Citroen C4 2.0 HDI - uneven engine operation. Injections out of calibration P026

mkaminski100 wrote:

Errors that occur constantly are:
P0266 - Cylinder 2 - contribution/balance error
P0269 - Cylinder 3 - contribution/balance error
P0272 - Cylinder 4 - contribution/balance error
P0098 - Temperature signal on the collector
(-) And of course I will check the EGR, although its damage here would be detected and ... possible damage to the beam.

Does the engine start without problems? Does it only run bad at idle? Does it lose power while driving, smoke and work unevenly? If this is the case, the injectors cannot be operational during start-up and fail immediately after firing. If they are out of calibration, as you called, then there are total problems with starting and non-stop while driving.

From what you can see in the tables, everything with the injectors is OK, the correction is normal, but it is only idling (800 rpm). You don't have key parameters fuel pressure in the tray, injector overflow test and power supply to the injectors . There is simply not enough data to make any accurate diagnosis. You should collect a few tables at different speeds on the street, carrying a laptop on your lap. Then memorize everything on the computer, print it out and analyze it calmly.

Insufficient use is made of the injection computer, which controls the engine in 100% from the moment the key is inserted into the ignition. And too much hammer, screwdriver, blind replacement, without sense and without thinking. Since the computer controls, it also diagnoses, and thus detects faults on an ongoing basis using the sensors surrounding it. Why don't you drive around with a laptop on your lap and read what the computer has to say? Below, I am pasting an exemplary table consisting of nearly 40 parameters, which contains information generated by the computer when controlling injection, air charging, exhaust gas recirculation, etc.

I suggest, first of all, to exclude the most important injectors in the engine. You just have to answer the question whether they are working or not working. If there are faults in the controller memory, such as in the pictures, i.e. P0266 , P0272 and P0269 , saying unanimously that injection time is too long or too short (eng. Injection time too long or too short ) - means probably very strong transfers to the tank . As a result, the high pressure pump (pwc) cannot keep up with the compression of the fuel in the amount needed for injection. The injectors are leaking at the control valves and fuel is escaping into the tank instead of into the cylinders. Hence, the injection is too weak or disturbed, because the pressure in the accumulator constantly drops.

I direct you to a thread that talks about the first generation HDI engine, but the symptoms and diagnostic procedure are the same for each generation of this system here . This is my last titled post Is there an injector failure option? Also pay attention to the issue metal filings in the fuel.

When the injector tests fall out absolutely perfect and there are no metal shavings in the fuel circuit, the next issue to consider would be exhaust gas recirculation (EGR) and / or mass air flow meter (mpp) . These are the next two elements most often failing in the HDI unit, responsible for jerking, uneven rotation, black smoke and power loss.

Kiss KotBury2

mkaminski100 wrote:

I noticed a slightly rubbed wire of the harness (it was wiped by the engine cover) and I wonder if sometimes a puncture on the injection cable will not cause such revelations. I do not remember the injection voltage exactly, but it is probably around 100V, so there is a chance of jumping a spark.

That's right, the abrasion of the cables (twisted pairs) can be the cause of total interference in the operation of the injectors. What type are they electro-hydraulic , Whether piezoelectric ? Be very careful when measuring during start-up and idling with these first injections: the current and voltage are respectively 20A and 80V in the phase of pulling the needle out of the nozzle socket.

However, in the case of piezoelectric injections, manufacturers forbid any measurements and even approaching the electrical installation due to the voltage reaching even 250V .

I have already stated in one thread that it is best to check the current with current clamps, an oscilloscope or special devices intended for this purpose, shown in the pictures here .

Kiss KotBury2

mkaminski100 wrote:

The injectors are definitely Siemens (Conti) and piezoelectric to my knowledge.

Well, you have a serious "sickness", because without an oscilloscope, current clamps or a special device you are not able to make electrical measurements on a running engine, and thus confirm full efficiency electricity injectors. Attention! The electrical plugs of the piezo injectors must not be disconnected while the engine is running as this may lead to continuous injection as the control valve may stick in the "open" position. There is a risk of destroying the engine by melting the bottom of the piston.

