Rough idle 2012 1.2TSI 105BHP Manual

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Ash6R
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Rough idle 2012 1.2TSI 105BHP Manual

Post by Ash6R » Wed Sep 11, 2019 3:03 pm

So for the last two weeks I've noticed I've had a rough idle. The car has small shakes jumping between 630-650rpm, on small occasions it will jump to 700rpm and drop back down, kinda feels like its about to stall.

Around September of last year i had a similar problem but there will be small dips in power as well back then when under acceleration and i changed the spark plugs, ignition leads and the coil pack with NGK ones and it fixed that problem.

I must have have done around 10,000 miles since then, right now the engine is at 67,800 miles.

Does anyone else have similar problems or any idea what this could be?

I was thinking it might be the timing chain since i can hear a bit of a ticking sound on idle but im not sure since it doesn't seem to get louder when i rev the engine.

Could the spark plugs or leads have gone bad again in the 10,000 miles I've driven since changing it?

Any help appreciated!

exantas
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Re: Rough idle 2012 1.2TSI 105BHP Manual

Post by exantas » Wed Sep 11, 2019 10:28 pm

I have a car with the same engine and the issue you described but I don't know a solution yet. I have changed new sparkplugs and leads and didn't fix the issue for me.

Also recently I changed the timing chain cause it was rattling even when the car was in operation temps, but it didn't change the issue.


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Ash6R
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Re: Rough idle 2012 1.2TSI 105BHP Manual

Post by Ash6R » Thu Sep 12, 2019 12:32 pm

exantas wrote:
Wed Sep 11, 2019 10:28 pm
I have a car with the same engine and the issue you described but I don't know a solution yet. I have changed new sparkplugs and leads and didn't fix the issue for me.

Also recently I changed the timing chain cause it was rattling even when the car was in operation temps, but it didn't change the issue.


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I'm going to take it to my mechanic today and see what he says. Have you done any recent modifications that could cause it? I just remembered I installed a performance air filter and maybe that's the cause.

exantas
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Re: Rough idle 2012 1.2TSI 105BHP Manual

Post by exantas » Thu Sep 12, 2019 1:39 pm

No my car doesn't have any mods. It's all stock

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wolfie
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Re: Rough idle 2012 1.2TSI 105BHP Manual

Post by wolfie » Thu Sep 12, 2019 1:46 pm

Is the rough idle there all the time? I find with mine that when the engine is cold, immediately after starting the idle "hick-ups" give or take every 30 seconds or so, like the car has had a slight misfire. For me it's done it almost from day one. As part of a service I have recently replaced the spark plugs for some NGK IZFR6P7. If anything it's now slightly worse. It's not terrible, but it is noticeable.

Now when the car is warmed up it disappears completely.

I don't have time to search for the thread at the moment but you are not the first to have posted about uneven idle.

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Jay-Jay
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Re: Rough idle 2012 1.2TSI 105BHP Manual

Post by Jay-Jay » Fri Sep 13, 2019 9:15 am

Check again on the spark wires if there is oxydation on the contacts with the sparks and with the ignition coil.
The rough idle could be caused also by low quality fuel or some dirty injectors.
Eventually replace the fuel filter (placed under the car, close to the rear right wheel).

Ash6R
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Re: Rough idle 2012 1.2TSI 105BHP Manual

Post by Ash6R » Fri Sep 13, 2019 9:23 am

Well just got my car back and the mechanic said he couldn't find the problem :/ Not sure what else can cause this.
wolfie wrote:
Thu Sep 12, 2019 1:46 pm
Is the rough idle there all the time? I find with mine that when the engine is cold, immediately after starting the idle "hick-ups" give or take every 30 seconds or so, like the car has had a slight misfire. For me it's done it almost from day one. As part of a service I have recently replaced the spark plugs for some NGK IZFR6P7. If anything it's now slightly worse. It's not terrible, but it is noticeable.

Now when the car is warmed up it disappears completely.

I don't have time to search for the thread at the moment but you are not the first to have posted about uneven idle.
That's the same spark plugs i use and it helped my engine misfires last year. the rough idle seems to occur pretty much anytime its in idle. Can't tell if performance is affected, need to check my 0-60 time and compare it to what it was a few months earlier.

Ash6R
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Re: Rough idle 2012 1.2TSI 105BHP Manual

Post by Ash6R » Fri Sep 13, 2019 9:25 am

Jay-Jay wrote:
Fri Sep 13, 2019 9:15 am
Check again on the spark wires if there is oxydation on the contacts with the sparks and with the ignition coil.
The rough idle could be caused also by low quality fuel or some dirty injectors.
Eventually replace the fuel filter (placed under the car, close to the rear right wheel).
How does the oxidation look like? I was thinking it could be the fuel filter, is it a hard job to do?

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Jay-Jay
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Re: Rough idle 2012 1.2TSI 105BHP Manual

Post by Jay-Jay » Fri Sep 13, 2019 10:11 am

The oxydation looks like white (and sometimes green) dirt on the electrical contacts.
A friend of mine with the same engine had a rough idle problem similar to yours. He fixed it by replacing the high fuel pump, which was leaking a small amount of fuel inside the engine (contaminating the oil and loosing a bit of fuel pressure).
Have all these things checked out as soon as possible.

Replacing the fuel filter is an easy job.
When installing the new one, put a little bit of grease inside the fuel pipes, before reconnecting them to the fuel filter, otherwise it will be really hard to put them back in place.


wolfie
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Re: Rough idle 2012 1.2TSI 105BHP Manual

Post by wolfie » Fri Sep 13, 2019 1:41 pm

I don't have access to VCDS, but is it clever enough to count and log misfires?

It would be useful to know whether the misfire was isolated to specific cylinder, that could possibly point towards a problem with an injector, plug/coil. If the misfire was more random in nature might make you suspect a fueling related problem. Also if the cam chain is starting to stretch could it be enough to throw off the timing? (I'm pretty sure that can be measured. If not the absolute angles, the change over time)

I read somewhere that poor idle can be a sign of air leaks on the inlet side which cause issues with the car running too lean/rich. More noticeable at slow engine speed, not so much an normal speeds.

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