[claude07]

Hi guys,
after chatting with other forum member, I finally found the time to ask you about your opinion/advice.

Few months ago I started having problems with my i30 GD 1.6 crdi, 81kw, 2015. When the outside temperature is above 15C, and the engine is cold (let's say the car has been left over night), and I start the car, for the first 3-5 seconds, revs start to go up and down (from 800 to 900), and the car shakes (same as the video below). After that initial happening everything is ok. It doesn't happen everytime, but more often when conditions for this issue are met (outside temperature, cold engine).

ilk çal??t?rma rölanti problemi 2 - YouTube

Since the car is under warranty, I took it to the dealers and the story begins... They took apart fuel system, changed fuel filter, O rings, but the problem remained. Then they took apart exhaust system, afterwards took out injectors for testing, everything cleared OK. I must point out that the car never showed any error.

Since the dealer had problems with forced regen for DPF (they'd start the regen, but could never finish it, GDS always said "regeneration failed"), they decided to change the DPF, so about a month ago I got a new DPF
The car has 104 000km, and is driven mostly with combined driving (city and highway). I had no problems finishing regens during normal driving...

Some say the problem could be faulty EGR valve, but the dealer said they checked it and for them it is ok - there are no errors on GDS. As one member suggested it, I tried turning on aircon during this occurrence, but it didn't make any difference, revs would still go up and down and the car would be shaking and creating some woosh-woosh sounds (sorry for the lack of better description, just trying to create o complete picture  )...

Some say it could be software issue... Dealer flashed latest software for whatever they could find, but no luck...

The problem is, since it is winter time here, the problem doesn't manifest itself. Dealer said the car is perfect, and they are saying that from the start, because whatever they tested or took apart for examination, is in perfect condition - the only issue they see, is this occurrence that sometimes happens - but doesn't affect driving or any other function of the car (as they say).
And yes, the problem happened when I took the car to them (I left it over night at the dealers, so they could see it first thing in the morning), they recorded data on GDS live record, but the problem went away when the temp outside went down. They've been at it for the last 5 months...

If anyone has any advice or had similar experience, please do share...

[Shambles]

I might be tempted to suspect the fuel itself, or contamination of it.

[claude07]

I tried various fuel stations, even different cities, no luck there...

[Dazzler]

Very frustrating.  Must say I'm pleased with how proactive your dealer has been trying to fix it. 

[nzenigma]

Hi @claude07 ,

The first clue is 15 deg C. 

Has your dealer looked at the MAF sensor or MAF signal?

The MAF waveform  to the ECU varies according to temperature and will activate the EGR valve.

[claude07]

@Dazzler, after the second month, my dealer didn't have any more ideas what to do, so they asked central dealer to step in, and have have done everything they asked them to (hence the new dpf)...

@nzenigma , yes, they claim that everything is ok with MAF sensor too (they did not try to replace it).

I'm not in a very good position at the moment, the problem is still here, dealer said for them everything is ok with the car, and my warranty is about to expire in 3 weeks 

[nzenigma]

Hmm... backed into a corner 

The motor sounds quite vintage, its the way old diesel tractors sounded as their mechanical governor moved to limit higher revs.

Can you get a cheap independent mechanic to give a second opinion?

Look at live data. Fuel pressure? Unlike us , you have a primary fuel pump in the tank. Is it efficient? 

Live data will display EGR open and shut. You can unplug the MAF (on outward side of air filter) when above and below 15C and see if it makes a difference.

[claude07]

@nzenigma , sorry for the late response...

fuel system has been checked and fuel pump was taken out, inspected, everything cleared OK.

As for EGR live data, I haven't tried that yet, I will soon...

Just to clarify, when it is colder, and I start the car, revs are higher (around 1000-1100 rpm). But when the temp rises, on the first start of the car, revs are around 800rpm (for that 5-6 seconds that revs go up and down, it seems like the car is trying to find somekind of balance - as if it doesn't know whether the revs sould be higher of lower)

[nzenigma]

@nzenigma , sorry for the late response...

fuel system has been checked and fuel pump was taken out, inspected, everything cleared OK.

As for EGR live data, I haven't tried that yet, I will soon...

Just to clarify, when it is colder, and I start the car, revs are higher (around 1000-1100 rpm). But when the temp rises, on the first start of the car, revs are around 800rpm (for that 5-6 seconds that revs go up and down, it seems like the car is trying to find somekind of balance - as if it doesn't know whether the revs should be higher of lower)

I will check my diesel when she arrives home.

From memory it is similar to the petrol motor. We are usually above  15 deg C . Cold start is 1100 rpm then drops to about 680 rpm over the next minute.