However, you can easily measure it capacity piezo injectors using a capacitance multimeter. The engine is of course turned off, the electrical plug is disconnected and the meter's terminals are connected to the injector pins. Unfortunately, I don't remember the nominal value that should be for this kind of measurement.

In turn, you can perform other checks on your own (apart from the obvious need to insulate possible abrasions of the injector strands), which will at least partially lead you to injector faults, namely:

1. Overflow test . It is always the first and basic check of the technical condition of both electrohydraulic and piezoelectric injectors. It answers the question whether the "top" of the injector is fully operational, i.e. control valve with a plunger or ball (7, 9, 10 - figure below).

If the elements of the control valve are damaged, worn or attacked with metal filings, it simply does not hold pressure, it just leaks. Fuel is therefore not injected into the cylinder at this point, but escapes in excessive amounts to the overflow. We then say that the overflow is too large and this usually forces the injectors to be regenerated by replacing the control valves.

Below are shown details of damage to the valves and other injector elements visible only under a microscope.

The overflow test can be carried out by yourself by installing several lengths of transparent PVC plastic tubing with an internal diameter of 4 mm and four vessels, preferably cylinders, with which you can measure how many ml have overflowed from the injectors. There are many videos on YT showing this. here . I note that the author of the video is surprised that fuel is pouring from the disconnected overflow pipe, even though the injectors have plastic pipes connected. This is obvious because the overflow pipes serve the entire fuel system, not just the injectors. The overflow is thus collected from the fuel filter, from the high pressure control valve (zrwc) and goes to a common pipe. Prevent the fuel outflow by plugging the side opening, or bend the fuel hose or connect other hoses with cylinders.

However, it is not advisable to constantly move injectors from cylinder to cylinder for experimental purposes, although it seems to be the simplest. And yet this is not the case, especially in relation to piezoelectric injections, which must be subjected to the so-called injector coding . This should be done using an external diagnoscope, and you don't seem to have one?

Another recommendation of the service manual says that the violation of threaded connections does not guarantee the tightness of the system with unimaginable pressure surges 2000 bar . It's better to use non-invasive techniques, which you prefer anyway...

2. Checking if the fuel circuit is free of air . To do this, you observe the transparent fuel line in the low pressure circuit while the engine is running at various RPMs. It was assumed that the diameter of air bubbles cannot be greater than 3mm and is then considered normal. However, much larger blisters testify to air fuel circuit. The cause of the aeration should be found and brought to full tightness and throughput fuel on the way from the tank to the entrance to the pwc. Therefore, not only tightness is important, but patency. Such a banal example of a decrease in patency is clogged fuel filter that must be replaced immediately.

3. Checking whether the flow regulator is electrically and/or hydraulically damaged (2 - diagram of pressure regulation in the SIEMENS system below).

Expenditure regulator (2), otherwise low pressure dispensing valve or suction throttle valve is the most important valve in the engine. It plays an absolutely key role in regulating the fuel pressure, as it determines the amount of fuel allowed into the pwc.

In short, the greater the current the computer supplies to the electromagnetic coil of the regulator, the more fuel will flow from the low pressure vane pump (1) to the pistons and cylinders (3) in the pwc. The more fuel pwc has at its disposal, the more pressure it will create in the injection circuit and the more fuel the injectors will get. Conversely, the less current the computer supplies, the less fuel will flow between the pumps and, as a result, less high pressure fuel will be delivered to the injectors.

Therefore, the regulator fulfills a very important task balancing fuel pressure produced by pwc, a used through the injectors. If there was no such regulation, the fuel pressure would "jump" dangerously from extremely low, threatening very uneven operation and stopping the drive unit, to extremely high, threatening to burst the system.

The simplest check of the regulator consists in its temporary replacement with an identical engine and testing while driving. If the problems disappear, we buy a new valve. If they do not disappear, we are very interested in the power supply, i.e. in what condition are the cables and valve plug. There were accidents, e.g. bending of pins, corrosion, other ailments that prevented normal driving, despite the full efficiency of injectors and pwc. The same applies to the pins on the side control computer .

