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Isuzu Forward (2004)

Isuzu Forward (2004) 1

Isuzu Forward (2004)

Without keyword

Diagnostics and repair of Japanese trucks

Received for repair car Isuzu Forward 2004, engine 6HL1, injection pump HP3 Denso.

The problems, according to the client, were as follows:
1. Engine power limitation (emergency mode)
2. Black smoke under load (more noticeable in the gearshift range 4-5-6 at the moment the limit switch is actuated on the accelerator pedal)
3. The particulate filter burn key did not respond to pressing.

Diagnostics revealed the following DTCs (error codes):
P1453 (too many delays in the diesel particulate diffuser).
P1454 (PM particulate matter diffuser too large).
P0044 (EGR, position sensor)

These errors are logically related. Therefore, we begin to carry out further inspection and repair from the source of errors – the regeneration system (EGR). During the repair, the book of the Legion-Avtodata company was used:

To understand the question:
· EGR & DPD is one piece, on a Euro 3 EGR car is less noticeable, but no less important.
· The difference is that on cars with Euro 3 there is no diesel particulate filter, but there is a catalyst. The catalyst clogs and fumes white smoke. The remaining symptoms are the same, only in emergency mode it does not become – that’s why the EGR value is less noticeable.
· On cars with Euro 2 there is no catalyst at all, but there is EGR – from all of the above, there is only soot in the intake manifold. With so much soot, the car suffocates, because “nostrils blocked”!
· On a car with Euro 4: soot, black smoke, DTC (no burning with DTC!), No increase in exhaust gas temperature in the particulate filter
· On all vehicles (without exception), with a large amount of soot, the following symptoms occur:
– unstable engine operation
– lack of power
– stalls on XX (if a lot of soot!)
– fuel system malfunctions

They are actually ordinary lack of air.

Now a little more detail: “EGR device and operation”

How the function of control of the recirculation valve is arranged and works:
· In accordance with the readings from the sensors, the engine control unit determines the opening of the exhaust gas recirculation valve, which during operation sends a control signal (displaying the opening of the exhaust gas recirculation valve) to the gas exhaust recirculation actuator.
· If it is necessary to prevent the emission of black smoke and unstable engine speed (during engine overload, when the emission brake is activated), the engine control unit stops monitoring the gas exhaust gas recirculation valve.
· The gas exhaust recirculation actuator activates the recirculation valve actuator and sends this information (display of the actual valve opening) to the engine control unit.
This operation allows the electrical control device to accurately perform the functions of controlling the opening of the exhaust gas recirculation valve.
From practice, I can say that with proper operation, the valve can work for 4-5 years.

When removing the EGR valve, it turned out that the valve itself was in the open position. The valve itself was covered with a thick layer of soot and stuck.

You can compare with the new EGR valve:

It makes no sense to repair in this situation: we change, check again and are satisfied with the first positive result: “the issue with black smoke and error P0044 is closed”.
After replacing the EGR valve, it is necessary to verify that there is no soot (soot) in the intake manifold and cylinder head formed during the operation of the engine with a faulty exhaust system. If there is one, then soot must be removed. Many ways.

The Legion-Avtodat company’s book says the same thing (you had to read it before!), Pay attention to the text in the frame:

Speaking of the DPD system. For beginners, an article on the Legion-Avtodata company portal will be useful: “DPD system. ISUZU vehicle exhaust emission analysis system (beginning of production of cars with DPD system – end of 2003) “, –

For understanding – another general scheme for the location of DPD:

But even now, judging by the cars that come to us for repair, we see that some owners of such trucks, without understanding the essence of the problem and also read the Internet, are trying to independently improve the engine, saying, “The Internet will not advise ” And then we see this:

The photo shows the result of the owner of the car, which does not lead to an improvement in the engine, but to the additional costs of acquiring a particulate filter. The photo clearly shows that they tried to “break through” it, believing that thereby “the engine will breathe and work better”.

