Fuel Consumption Spike? Peugeot HDI Troubleshooting

Hi,

I think I've found the reason why some PSA HDIs, especially the 1.4-liter engines, but also some of the 2.0-liter models, consume significantly more fuel.

Specifically with the 1.4 engine, there are vehicles that can achieve fuel consumption of 3-4 liters per 100 kilometers, while others consume up to 6 liters per 100 kilometers under similar driving conditions.
I recently disassembled one of these engines, and I noticed that in 3 out of the 4 cylinders, the piston ring grooves for the two compression rings were directly aligned with each other, meaning there was no angular offset. In the fourth cylinder, I observed an approximate 20-degree offset.

These engines can also be identified by the fact that they release over 40 liters of blow-by gas per minute at idle, while more efficient ones typically have a rate of 18-24 liters per minute.

Anyone experiencing similar fuel consumption issues with the same or a similar engine is welcome to investigate.

By the way, this thing is quite interestingly designed: it features a detachable aluminum block with a cylinder liner unit in an open-deck design .

Best regards, Johannes.

Luckily, I have one of those savings books! Do you have any pictures of the 1.4 HDI?

No, but I can make some if you want.
What exactly are you interested in?

Interesting approach – but then the compression would also have to be measurably lower. Do you have any values?

Everything you can photograph meaningfully! Since you apparently have/had the engine completely exposed, my interest lies in the cylinder head (valves and valve train, on both sides), the fuel injectors, the cylinder liners, the pistons (shape), the crankshaft, and - if the engine was removed - the location of the sensors. But please don't do any extra work!

Quote:

Interesting approach - but then the compression would also have to be measurably lower. Do you have any values?

I didn't measure the compression itself, but I did measure the analogous amount of airflow (see my first post in the thread).

Quote:

if the engine had been removed - the location of the sensors.

The block stays inside.

Sensors: there aren't that many of them on the engine...

- Crankshaft position sensor at the timing belt pulley.
Crankshaft speed sensor at the pulley.
- Rail pressure sensor (located in a very awkward position, directly below the fuel injector, making it almost impossible to remove the connector without causing damage).
Fuel temperature sensor located on the return line control valve, just above the high-pressure pump.
- Engine oil sensor (oil level), installed from the top rear into the oil pan.
- Oil pressure switch: located at the front of the engine block near the main oil channel.

The charge air temperature sensor seems to be available only from Euro4 onwards for the eight-valve engines; older models only have an airflow meter. It is usually located in the short section of charge air hose.

Another crucial detail: the housing of the original water pump is made of plastic, and the pump is driven by a timing belt .

Here -> https://community.dieselschrauber.org/en/viewtopic.php?p=155511#155511 are the desired images.

Thank you for your description and the pictures! My engine is an 8HZ, which appears to be the Euro 4 modification of the older 1.4 HDI with Euro 3. However, I don't know exactly what changes were made.

Regarding my questions: Does the oil level sensor only trigger an alarm when a minimum level is reached, or does the oil level indicator (ignition on, graphical bar display in the instrument cluster) function correctly? I have never seen anything other than "full" displayed, even though I measured approximately 2/3 of the fill level with the dipstick.

If I'm correct, the boost pressure sensor and intake air temperature sensor are combined into one unit on Euro 4 models. Accessing the fuel rail pressure sensor might require removing the lower engine compartment cover and possibly disassembling part of the wheel arch liner. It might be easier to access it from underneath with the vehicle raised.

The plastic water pump is indeed a ticking time bomb. It often only takes minutes between a slight leak and the complete failure of the housing. In this case, every (!) replacement part available on the open market is better and more durable than the original part. This also applies to other original spare parts, where a friend who works as a mechanic at Peugeot already buys replacement parts from the aftermarket trade.

Quote:

Thank you for your description and the pictures! My engine is an 8HZ, and it appears to be the Euro 4 modification of the older 1.4 HDI with Euro 3. However, I don't know exactly what changes were made.

You're right. At the very least, the software of the engine control unit is very different.

Quote:

Regarding my questions: Does the oil level sensor only trigger an alarm when a minimum level is reached, or does the oil level display (ignition on, graphical bar display in the km-display on the instrument cluster) function correctly? I have never seen anything other than "full" displayed, even though I measured approximately 2/3 of the fill level with the dipstick.

So, with the one I have at the workshop, the display of an intermediate value also works. Although, it probably deserves to be called a "guess-o-meter" rather than an oil level gauge.

Quote:

With the rail pressure sensor, it might be possible to damage something by removing the lower engine compartment cover and disassembling the corresponding wheel arch liner.

Negative. The clutch bell is located underneath it. It's generally more centered than on the left edge. It will probably be easier to remove the rail rather than trying to work on it there with little chance of success.

Quote:

The plastic water pump is indeed a ticking time bomb. The time between slight leakage and the complete bursting of the housing is often only minutes. In this case, every (!) replacement part from the open market is better and more durable than the original part. However, this also applies to other original spare parts, where a friendly mechanic at Peugeot already buys aftermarket parts on his own initiative.

At PSA, I'm now glad that at least the crankshaft, connecting rods, and pistons are still made of metal .