4. Checking whether the transfer is fully unobstructed high pressure control valve (zrwc) on pwc
One of the purposes of the application zrwc (4) in layouts Common Rail is to support the flow regulator (low pressure dosing valve) described above (2). The support includes in the fact that at a critical moment, e.g. too large pressure jumps in the tank, the computer gives current pulses to return (4) to divert excess fuel to the tank overflow. The fuel pressure in the tank drops. The overflow pressure must not be greater than 1 bar .

However, if, for example, the overflow hose (11) becomes clogged with metal chips, the pressure rises above 1 bar and it becomes impossible fuel pressure adjustment , despite an efficient regulator (2). It's just that the fuel, instead of escaping from the open zrwc overflow into the tank, "goes back" and obviously effectively inhibits the internal flow of fuel from place to place. We then say that the overflow is disturbed, and thus the normal operation of pwc and injectors is also disturbed. The engine starts to work unevenly, smokes and loses power at full load, despite the impeccable condition of the injectors and the entire injection circuit. The clogged overflow from the pipe (11) to the tank is to blame.

Checking is simple, disconnect the flexible fuel hose from the connector (11) and start the engine. Not a drop of fuel must flow out of the tube (11) while cranking the starter motor. However, when the engine starts idling and we gas it by increasing the revolutions at a standstill - from the pipe (11) fuel should only drip, but never pour a copious stream . If the last symptom occurs, it means that it is damaged zrwc (4) electrically and / or hydraulically .

Another experiment after disconnecting the overflow pipe from the connector (11) will be the reaction of the engine. If the unit works very badly with the tube fastened on the stub (11), and immediately returns to normal after removing the flexible hose - this means overflow clogging at some point on the way to the reservoir, which is what we're talking about.

The same situation applies to injector overflows. If any flexible overflow pipe of the injector is clogged (no. 7 on the diagram of the SIEMENS injection circuit below), then there will be strong disturbances in fuel injection, including the cessation of injection, despite the impeccable condition of the injectors. It's possible that you may have the same transfer glitch.

Attention! It is probably the same type of 2.0 HDI DW10BTED 136 HP engine that is installed in Peugeots. Among other things, their characteristic feature is the location of the pwc (1-5) on the side of the gearbox with the drive from one of the camshafts. The toilet pump does not have a toothed wheel and timing belt, but is bolted to the body, and the drive is a wedge clutch embedded in the camshaft .

5. Check that no metal filings reside at the bottom of the fuel filter can . You will find the closest description and commentary on this matter, for example here and here .

Kiss KotBury2

mkaminski100 wrote:

there was an error P1195 (open injection) but it does not specify which one. (-) I would be very grateful for tips.

If you have an error

Quote:

P1195 - Injector control, injector blocked in open position,

means the situation described at the beginning of post #9, it is as if you unplugged the injector electrical plug while the engine was running. Then, continuous injection takes place, because you have non-stop injection channels to the cylinder. You are then at risk of burnout of the piston in the cylinder.

So, from now on, focus only on the injectors, do not distract yourself with EGRs and FAPs, because they do not contribute to the terrible work of the engine.

Your primary task is to be 100% sure, not 50 or 70%, of the condition of the injectors. I gave you directions for the overflow test and you should check what is going on that the injector is probably "pouring".

Don't give any other readings, because they are worthless anyway because you take them at idle (about 800 rpm) and not while driving with a laptop on your lap. It is only then that various shortcomings and deviations become apparent when the engine is under load. At idle, the computer perfectly picks up all the "play", so the readings are mostly impeccable.

First of all, be guided by a very disturbing error P1195 , without the solution of which there is no question of normal driving.

Kiss KotBury2

mkaminski100 wrote:

Do I remember correctly that French cylinders are counted from the chest?

Yes, it counts from the flywheel, not the timing. Do I remember correctly that you had trouble with the 4th cylinder all the time? So, despite the exchange of injectors 1 and 4, a very high correction of 140% was still maintained on cylinder 4. Yes, this means a decrease in compression in cylinder No. 4, but also problems with the power cables (twisted pairs) that you have supposedly frayed? So if the damaged cables touch the metal parts of the engine, the fault will still persist on cylinder 4, despite the injectors being swapped. Which can be completely operational, only cables for d...

