[Azariel]

First of all - welcome,

I have 2009 i30 with 1.6 CRDi engine, 90hp, no dpf on board.

It has 75kkm now and I've experienced some rattling when accelerating & had oil level rising slightly. It also happens sometime when warming up(around 70 celsius degrees) that around 1700rpm when accelerating engine drops power. however when ~80 is reached it does not happen any more.

I decided to go to authorized hyundai dealer to ask what's wrong but they told me that everything is fine and I should not worry about excessive oil level because turbo will "suck it" (LOL).

Then I drove to proper diesel service - the problem was that 2 out of 4 injectors needed to be regenerated. Reason for that was faulty fuel pressure sensor that was replaced, however.... fuel pressure is more stable but still not acceptable! It is 5 weeks now when service is checking every other sensor, EGR, ECU maps, high pressure fuel pump was tested... and still nothing!

Do you have any idea what may be a reason for fuel pressure to drop? Mechanic refused to give me car back since driving in this condition will only make injectors to suffer once more (well, it makes sense).

Any piece of advice will be much appreciated...

Regards,
Leszek

[Dazzler]

  Leszek

I'm not able to suggest any other possible fixes but hopefully Phil or Tim (Our resident Hyundai Technician) will see this and be able to help in some way.

[Azariel]

Currently service will take a look of fuel pipes, fuel tank and a pump near the tank - we will see if it helps. Next step would be to visit another authorized HY service for expertise.

I'm particularly curious about the only symptom so far except rattling - why the heck is power loss experienced only within the range of 70-80 Celsius degrees of cooling fluid? And it happens only when accelerating delicately - when given more than 1/3 throttle or when idle it works fine!

 

[Phil №❶]

Are we talking low pressure from the tank, or low pressure from the high pressure fuel pump 

[Azariel]

Phil,

thanks a lot for picking it up!

Mechanic says that despite having high pressure pump checked in specialized workshop and sensor changed (BOSCH 0 281 002 863 I believe) there are still significant pressure drops on the rail (i.e. high pressure as I conclude).
He also told me that with the new sensor pressure is much more stable but still not within acceptable range and thus he says it may still be a thread for the injectors.

May it be the case that because of blocked fuel pipes, fuel tank, faulty pump by the tank fuel pressure on the input of CR pump is to low and it translates into too low output pressure?

[Phil №❶]

Low fuel pressure from the tank could be caused by the following,

- Diesel fuel poor quality or waxy, due to cold conditions.
- Tank fuel pump faulty.
- Diesel bug or water contamination in tank.
- Blocked fuel lines.
- Blocked or dirty fuel filter. If filter shows black tarry substance, that is Diesel bug.

[Azariel]

That's what is being checked right now - I hope if any of the above is the case they will find and fight it, but...

Any other ideas what may be the cause? I try to anticipate next phone from mechanic saying "well, we've cleaned it, it should be fine but still pressure is not stable"

Any why I can feel it only within 10 Celsius degree range? 

[Phil №❶]

The 10 degree range sounds like a sensor problem affecting the injectors. The amount of fuel sent to the injectors is a result of sensor information and ecu programming.

[Azariel]

All right, so maybe it's gone with the new sensor on board.

I hope cleaning the fuel lines, fuel tank and checking pump by the tank will help. If not I will just go and lose my mind 

[sundiz]

I had fuel pressure problems. I changed the whole fuel filter assembly (and a new filter). In my case the filter assembly was the cause.  It seems that the filter assembly broke down and sucked air to the fuel system which caused drop of the fuel pressure.... After that fix my car has worked as it should. You can find more info in the "Limp mode home" topic...

[Azariel]

Sundiz - thanks for information, I know they did change the fuel filter however I doubt they checked assembly. Are you aware of any method how to check if that's the problem without replacing assembly for a new one? Any experience?

[sundiz]

Sundiz - thanks for information, I know they did change the fuel filter however I doubt they checked assembly. Are you aware of any method how to check if that's the problem without replacing assembly for a new one? Any experience?

I don't know if there is any "right way" to check the filter assemblys condition. Only way I can think of checking the filter assembly system is to add some extra transparent fuel filter to the line which goes from the filter to high pressure pump. They cost probably couple of euros... If the filter assembly is faulty, you should see some air bubbles in the transparent filter.

When I had limp mode problems, I asked from the dealerships mechanics about the filter assembly and if I should change it. They said that they have had couple of cases where the filter assembly let air in to the system which caused problems. They also said that that is "cheap" to fix. (I paid 270€ for the part. Changed it myself). They said if the problem were in the injectors it would cost +1000€ to fix...

I remember reading couple of cases here on the forum, where the filter assembly was the cause for the limp modes.

I'm just guessing, but the filter assembly could be the problem. If you end up buying a new filter assembly and you are not in a hurry, I suggest KORAPS or EBAY... I paid 270€ for local dealer (quite a rip off). I could have bought same part with 100€+ shipping from KORAPS.

I've read that during warranty time these filter assemblies have been replaced in some cars. I guess it is a known problem in these diesels. But in these modern cars there are a lot of other stuff too which could be the cause for limp modes... Hard to tell what is the real cause, especially over internet 

[Azariel]

Well, they checked filter assembly and it seems ok - in fact I was not experiencing limb mode.