Quote:

At PSA, I'm now glad that at least the crankshaft, connecting rods, and pistons are still made of metal icon_lol.gif

.

That makes me jump off the sofa! I should also replace the water pump sometime. I need to check when the timing belt needs to be replaced. It's best to do those things together! I really don't like this "plastic pump" ticking time bomb.

Quote:

I need to check when the timing belt needs to be replaced. It's best to get it done together!

As long as the vehicle is not subjected to excessive stress, it should last for approximately 240,000 kilometers.
Unfortunately, the one I have in my workshop currently only has about half of its lifespan left, and the belt is already becoming brittle, and the water pump has noticeable play. It's a strategy by PSA to prevent the cars from becoming "too old" .

According to the maintenance manual for my 206: "240,000 km or 10 years". In both cases, the water pump will fail before that! This means many customers will probably never need to replace the timing belt on their 1.4 HDI engines...

While it's important not to overlook the positive aspects of the engine/car:

- Radiator removal: Requires 2 screws and 3 hose clamps, after which the radiator can be pulled upwards with one hand.
- Add 3 more screws and 1 connector, then the electric fan can be removed.

- There is plenty of space to work between the timing belt and the side wall.

- After 130,000 km, the engine shows very little signs of wear on the connecting rod bearings, piston rings, connecting rod bearing housings/piston pins, despite the fact that there is no intercooler when running at a boost pressure of 1 bar (relative), and that under low load conditions, the EGR system heats up the intake air (up to approximately 120 km/h -> NEDC).

What's still worrying me a bit is that there's a section of hose directly next to the loader/oxidizer on the pressure side of the oil supply line. If this hose were to burst or deteriorate, it would almost certainly cause a fire. Whether this concern is justified will become clear as more 1.4HDis engines age over time...

The hose can probably be replaced preventatively with a stainless steel braided hose. Even though it's supposedly easy to work on the engine, Peugeot calculates around 1000 EUR just for replacing the timing belt and water pump, although the water pump likely needs to be done first.

Replacing the radiator becomes more complicated when an air conditioning unit obstructs access to it.

Do you know if it's possible to disable the EGR system or at least reduce its flow rate?


The 1.4 HDI engine _suffers quite a bit from the extremely high intake air temperatures, which actually makes faster highway driving with this knowledge almost impossible. The temperatures, starting at 140 degrees or higher even with light acceleration, begin around 120 km/h, and consequently, the efficiency drops rapidly. To somewhat compensate for the noticeable loss of power, one tends to press the accelerator more, which results in further increases in boost pressure and a significant increase in fuel injection volume. Even at 130 km/h, the performance drop is very noticeable, and my Scangauge already shows a load demand close to the 100% :wink:mark:roll:. The exhaust temperature is also displayed near its maximum value. Anyone who believes they need to keep up with speeds of 160 km/h or more with the 1.4 HDI is already driving at full throttle in its standard configuration and can consume up to 10 liters per 100 kilometers on Euro 4 models. The majority of this fuel is converted into heat.

My upgraded intercooler, while providing more volume, has caused a noticeable turbo lag when starting, but hasn't really solved the problem. I can now reach about 125 km/h before feeling a significant drop in power. The intake air temperatures have only decreased slightly. There's a noticeable improvement at country road speeds, but hardly any difference on the highway. Overall, the car feels subjectively more responsive on country roads, although I can't say exactly how much of that is just my imagination. The fact is, I don't want to make any further performance modifications because I believe the thermal load on the entire system is already at its limit. How much additional efficiency can be extracted from the engine, which is being forced with hot air, is likely very small.

It was also worthwhile to extend the air intake duct downwards, where it can draw in air more protectedly, but gets significantly cooler air. Where it normally draws in air, it's exposed to all the heat buildup from the engine and the adjacent turbocharger. The engine bay of my 206 is very well sealed by a three-sided hood gasket, so the heat can only escape downwards. However, the lower engine compartment cover prevents airflow through the engine bay for aerodynamic reasons. I replaced the surrounding rubber seal with a continuous roll that is interrupted every 5-6 cm along its length. This material is used around the side and rear doors of various touring buses. It prevents the hood from rattling but allows heat to dissipate. A beneficial side effect on the 206: A fogged or frosted windshield clears up quickly, even after just a few meters of driving, without using the heater, due to the dissipating heat.


While these changes can be dismissed as minor tweaks, } every little bit helps! I have tested all the modifications individually and in combination, using OBD feedback, and I got the impression that the overall concept has been somewhat improved with these measures.

The 1.4 HDI will never be fast or sporty. It excels more with its incredibly low fuel consumption, provided you accept the limitations of the 1.4 HDI and use it in situations where it performs well. In terms of torque, it offers almost as much as current 1.8-liter or 2.0-liter gasoline engines, but at half the cost. If you adopt a relaxed, stress-free "French driving style" and only need French speeds (90 km/h outside urban areas, 110 to 130 km/h on highways), then you have a full-fledged small car with 5 seats, some trunk space, and fuel consumption figures that even a Smart driver can only achieve with a very light touch on the accelerator.