In addition, by not coding injectors in the computer, you cause confusion in their control, because other cylinders have different conditions, e.g. there are constant differences in cylinder tightness, i.e. compression, which the computer has registered in memory and takes corrections for these differences during each injection.

In short, acting in the dark, at a glance, you create more and more mess, until in the end not only will you have to replace injectors, and who knows if burned pistons, but also the computer will have to end up in the trash...

In my opinion, you should focus on the injection system, because only it is able to "shake" the engine. He will never jerk FAP even if it's 100% clogged, and you seem to have a 50% fill rate. EGR can jerk, but only in a strictly limited range, i.e. rather at idle and does not stop after warming up. The EGR also smokes profusely black. A damaged flow meter can also contribute to the same symptoms. However, from the diagnoscope readings, there are no major deviations from any of the above-mentioned elements.

Therefore, leave the exhaust alone for now, otherwise you will not have 1 or 2 faults, but 22. I suggest you take it for checking five things:

1. Injector overflow test

2. Checking the power supply to the injectors

3. Cylinder compression test (without triggering injectors)

4. Reading current parameters while driving with a laptop on your lap

5. Are there metal shavings in the fuel?

You can see that you're trying to get along without anyone's help, you know, abroad, that's glorious. However, unfortunately, in this type of engine, you can't do everything with a hammer and screwdriver. Plus, you seem to be asking questions as if proforma and you do it your way anyway?

Kiss KotBury2

mkaminski100 wrote:

So it's not like I'm scheming without anyone's help, but having only a moment I try to do what I can finish in one day and at least exclude these elements. Advice is very helpful, but I am also asking for understanding and patience, because there is no time.
In addition, I do it myself, so I also have a limited workshop and not everything at hand.

Sorry, I've already corrected my "aggressive" tone, as you misunderstand. I just wanted to guide you on the right path, and what you do yourself is your absolutely independent brooch. So I only suggest, and I don't demand and I don't insist, that you focus on the injectors and the injection system for obvious reasons: even if the whole EGR, FAP, sensors and other side elements were released, none of them does not cause jerking or uneven rotation . Anyway, the computer does not detect anything disturbing on this side, so why waste time? For peace of mind, you can temporarily blind the EGR dosing valve so that it does not cause side disturbances in the combustion of the mixture in the cylinders.

Now a few corrections to your last statement. Unfortunately, this 3rd generation SIEMENS or CONTINENTAL engine and injection system requires injector coding. This is the list of European injection systems below. Yours is described in the last line.

ad. 2 and 3 . I strongly advise against a compression test with the method you are about to use. It was useful 30 years ago, but not in Common Rail where every unsealing of the injection system of very high pressure (above 1000 bar) threatens irreversible damage. In the same way, constantly removing the glow plugs to access the cylinder may cause the spark plugs to break, as they are ceramic. If the tip of the candle remains in the head, or do not give Providence, the tip of the injector, it is a complete intestine, threatening, at best, to ream the holes left by the remains of the above-mentioned elements. These are not fears of Lachy at all, but numerous cases known to me from autopsy.

So I propose a completely non-invasive compression test, namely the method starter current drop, battery current drop or on an existing one crankshaft rotation sensor . These are extremely simplified methods that do not require disassembly of injectors or glow plugs. All you need is an oscilloscope and a current clamp. You will, in a sense, come into possession of these instruments:

Quote:

Anyway, I may have an oscilloscope, but next week,

so I don't see a problem to use them for other measurements. On request, I can provide a detailed description of this method. I'm not doing that in this post because it would take up too much space. For example, I am pasting only two oscillograms from the compression test with the starter current drop method. The second one clearly shows damage to the 4th cylinder, as the mechanic said - caused by the burnout of the exhaust valve.

ad. 4 .

Quote:

That's why I wanted to check the timing.

If you had the timing shifted, you wouldn't be able to start the engine at all, and you apparently smoke without any problems. In addition, in the second line after the revolutions, in each data table you pasted - you have timing synchronization, YES . If there was something with the timing no teges , then this line would be NO.

ad. 5 .

