1.2tsi shudder/cough/stumble under acceleration, help :)

[pontiff]

hi all,

First off. Hi... I'm new here, but have had polos for many years (I ended up fixing and giving away over 10 6N polos over the years) but now I have a lovely 6r 1.2tsi which i love having done 192,000 kms (120,000 miles)

Problem though.... under acceleration say < 3k in gears 2-6 (its a manual) I get this shunting / driveline knocking.

I have replaced the spark plugs and HT leads (many times) to no avail.

If I clear the adaptions from the ECU via my vagcom the problem momentarily goes away until it creeps back again which leads me to believe its a sensor. So far I have also checked

- No faults logged in DME
- O2 Sensor A/F ratio as looked at via OBD appear to be okay, in so much as what the engine requests the AF ratio to be, is what it is close enough as measured by the O2 sensor.
- Knock sensor is not triggering\
- No misfire codes detected.

Has anyone seen anything like this before? It feels like its 'coughing' like its either getting too much or not enough fuel and stumbling.

Cheers,
Aaron from Australia

[blackertracker]

Could be a camchain or tensioner problem. I think 2010 1.2 TSI had camchains and at 120k miles I’d have it checked. VW had quality issues with a batch of chains that were wearing prematurely. I think they also had design issues with the tensioner.

[benzinkopf]

have a look at your ignition transformer/coil that serve the power to your ignition cable


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[pontiff]

Could be a camchain or tensioner problem. I think 2010 1.2 TSI had camchains and at 120k miles I’d have it checked. VW had quality issues with a batch of chains that were wearing prematurely. I think they also had design issues with the tensioner.

Correct... I have had mine changed (twice actually)

[blackertracker]

Could be a camchain or tensioner problem. I think 2010 1.2 TSI had camchains and at 120k miles I’d have it checked. VW had quality issues with a batch of chains that were wearing prematurely. I think they also had design issues with the tensioner.

Correct... I have had mine changed (twice actually)

Good man! I really liked that engine when I test drove one years back. I always try and get a camchain engine if possible, just a shame VW skimped on parts quality for a while. I currently have a camchain 6C Polo GTI with no issues.

[blackertracker]

In that case have you checked the coil pack? Does it have 4 x coil over plug or 1 coil pack?

I had a similar issue on our Golf 2.0 Mk4. I checked the engine at night, spraying some water on the coil pack and saw sparking as it was cracked. Changed it and fixed the problem.

[blackertracker]

Check your engine mounts too maybe if it’s a shunting/knocking noise under acceleration/gear changes.
I fixed a Hyundai i10 recently which had this and it was just the lower engine/gearbox mount loose.

[pontiff]

In that case have you checked the coil pack? Does it have 4 x coil over plug or 1 coil pack?

I had a similar issue on our Golf 2.0 Mk4. I checked the engine at night, spraying some water on the coil pack and saw sparking as it was cracked. Changed it and fixed the problem.

Im not sure what the cbzb 1.2tsi has, i want to say a single one (I think)... ill check tonight

[RUM4MO]

If I was a guessing man, I'd think that that car has a single coil unit with 4 O/Ps which is why you have reported replacing the HT leads already, the belt driven engines were the ones that got COP - ie Coil On Plug, ie individual coils.

[pontiff]

Yeah, they are a single coil, i checked. I Reset the adaptions and it still does it, so that was not it. Its pretty bad now, anything more than say 30% throttle under 3k and it throw a fit. Checked vagcom again today, no misfires being reported, nothing. Very annoying.

Is there a way to check the coil when its an intermittent fault like this one? I.E I cannot make it fault while sitting idle?

[RUM4MO]

The trouble might be that if it is the coil pack, then it might not be failing frequently enough to log a misfire fault code. At idle the cylinder pressures are lower so that could be, if it is the coil pack, why it is stable/steady at idle - ie if the coil pack output is low or the coil is otherwise potentially faulty, then it is under less stress at idle revs.

[blackertracker]

Yeah, they are a single coil, i checked. I Reset the adaptions and it still does it, so that was not it. Its pretty bad now, anything more than say 30% throttle under 3k and it throw a fit. Checked vagcom again today, no misfires being reported, nothing. Very annoying.

Is there a way to check the coil when its an intermittent fault like this one? I.E I cannot make it fault while sitting idle?

Like I suggested, at night spray some water on the coil pack then start the engine. You’ll see sparks if it’s leaking current. It’s a really easy check to do.

[pontiff]

Cool, I will do that, thanks

[jonessa]

Hi - i'm suffering from the same issue. Was it definitely the coils?

Thanks

[SamEvans]

I had a polo 6R 1.2 TSI. Felt almost like a misfire or clutch slipping. Changed the spark plugs and leads....it was a new car again.
Not sure if you’ve tried this.


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