Update - fuel lines from the tank to the engine checked and cleaned - still nothing. I am waiting till friday to visit authorised hyundai service (another one). I will wait and see...

[cruiserfied]

Sorry to come in late on this one.
So far they seem to have done ok with their testing but you havent mentioned if they have tested the suction side of the high pressure pump. There is no pump in the fuel tank, fuel is drawn up the lines via a suction pump which is integrated in the high pressure pump.
I cant think of any reason to feel the lag only between 70-80*c other than temp sensor malfunction.

[Azariel]

cruiserfied - thanks for advice, I wil ask if they also checked suction pump however it was tested by company that specializes in CR pumps regeneration so I assume they did.

I happend to drive around ~500km with liquy moly diesel spulung added to fuel and I experienced no lag when accelerating (if it brings anything to the topic).

Regarding temp sensor malfunction - they told me that pressure regulation sensor was broken and replaced. May it be the sensor responsible for the lag? Or should I also ask them to check temp sensor?

[cruiserfied]

Id probably give it a while and see how it goes. You dont want to go doing unnessacary work if you dont have to.

[Azariel]

Hi, bit of update : it was diagnosed with short circuit that's causing fuel pump to malfunction. Will be repaired on Monday and if that helps on Tuesday I'll get it back. Fingers crossed!

[Dazzler]

Hi, bit of update : it was diagnosed with short circuit that's causing fuel pump to malfunction. Will be repaired on Monday and if that helps on Tuesday I'll get it back. Fingers crossed!

Sounds promising! 

[cruiserfied]

Hi, bit of update : it was diagnosed with short circuit that's causing fuel pump to malfunction. Will be repaired on Monday and if that helps on Tuesday I'll get it back. Fingers crossed!

But the fuel pump is entirely mechanical. Unless it's the inlet metering valve or pressure relief solenoid. Hope they know what they're doing.

[Azariel]

Hi again,

I received my car today - working silent as never and consuming even less fuel than before!
To conclude:

Problem: rattling injectors and fuel leaking into engine oil, lack of power between 70 and 80 Celsius degrees of coolant.
Solution: Two injector tips replaced, all injectors regulated and adapted(225E) + malfunctioning pressure sensor/regulator replaced(125E) + wire with short circuit replaced (60E) + engine oil replaced (50E)

Looking for solution workshop did also: replacing fuel filter, checking high pressure pump, checking and cleaning of fuel lines and tank, checking if ECU map is original

It took 6 weeks and costed 1/10 of car value but I can enjoy my i30 again and I hope that with 74k km and other parts working perfectly I will not need to visit any service soon.

Thank you all for your help - it is very appreciated. Cheers!

[Phil №❶]

So glad you're in love with your car again. 

[Azariel]

Nothing lasts forever. 2000 km driven and engine rattles again when cold + power drops when accelerating.

With the same angle of acceleration pedal from 1,8 krpm to 2,3 krpm it accelerates smoothly, then from 2,3 krpm to 2,4 power drops to ~50% of what it was and from 2,4 krpm on it accelerates again as it used to!

Car's back at workshop. Let's see what they figure out...

[Dazzler]

Impressed with your patience. Some of us would be ranting by now!

[Azariel]

Some news:
It was diagnosed with faulty computer/driver. Service told me that it is rejecting correct application and thus engine is working with inappropriate fuel dosage.

Now I handed it to electronic who is supposed to find second hahnd, working computer, reprogram it to my keys etc. and bring it back to life.

Could it get any worse?

[Dazzler]

 

[diesel1984]

Some news:
It was diagnosed with faulty computer/driver. Service told me that it is rejecting correct application and thus engine is working with inappropriate fuel dosage.

Now I handed it to electronic who is supposed to find second hahnd, working computer, reprogram it to my keys etc. and bring it back to life.

Could it get any worse?

I think that changing the ecu(and buying one) isn't right way to solve engine rattling problem.
You can try to swap it with used ECU from scrapyard just for test.

Did they checked wiring, ground, cables for stripped isolation, fuses, timing, faulty sensors, DMF rattle(if installed).
Diagnostic live data, scope reading...

First thing that i will check on that list with rattling is oil pressure on cold.

can you put a video of rattling sound, maybe someone can help you before you throw any more $$$$$

[Azariel]

diesel1984 - all you've mentioned was already done - few cables replaced and after few thousands km's ECU rejected new application - then rattling and all problems came back.

I have it stated on paper by hyundai dealer that this is the problem. If changing ECU won't help I'm definitively not going to pay for that.

[Azariel]

Hi folks,

update for future generations: in fact it turned out to be faulty ECU + driver of whirl flaps (not sure how to name it properly, it is responsible for opening and closing flaps in air intake to swirl it).

After reprog ECU worked fine but with each and every km program in memory was chaning byte by byte... I bought used ECU, cloned EPROM from old one and put brand-new ECU map. Now it's perfect!

Also problem with gap/loss of power around 2000 rpm was caused by flaps driver mentioned above. TBH I didn't even know that such part exists in diesels... :o

I hope this time that would be it.