Quote:

In my opinion, there was something, but after pouring it on paper, I don't see anything disturbing.

Do not pour anything on the paper, just check the bottom of the filter can for shavings or so-called "golden flour". I can't remember if the filter on your engine is replaceable or non-replaceable. If it is disposable, it can be disassembled either expenditure regulator , or pressure regulator (shown in my previous posts) and watch their sitkas as in the pictures below.



Kiss KotBury2

mkaminski100 wrote:

You can write more about the method of measuring compression that you gave because it is interesting.

You speak and you have (I reprint my own text from another forum). Despite the fact that the current drive units from the HDi stable and not only work on a different principle than "classic" diesel or VW/Audi unit injectors, a sufficiently good tightness of the combustion chambers is still needed. It is necessary to compress and heat up to 900 degrees C a dose of air enclosed in a cylinder. Only then a dose of fuel is injected using injectors Common Rail (i.e. under very high pressure of 1800 bar and more) can ignite successfully.

If the combustion chamber is leaky for some reason, then self-ignition is strongly defective, for example due to too low ignition temperature. The engine then starts with difficulty, after repeated ignition several times, emits a lot of smoke from unburnt fuel, and has uneven idle speed. While driving, it also shows bad symptoms of work through some noises, power loss, sometimes jerking and high fuel consumption. All this is happening despite the impeccable condition of the injectors and other starting elements, such as the starter motor and the battery.

Therefore, one of the first checks that is carried out on every diesel engine, when there is a suspicion of damage to the piston rings or any element of the "keyboard", is to perform a compression test. It is also needed due to similar symptoms occurring when injectors fail. It is therefore necessary to determine what is to blame - the cylinder or the injector.

It is wise to check both. However, it does not have to be done automatically when, for example, it is known that the user has just recently replaced a set of injectors. It is unlikely that all four pieces will work badly, unless metal filings have got into them. The latter should be taken care of by each driver himself, checking whether there are no golden metal shavings or so-called gold chips at the bottom of the fuel filter can. "golden flour".

So we naturally conclude that the cylinder compression test should come first. When the "classic" TDI and TD turbo diesels were in use, it was enough to unscrew the injectors or glow plugs from the head and insert the appropriate adapter with a measuring probe in its place, then turn the crankshaft to measure the compression pressure of each cylinder in turn.

For even more accurate measurements, the oil or compressed air method was used, observing the rate of pressure drop and, on this basis, assessing the tightness of the combustion chamber. However, these were "physical" methods, because they required laborious preparations related to the removal of injectors, spark plugs, etc.

Why traditional compression test methods should not be used on your system Common Rail ?
When the era of Common Rail turbodiesel came, which probably won't end for a long time, the situation changed dramatically. Injectors and other fuel injection components work under very high pressure, so their threaded connections are extremely sensitive. Violation of the thread and reassembly exposes the entire system to loss of tightness. A thin stream from a leaking high-pressure pipe can easily cut off every finger, including the most important...

In short, any disconnection or opening of the very high pressure injection system, including the injectors, must be avoided at all costs. The same applies to the glow plugs, which, as said, are ceramic and it would be better not to touch them than to touch them even for a compression test.

So there was a problem of "inviolability" of injectors during compression tests and not only, which can be easily solved by using the so-called. indirect, not direct methods of measuring compression pressure. There are basically three methods that are in use, or at least should be:

1. Starter current drop method.

2. Battery current drop method.

3. Measurement method on an existing rotary sensor (usually crankshaft).

For the purposes of this statement, I omit method 3, because you need a normal external diagnoscope with a built-in compression measurement function. Only a few, very expensive diagnostic kits, such as KTS BOSCH, VOLVO, etc., have them. It is rather doubtful that an ordinary workshop could afford such an investment of the price of C4, and maybe even more.

However, any self-respecting service should certainly obtain the necessary equipment to measure the indirect method no. 1 and 2, i.e. the current drop of the starter or battery. Well, two things are necessary for this: an oscilloscope, preferably a 2-channel one, and pliers, current clamps as in the picture below.

