Noise on cold start

[olaf]

Hi. This is my second post since I bought a 118TSI last July. It's generally very quiet except on cold starts when it's significantly louder, making some sort of a rattle (I wish I could describe this better). The noise disappears soon after I start driving but it doesn't sound right. I think it appeared after about 3 months.

I took it to Barloworld in Botany (Sydney) and they updated the software said it was fine. It's obviously still there. So what do I do now? I could take it to another dealer, but where? Or should I take it to a reputable independent VW repairer (suggestions please) for an early first service. The car has just done 10,000ks.

Thanks a lot for your suggestions

[noone]

I don't know about your specific car, but my VW has a feature where air is pumped into the exhaust system to help warm the CAT.

It is very noticable in the RPM, holds about 1k rpm for 20-40 sec, then settles at around 800rpm.

Does this sound similar?

[olaf]

Thanks for the prompt reply. It could be something like that. I'll have to check in the morning when the car is cold.

[cme2c]

Hi. This is my second post since I bought a 118TSI last July. It's generally very quiet except on cold starts when it's significantly louder, making some sort of a rattle (I wish I could describe this better). The noise disappears soon after I start driving but it doesn't sound right. I think it appeared after about 3 months.

Sorta sounds like a diesel, if it's like my 118TSI. IIRC it's mentioned in the manual as the hydraulic tappets pumping up.

[Greg Roles]

direct injection is a bit noisy too...

[cwcarruthers]

Mine does this too. I think, as suggested, it is normal and designed to warm up the engine as quickly as possible.

Cold engine = bad fuel consumption.

I'm not sure of the technical details - is this "exhaust gas recirculation"?

[Coaster]

My 118TSI is quite rough on cold start, the idle is a little inconsistent and a bit noisier than usual. I just put this down to the fact these engines are finely tuned compared with your average 'Genfordyota' engine. Once warm it runs sweet and is extremely quiet on idle, even quieter than a small VTEC.

[logger]

Mine does this too. I think, as suggested, it is normal and designed to warm up the engine as quickly as possible.

Cold engine = bad fuel consumption.

I'm not sure of the technical details - is this "exhaust gas recirculation"?

I think you are probably correct, internal exhaust gas recirculation. Because it is "internal" EGR by way of valve overlap, you get the rough running, as compared to the older system that used a dedicated valve between exhaust and intake manifolds.
Although my understanding it is an emission control strategy. Perhaps to get the CAT up to operating temp asap. I have noticed that exhaust gas temp (VCDS) skyrockets rapidly during this brief period of rough running to something like 650 degrees then drops significantly again, coincident with the return smooth running.
My car has always done it and I have just considered it perfectly normal.

[Corey_R]

Yeah - I think too many people are just a bit anxious about their new babies and strange sounds.

It doesn't help that they're not really comparable to older cars due to new technologies and new regulations.

Even 5Litre V10 BMW M5's sound rough on start - almost diesel like, until they're warmed up. VERY different from the sound of most typical Australia 5L cars

[pologti18t]

Yeah - I think too many people are just a bit anxious about their new babies and strange sounds.

I also find it interesting that people take it to a dealer and then don't believe the answer and are willing to take it to another dealer.

Is it about worrying about the noise or not liking the noise (ie I want the dealer to get rid of it)

[265coupe]

Entirely normal behaviour to shop around a fault. Been happening for years with illness and doctors, called a second opinion.

[cwcarruthers]

I also find it interesting that people take it to a dealer and then don't believe the answer and are willing to take it to another dealer.

Is it about worrying about the noise or not liking the noise (ie I want the dealer to get rid of it)

Answers are more believable when they are explained clearly and not given with a "shutup, get lost" attitude. I can understand that when the answer is a dismissive "there is no problem", and that is all, that it is hard to accept.

[pologti18t]

Answers are more believable when they are explained clearly and not given with a "shutup, get lost" attitude. I can understand that when the answer is a dismissive "there is no problem", and that is all, that it is hard to accept.

Except that none of that was mentioned in the original post....

What is exactly wrong with the response "there is no problem"? Should it be supplemented with "they all do that" to make you feel good?

[seangti]

it's a fine line for mechanics and the amount of detail people want to hear about the car. Does the average joe want to know how and why the recirculation works??? Probably not. Are they talking jargon to confuse me and not fix the problem???

Though as many of us on here have some level of mechanical knowledge, or at least appreciation, an explanation is quite reasonable to expect.

[logger]

Here is a VCDS log to show what goes on. TSI118 cold start.xls Pretty much confirms that rough idle ceases once EGT and CAT temps peak at 665c. Start plus 40 seconds. At this point IEGR ceases and lambda emission control activates.