems to me as if the turbo was blowing too much, but not so much as to reload and throw an error. Note that in the video the turbo pressure is always higher than the set pressure.
I replaced the vacuum transducer but it's still the same.
Now he wants to measure the vacuum - because if it is too weak, the turbine blades are set to blow strongly and there will be too much air.
Alternatively, I'm thinking of adjusting the barbell....
Below is a diagram of the operation of the blades in my turbine:



and here is a nice video:
https://www.youtube.com/watch?v=KgVrpiFfp8U

ad2. It doesn't change at all

ad3. For me, the EGR opens quite often, In the morning "on the cold" I have peace for about 2-3 minutes and then I feel its interference by adding exhaust gases and jerking. I think this is a erroneous operation that results from too much turbo pressure. Then the EGR intervenes and tries to reduce the amount of air in the intake.

@hektar Zahler
What patent do you have for beam checking?

ad4. I have done EGR adaptations several times, but by "replacing parts". I can't find the EGR adaptation option in the diagbox, there is only its replacement.
I did not check the bundle, I disconnected the cubes at the ECU and treated with WD40.

@smykm
Re 1
From the video, the turbo works ok - such delays are normal, if you enter the charts, I suspect that the turbo set and actual values will be equal.
I wouldn't move the barbell.
Re 2
Doesn't the turbo set point change as well?
Re 3
In the morning on a cold one it should open right away and then you should be fine
Pay attention to the map sensor yet because it also affects the egr.
You also need to pay attention to why the computer keeps asking for 100 turbo items all the time.

I looked at old videos so quickly and my computer demands 100% turbo position when the egr valve is open.

cichy koksik wrote:

Re 2
Doesn't the turbo set point change as well?

The setpoint is always 100%...
The mapping changes. 15% at idle and 75-95% at idle.

I haven't found a similar case yet. On the English forum, the opposite situation was discussed, i.e. the set value was changing and the mapping was still at 100%.
https://frenchcarforum.co.uk/forum/viewtopic.php?t=60480

Added after 2 [minutes]:

PS Today I'm going to tap MAP and test the car on the road.

smykm wrote:

15% at idle and 75-95% at idle.

Okay, and under load?
It's best to make logs/graphs and it will be clear.
Throw in a few parameters and then compare, for example, to driving with the maf unplugged.

@quiet coke
What company did you buy the flow from?

The jumping of the measured air flow parameter under load (peaks to 600 and then drops to 300 in 2 seconds) does not give me peace.
I want to order a new one and I'm thinking about PIERBURG for PLN 370 vs OE SENSATA for PLN 360 vs SKV for PLN 222.

SKV will probably let go because the price itself suggests that the product is on the 2nd .

@smykm
I bought the original stimulant, but as I wrote, it was not really needed.
If I were you, I wouldn't buy a new flow.
As I wrote above, make logs / graph and it will turn out how it works.
And even better, buy an elm 327 and read the parameters - the app is very nice and extensive and most importantly, you can see all the parameters on a regular basis without jumping around the tabs in lexi.

There is fap in your car?

Added after 19 [minutes]:

I searched the net and found a similar problem to yours, i.e. a jerk and a jump in the dose of air.
The flowmeter (new) was to blame, but only partially-partially because it worked perfectly until the egr opened.
At that moment there was a momentary jump in the dose of air and a jerk.
Take a log and everything should be clear.
I do not know if there is no option to check the efficiency of the flow / test in lexia.

Added after 8 [minutes]:

I will poison again
I read that in the diagbox after replacing the flow, it needs to be "learned / loaded".
did you do it?
I mentioned it too, so I'm interested in the topic.

cichy koksik wrote:

There is fap in your car?

In the diagbox you can choose the parameters for the charts, I'll try to play with it.

Regarding training, I do not have such an option, there is probably only a replacement of parts.

After disconnecting the pass, the car works as it should - so the conclusion should be clear - a problem with the pass or EGR. I replaced both elements ... either I'm unlucky or something else is going on.

@smykm
So you've already regenerated fap.
As for learning, I actually did not see such an option, but I wrote about what I found on the web and there, as if on the website, someone performed such a procedure due to the undulating turnover - it helped.

As I replaced the mafa myself and had a moment of free time today, I became interested in it and it is as you wrote - replacement of parts. Maybe it's an apprenticeship, I don't know.
However, there is an option to check the correct operation of egr or mafa.

Play with these graphs and, preferably, turn on the desktop recording while driving so that you can see what was happening in the given conditions. Unfortunately, there are only 3 windows when recording, but it should be enough.

From today's driving, I can write to you that the maf basically constantly strives for the set value, but sometimes there are discrepancies.

Update :)

I replaced the MAF with a new original. The car stopped jerking. I haven't had a chance to test it on a longer route yet. For short distances, the problem no longer occurs.

Interestingly, I didn't even have to replace parts in the diagbox.