The purchase of an oscilloscope with a set of pliers, in my opinion, is profitable for every repair shop, because they can be used to "snap" the entire car electrics, including the signals of all sensors and adjusters. Whereas an ordinary voltmeter does not work because it is too slow.

Method #1 puts a current pliers on the starter cable and, when connected to an oscilloscope, runs the starter and registers a "miniaturized" milliamp current, which in reality draws up to 150 amps. Therefore, pliers are needed.

It should be remembered to prevent the engine from starting by the operation of the injectors, because as you know, it is about checking the cylinders, not the injectors. It is best to remove the plug from one or two injectors or the crankshaft sensor (depending on ease of access).

During a few seconds of turning the starter, current "peaks" should appear on the oscilloscope screen as in the picture below. The rest is in the picture description. These peaks indirectly symbolize the compression pressure on each cylinder, converted on the oscilloscope into current signals in the form of a sharp sine wave.

So the peak of each peak should reach as high as possible, which proves good compression, so in this case the sealed cylinder is the most resistant to the starter. Any "unevenness" indicates compression problems, as shown in the second figure.

With an efficient engine, we should read on the oscilloscope the current consumption of at least 35 A and the crankshaft speed of 200 to 300 rpm. A damaged cylinder can be easily recognized by the deviation of these two values. If the starter draws well below 35 amps and the crankshaft speed increases above 300 rpm, there is a loss of cylinder compression, etc.

As a reminder, why do you need a 2-channel oscilloscope. Well, one channel is not enough, as we cannot tell from the graph which cylinder is which. However, with 2-channel, we can connect to the camshaft sensor and thus locate the cylinder number.

Indirect measurement of the current drop of the starter (battery identically) is not as accurate as the oil or compressed air method. However, for our purpose of specifically detecting whether it's a cylinder or an injector, it's precise enough. However, it has a valuable advantage of extremely shortened preparation of the measuring station, without the need to remove anything from the head.

It is worth mentioning by the way that with the help of an oscilloscope, and only an oscilloscope, we can detect damage to itself pacemaker and battery . Which, unfortunately, is not possible with a multimeter that only measures a constant drop or rise in a signal, not so complicated and fast. As it is said, it is the strongest weapon against electricity and wherever even "branded" diagnoscopes cannot cope. In my opinion, every reliable diagnostician / mechanic should be armed with it, because cars packed with electronics will not end quickly, quite the opposite.

Can the compression drop fault be detected in other ways?
It should be noted that it is also possible to initially locate the compression drop fault using an external diagnoscope. Just download the relevant current engine parameters, print and analyze. The differences will be clearly visible in parameters such as injector correction (rows 7-10 in the table of parameters below).

Then, differences in real and theoretical fuel pressures, as well as differences in fuel injection dose, injection start, or injector power supply, will reveal cylinder leaks.

The best and most accurate compression test results are undoubtedly obtained using the sensor found in every engine TDC and crankshaft speed . In addition, it is an indirect method that does not require the use of current clamps, and therefore does not introduce the own error of the measuring instrument. However, it requires an oscilloscope or an additional oscilloscope function in available external diagnoscopes.

At the same time, the use of the oscilloscope itself requires tips that pierce the insulation of the sensor cables, which is not recommended due to possible signal interference later on.

As you can see, the choice of methodsThe number of non-invasive measurements, not only cylinder compression, is not small and it is worth investing in an oscilloscope, clamps, as well as an appropriate set of connection terminals between cable plugs and pins in the sensor or adjuster. This is to insert the so-called "adapters" that allow you to connect the oscilloscope using "nooks", not terminals that pierce the cable insulation.

Kiss KotBury2

mkaminski100 wrote:

However, I checked the fuel filter and there are no filings, but there is a slight rusty coating and the filter is slightly covered with it. I'm a bit surprised by this, because in the absence of filings, it turns out that the sediment comes from the gas station tank.

It doesn't necessarily have to come from a gas station. Fuel is not sucked directly from the bottom of the tank, but through a basket with a pre-filter. Thus, it is practically impossible to suck in any larger impurities such as rust, etc. Unless something happens on the way between the tank and the main filter. Such surprises can be caused by a low-pressure electric pump immersed in the tank. However, it is used only by BOSCH. SIEMENS does not put such a pump, but the suction basket with a pre-filter does.