And: Unlike the Smart aggregates that were dying en masse, this French masterpiece seems to be quite durable. The engine construction in your pictures shows me a modern and well-thought-out powertrain that was only ruined by a cost-cutting measure in the periphery! All of this just to avoid internal competition with the then-not-yet-mature 2.0 HDI!! } In fact, the proven pre-production models of the 1.4 HDI had 90 horsepower and (!) a turbocharger.

Quote:

The hose can certainly be replaced preventatively with a stainless steel braided hose.

I'm more concerned about the hose slipping than it bursting. Oil hoses coming loose aren't exactly a new phenomenon, especially not in French cars...

Quote:

The radiator replacement is no longer quite as straightforward when an air conditioning unit obstructs access.

Ist bei dir der Klimakühler extra montiert, oder am WaKü. angeschraubt? Foto?

Quote:

Do you know if and how it is possible to disable the EGR valve or at least reduce its flow rate?

You can either disconnect the vacuum hose or the metal tube. This will create an error code, but it won't trigger the check engine light.

Quote:

The 1.4 HDI engine, incidentally, suffers quite a bit from extremely high intake air temperatures, which actually makes faster highway driving almost impossible with this knowledge. Temperatures already reach above 140 degrees Celsius even with just light acceleration and start at around 120 km/h, and consequently, the efficiency drops rapidly.

Yes, unfortunately. We once measured 170°C in the summer. That's because the relevant conversion curve (voltage to temperature) ends at that value.

Quote:

To compensate, one gives more gas, which results in the boost pressure being further increased, and the injection amount also increases significantly.

First, the fuel injection amount, then the boost pressure based on the exhaust volume flow.
As a result, the intake air temperature increases, and the reduced cylinder filling causes the mass airflow sensor (MAF) to reduce the fuel injection amount. This is particularly noticeable when overtaking on a hill (if you dare to do so ).

Quote:

The intake air temperatures have decreased only slightly. There's a noticeable difference at country road speeds, but hardly any change during highway driving. Overall, the car feels subjectively more responsive on country roads.

Okay, which engine do you have installed? Is it the one from the 1.4 HDi 90, the 16-valve version, or the 1.6 HDi?

Quote:

The fact is that I don't want to make any performance improvements.

You don't do that with the LLK either.
In the torque range, the engine operates at its maximum power output, while in the power range, it operates at its torque limit. This applies at moderate altitudes. At high altitudes with low air pressure, the torque limit is likely to be reached sooner.

Quote:

The proven pre-production models of the 1.4 HDI engine actually had 90 horsepower and (!) a low-pressure turbocharger (LPT).

There are also production models of the 1.4-liter engine with 66 kW/90 PS. As mentioned above, this is a 16-valve engine. It's more commonly found in Ford vehicles, where it typically uses a Siemens ECU.

Quote:

I'm more worried about the hose slipping than it bursting. Oil hoses coming loose aren't exactly new, especially not in French cars.

That explains the hose clamp that was replaced during the last maintenance (which, in my opinion, was unnecessary) at exactly this location.

Quote:

Is the climate cooler installed separately at your place, or is it attached to the water cooling system?

I think it was a sandwich construction method, but I need to double-check.

Quote:

Pull the tax hose or sheet metal.

There will be an error entry, but no message via the warning light.

Disconnecting and sealing the breather hose will definitely trigger the check engine light (MIL).

Quote:

This is probably one of the differences between Euro 3 and 4 standards.

First the injection amount, then the boost pressure via the exhaust volume flow.
As a result, the intake air temperature increases, and the reduced cylinder filling causes the mass airflow sensor (MAF) to reduce the fuel injection amount. This is particularly noticeable when overtaking on a hill (if you dare).

You wouldn't do that!

Quote:

While it's possible to overtake in flat areas if you can build up some speed beforehand, otherwise, it's best to avoid it. This also applies to other cars, because even if the driver presses the gas pedal slightly, I might have to abort my overtaking maneuver. It's not uncommon for someone who was previously driving 70-80 km/h to absolutely refuse to let anyone overtake them.

Ah - which engine do you have installed? Is it the one from the 1.4 HDi 90, the sixteen-valve version, or the 1.6 HDi?

I think it's from an Opel Agila or Corsa-C 1.3 CDTI.

Quote:

A friend said it might be a 1.7 CDTI from an Astra-G. I'm not entirely sure (anymore). It came into my possession and, after some adjustments and the creation of custom brackets, was installed. Unfortunately, it wasn't necessarily optimal; to achieve that, I would have had to remove the front skirts. For aerodynamic reasons, the front is quite closed off. This negatively affects the airflow. However, this did somewhat alleviate the heat problem.

There are also production models of the 1.4-liter engine with 66 kW/90 PS. As mentioned above, this is a sixteen-valve engine. It is more commonly found in Ford vehicles, where it features a Siemens ECU.}

I'm not talking about those! The test vehicles had eight-valve engines that were supposed to be mechanically similar to my 1.4 HDI. However, they were direct competitors to the 2.0 HDI and, for business reasons, were therefore discontinued and disappeared from view.