To the question: “What leads to such a situation”, there is an answer:
“Lack of engine power, because the car is in emergency mode and there is no way to finish the regeneration of burning the particulate filter in manual mode by pressing the key (photo below):

Can a diesel particulate filter be scraped in a Japanese car? There are answers, different answers. The most common on the Internet: “It is possible. There will be nothing. But the engine power will increase and you will not have to spend about 100 thousand rubles”.
But let’s look towards Japan, the homeland of such cars. Japanese people are smart, right? And if this could be done, then the car would be equipped with “ordinary crowbar”. But there is no scrap in the kit. Means what?

Punching with a LOMOM particulate filter, the car owner deprives himself of the opportunity to restore the system, and also remains without a silencer, because the particulate filter replaces a conventional silencer with partitions on the car. If you just take and remove the particulate filter (assembled) from the car and put it to the side, then the same effect will be! Only an expensive element will remain intact and this is very important, because a new filter on Isuzu Forward costs 90,000 rubles (this is at the old prices, and God knows what will happen in our new next crisis). So look at the photo:

And remember: “You can’t do this.”.

Causes of malfunction (“clogging”) of the particulate filter

A variety of causes can cause this malfunction (clogging) of the particulate filter. Let’s consider some. First, general operating issues: “What you need to pay attention to the owners of the Isuzu Forward car with a 6HL1 engine”:
· More often look in the rear-view mirror when driving: puffs of black smoke appearing and almost immediately disappearing in the 4-5-6 gear shifting range at the moment when the accelerator pedal trailer has just worked. This is the first signal that there is a malfunction in the exhaust gas recirculation system (EGR valve). When connecting the scanner, you can see errors P0044 (EGR position sensor) or P0045 (EGR valve):

It is possible to check and verify the efficiency of the EGR valve using a scanner, using the function “test actuator”:

· If the EGR valve has already been replaced, it’s good to make sure that there is no excessive soot in the intake manifold generated during engine operation with a faulty exhaust system.

By the way, look how much soot is sometimes raked inside:

· You should also check the neutral sensor (DTC 6), since the exhaust system only idles when the engine speed rises:

If the scanner indicates a DTC P242F error (DPD obstacle) has been detected:

That means the following: the mountain brake damper actuator may be defective (in open or closed position).

· It is necessary to check the operability of the exhaust flap, as (rarely) it only works when the particulate filter is burned and is often faulty.

If all of the above is checked, working properly and there are no DTCs, then you can try forcibly (using a scanner) burn particulate filter.

How to do it:
· Connect the scanner
· Launch forced DPD regeneration
· Observe a rise in temperature
· If the exhaust gas temperature does not rise for a long time (DTC P2458), make sure that no one has plugged the exhaust manifold connecting the EGR valve and check if the exhaust radiator is clogged

· Repeat the burning procedure.

Next, we act according to this algorithm:
1. Connect the scanner, confirm in the scanner menu that we checked the engine oil level and delete the parameters of the old diesel particulate filter.
2. After performing the above procedures, DTC P1453 and P1454 do not temporarily bother us, and the particulate filter burn button will start to function – accordingly, it will be possible to check the DPD system.
3. After making sure that there is no DTC, warm the engine to operating temperature and press the particulate filter burn key.
4. On the scanner display, we observe an increase in the exhaust gas temperature.
5. If a temperature increase is not observed over a long period of time, then the operation of the rock brake flap and the exhaust flap should be checked. If the dampers are in good condition and there is no temperature increase, you will have to check the condition of the exhaust radiator and, if necessary, relieve it of soot and soot using a screwdriver and an electrode.

It is possible that during burning the engine temperature will increase to critical. In this case, the ECM (engine control unit) will stop the regeneration until the temperature drops to the operating temperature, and then the regeneration continues.

If during the operation of the vehicle and after successful regeneration the DPD lamp often starts to light up and the engine will require burning, then the fuel injectors should be checked. But this is a topic for another article..


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