In my opinion, whatever the deposits are, they are of primary origin in too "dry" fuel or causing strong, corrosive reactions of acid-like liquid on metal parts. If, for example, someone adds sulfuric acid to diesel fuel, the pwc will "strip off" not shiny, silver chips, but corroded, brown particles. All this goes to the injection circuit, and then returns to the tank through overflows. The particles are then sucked back directly from the basket and retained by the main filter. Hence their strange presence at the bottom of the filter can. If we find even a few crumbs in the filter, it means that they are everywhere, and therefore also in the hopper and injectors.

Generally, poor quality fuel is a silent engine killer. In your case, I am becoming more and more sure that these deposits are the main cause of problems with rotation, power and smoke. Well, but you do as you want, so you play with some EGR and other crap ... So I wish you good luck ...

As for the mention of compression measurement methods

Quote:

without knowledge of the exact parameter values, these graphs do not give anything

it's not about memorizing any values at all. After all, the point of a compression test is to find SIGNIFICANT DIFFERENCES between cylinders, not whether the compression pressure in the cylinders has any specific value. So let's not confuse our heads, excuse me, with d... and let's not fight with numbers, but with problems.

On the pasted oscillograms, you can clearly see which graph is correct and which is incorrect. Does it then matter that the compression pressure in a given cylinder is 15 or 20 bar, since they all have equally high current "peaks"?

How does cylinder compression relate to injector correction?
It is generally accepted in compression pressure measurements that a difference of up to 30% between cylinders is acceptable and considered normal. Because each CR engine (via computer) has the ability to compensate for differences, i.e. it can select "free play" up to 30%. A prime example of this ability is injector correction i.e. "idle leveling" Smooth Running Control - SRC ), shown in the figure below.

This is one way to automatically adjust fuel injection. It takes place without human intervention. Its purpose is to equalize the engine speed by adjusting the fuel dose to individual cylinders. The idea is to eliminate or minimize uneven revolutions caused by: differences in cylinder sealing, differences in friction, different hydraulic tolerances, different degrees of wear (play).

If one of the cylinders is "too fast", the other "too slow" (e.g. due to a decrease in compression), the following unfavorable phenomena arise: torque fluctuations on individual cylinders, uneven engine operation, increased exhaust emissions.

Injector correction is an element not only of improving the working culture of the engine, but above all of reducing exhaust emissions. It only works up to 1500 rpm, which is around idle, as this is the idea behind the correction. Hence, it should not be surprising that at idle (850 rpm) the correction "jumps" like crazy, and when we accelerate above 1500 rpm, the injectors inject 100%.

Injector correction is calculated by the computer based on the indications TDC sensor and crankshaft speed and fuel pressure sensor in the tray. If one of the cylinders is "too fast" in relation to the rated (set, standard, theoretical) rotational speed, the injection dose is reduced (minus correction).
In other words, the computer pulses the electromagnetic (piezo) valve of the injector accordingly less. Conversely, if "too slow" - injection dose is increased (plus correction). in a word, SRC corrects the fuel injection dose until the actual engine speed is equal to the required rated speed (here 900 rpm).

Pzdr KotBury2

mkaminski100 wrote:

there is very little of this sediment in the filter and it is a powder.

Well, nice, "very little", we can say the amount as in the photo below. Due to such a small amount of filings, the owner of this brushes he performed a general overhaul of the engine, because his pwc jammed and he had a piston-valve collision.

In my eyes, you usually have a bucket of so-called. golden flour, or powder, as you say, throughout the entire fuel circuit. You should actually be praying that some miracle happened and pwc didn't break the timing belt and the timing blew it...

In addition, I remind you of the fault code:

Quote:

P1195 - Injector control, injector stuck in open position. P0266, P0272 and P0269 - injection time too long or too short.

This means that the fault may be on the side of the electrical power cables (i.e. "injector control"), which have rubbed the insulation and there may have been a breakdown on the metal parts of the engine. So you can replace the injectors 20 more times, and the fault will not disappear, because you replaced probably fully operational injection apparatuses, but you did not replace the faulty cables.

