Golf MK6 77TSi - Misfire issue

[gonsped]

A couple of months back in late Feb 2020 - my 142,000km Golf MK6 77TSi was driving on the highway and I can feel some sort of surging or what at the time felt like transmission issue - the car felt like it was changing gears eventhough its not.

Engine warning light came on, turned the car off and restarted again and got the periodic surges until I brought it in to the local VW mechanic (not dealer) and they diagnosed it with misfiring and issues with a coil pack. So they replaced cylinder 1, a few weeks later, more misfire happening - especially in the 40-60km/hr range, this time they replaced cylinder no. 4.

Alas the next day from the mechanic its still there, now its even worse - it can happen at low range <40km/hr and even at higher speed - 7th gear @ 70km/hr. No engine warning light and never had a misfire ever before the highway incident.

What seriously odd is - there is NO misfire when the car is in manual mode or sport mode. What gives?!?

The timing chain was replaced by VW dealer on goodwill 18mths ago, clutch was replaced at around 80,000km. DSG mechatronics failed last year and was replaced on goodwill.

Engine runs real smooth and I use BP 98 RON always with Lucas oil Fuel treatment/injector cleaner.

I don't want to go back to the mechanic, spend $400+ and no result again. Any comments?

[cme2c]

A couple of months back in late Feb 2020 - my 142,000km Golf MK6 77TSi was driving on the highway and I can feel some sort of surging or what at the time felt like transmission issue - the car felt like it was changing gears eventhough its not.

Engine warning light came on, turned the car off and restarted again and got the periodic surges until I brought it in to the local VW mechanic (not dealer) and they diagnosed it with misfiring and issues with a coil pack. So they replaced cylinder 1, a few weeks later, more misfire happening - especially in the 40-60km/hr range, this time they replaced cylinder no. 4.

Alas the next day from the mechanic its still there, now its even worse - it can happen at low range <40km/hr and even at higher speed - 7th gear @ 70km/hr. No engine warning light and never had a misfire ever before the highway incident.

What seriously odd is - there is NO misfire when the car is in manual mode or sport mode. What gives?!?

The timing chain was replaced by VW dealer on goodwill 18mths ago, clutch was replaced at around 80,000km. DSG mechatronics failed last year and was replaced on goodwill.

Engine runs real smooth and I use BP 98 RON always with Lucas oil Fuel treatment/injector cleaner.

I don't want to go back to the mechanic, spend $400+ and no result again. Any comments?

First off, I would have replaced all coils and plugs. I did. In another thread, you can see that I have a similar weird problem with my 118TSI. I found a cheap Ebay OBD2 dongle and iPad software let me monitor what was going on. About $30 all up.

[gonsped]

I have another mechanic I'll get to take a second look. Do you guys have any idea roughly how much each coil cost? My mechanic charge approx. $210+ for the part only per cylinder.

Just want to make sure I'm not being overcharged if this part can be had for $50 or so elsewhere.

[Hillbilly]

I would do a compression test as well

[Lucas_R]

I have another mechanic I'll get to take a second look. Do you guys have any idea roughly how much each coil cost? My mechanic charge approx. $210+ for the part only per cylinder.

Just want to make sure I'm not being overcharged if this part can be had for $50 or so elsewhere.

Whoops sorry disregard.

[gonsped]

I brought in my vehicle to another mechanic 2 weeks ago - Automotive Satisfaction in Helensvale. They won mechanic of the year in GC for 2 years a few years ago. Tristan immediately diagnosed the issue, replace the entire 4x leads (not coils) and a new set of Iridium spark plugs. I gave him a copy of the (unpriced) items that was done by my previous mechanic and he even said one of the leads look second hand.

Up until now - NOTHING - no more issues. Engine smooth as, not a single glitch.

Looks like I found a new mechanic. Great price and no fuss.

[Lucas_R]

I brought in my vehicle to another mechanic 2 weeks ago - Automotive Satisfaction in Helensvale. They won mechanic of the year in GC for 2 years a few years ago. Tristan immediately diagnosed the issue, replace the entire 4x leads (not coils) and a new set of Iridium spark plugs. I gave him a copy of the (unpriced) items that was done by my previous mechanic and he even said one of the leads look second hand.

Up until now - NOTHING - no more issues. Engine smooth as, not a single glitch.

Looks like I found a new mechanic. Great price and no fuss.

Great news mate - happy motoring.