The same applies to the replacement of the probably impeccably working old pwc, which only had to be cleaned of filings and then ensured its safe fuel lubricity by adding oil 2T . After all, you had fuel pressure readings and pwc always built these pressures correctly.

So I won't be surprised if the nightmare comes back again, since you're not 100% sure, just 50 or 90% sure that the injectors and not the cables are to blame. So I ask, where is the overflow test? Why do you act first and think later? No offense, but you're a bit like a novice who developed a strange condition not recorded in medicine, namely, the lack of connection between the brain and the wallet. A guy who's hit his wallet should start thinking... And you're not a novice. No offence.

What would I do if I were in the injured driver's seat?
I would try to make it as simple and cheap as possible. I would try to find out the reasons for the invasion of filings or other impurities in the fuel circuit. Since they got into the main filter and did not come from the distributor, they must have been produced by the engine itself. If they are metal filings, it "strips" them off with its very closely fitted pistons and cylinders ("precision pairs"). Also other moving parts in pwc participate in the "production" of chips, because they are loaded equally with cylinders and pistons, transferring mutual friction in the presence of "dry" fuel, as if sandpaper rubs against sandpaper.

Filings can be produced by injectors, but their participation has not been proven so far, because the "supply" of chips was provided by pwc. Assuming that the filings are produced only by pwc, they go directly to the hopper and all four injectors. So injectors, even being in impeccable condition, can be damaged by pwc, which "sows" filings in their direction. Therefore, it is a complete misunderstanding to try to heal the injectors with various miraculous liquids such as STP, SKYDD, XERAMIZER, DENATURATE, GASOLINE, ALCOHOL, which are supposed to clean them of carbon deposits, etc. Will these liquids be able to dissolve metal filings? In addition, will the injectors cause timing belt breakage and piston-valve collision even if all four become immobilized with chips or other debris? However, there will be a disaster if the chips are produced by pwc. And that is why, in the first place, we always save pwc from seizing, not injectors.

So the first thing I would try to do is stop the production of shavings in the fuel circuit. I would immediately apply as much of the blend oil as possible 2T to 2-strokes in a ratio of at least 1:100 . This is the dose of oil that I have practiced over 4 years on two CR engines, ensuring effective and safe lubrication of pwc and injectors. Safe, I mean no side effects of using the oil 2T . The drive units do not lose power, do not smoke and do not adversely affect the soot combustion process in FAP. After all, since the same oil is poured into gasoline, which is much more sensitive to ignition point deviations than diesel fuel, it will be even more beneficial for diesel engines.

The second thing I would do is flush out at least the fuel tank and other available elements of the fuel circuit, such as pressure control valves, fuel pipes, etc. For now, I would not disassemble the injectors and pwc, because, as you can clearly see, the system can eliminate the filings by itself by passing "in decline" to the reservoir through overflows. I would only carefully wipe the bottom and walls of the fuel filter can from filings and fuel residues with a paper towel, preferably for painting work (does not emit hairs). Of course, the paper filter element should be replaced with a new one, even if it was replaced yesterday.

I must add that I had similar problems with uneven revolutions in one engine (2.0 HDI DW10ATED 110 HP) and in the other engine the timing belt broke due to pwc jamming (2.9 CRDI 145 HP). Both cases were caused by too "dry" fuel. In the first unit with the BOSCH 1st generation injection system Common Rail I managed the same as above, i.e. wiping the filter can from the filings, then flooded 1 liter of 2T oil for approx. 50 liters of fuel . So I used a horse dose of 1:50. The engine has been working impeccably for well over 4 years, it starts "to the touch" in the greatest frost. As the saying goes, it works evenly, lightly and quietly ...

In the second case, it ended much worse, because the engine was overhauled due to a piston-valve collision as a result of breaking the timing belt. I've talked about it before and I won't dwell on it. Unfortunately, I also had to regenerate the injectors (DELPHI injection system), in which the mechanic found metal filings. After washing them and replacing the control valves, the injectors work flawlessly, and the engine returned to full life, of course, systematically supplied with oil 2T what we're talking about.

Kiss KotBury2