Okay, looking for little advice after an under-boost and misfire issue.

It’s a 2.0 TFSi (2007) Octavia and was recently remapped (by a well known tuner).

After giving it a hard run a few days after the remap the “Control system for exhaust gases†light started flashing. It disappeared after 15-seconds and the car behaved as normal (no limp mode). After another run, the warning light flashed again but after 15-seconds stayed on constant.

By giving it full throttle in fifth gear at 4000 RPM, I found the power would cut-off, then come back with a bit of a surge (felt like a misfire), followed by the flashing exhaust gasses warning light coming back. Obviously with all the signs of unburnt fuel entering the exhaust, I didn’t want to keep doing this!

Mute on here helped with checking out the faults with his VCDS (thanks again) which revealed the following:

000665 - Boost Pressure Regulation: Control Range Not Reached

P0299 - 002 - Lower Limit Exceeded

Freeze Frame:

Fault Status: 01100010

Fault Priority: 2

Fault Frequency: 12

Mileage: 64764 km

Time Indication: 0

Date: 2000.00.00

Time: 22:04:28

Freeze Frame:

RPM: 4365 /min

Load: 79.2 %

Speed: 87.0 km/h

Temperature: 88.0°C

Temperature: 19.0°C

Absolute Pres.: 1010.0 mbar

Voltage: 14.478 V

000768 - Random/Multiple Cylinder Misfire Detected

P0300 - 001 - Upper Limit Exceeded - Intermittent - MIL ON

Freeze Frame:

Fault Status: 10100001

Fault Priority: 2

Fault Frequency: 4

Mileage: 64804 km

Time Indication: 0

Date: 2000.00.00

Time: 17:55:05

Freeze Frame:

RPM: 4533 /min

Load: 100.0 %

Speed: 65.0 km/h

Temperature: 90.0°C

Temperature: 32.0°C

Absolute Pres.: 1010.0 mbar

Voltage: 14.224 V

000772 - Cylinder 4: Misfire Detected

P0304 - 001 - Upper Limit Exceeded - Intermittent - MIL ON

Freeze Frame:

Fault Status: 10100001

Fault Priority: 2

Fault Frequency: 4

Mileage: 64804 km

Time Indication: 0

Date: 2000.00.00

Time: 17:55:05

Freeze Frame:

RPM: 4533 /min

Load: 100.0 %

Speed: 65.0 km/h

Temperature: 90.0°C

Temperature: 32.0°C

Absolute Pres.: 1010.0 mbar

Voltage: 14.224 V

Since then, the standard map has been reinstated.

I tried to recreate the warning light under the standard map by giving the car what can only be described as a damned good thrashing! It took everything thrown at it, no misfires and no warning lights.

I described the issues to the dealer but they weren’t able to find anything wrong. Unfortunately the fault codes were cleared when reverting back to the standard map (which didn’t help them).

So…from my research on the Ross-Tech wiki, on here and other forums discussing the 2.0TFSi, the fault could be caused by one or more these possibilities…

1) Faulty OEM diverter valve (it’s a 2007 MY, but not sure which revision is fitted). Is it worth getting the ‘D’ revision fitted as a matter of course?

2) Faulty coil pack(s) and or spark plug(s) (the fault codes points towards cylinder four being the problematic area).

3) An over-tuned remap asking too much of the otherwise fully stock components (although the company that done it are well experienced with VAG tuning).

I’ve heard of similar problems being linked to pipes hanging off the N249 boost control valve, but visual checks show no problems there.

I’m sure others will have come across this before, so just wanted a general consensus of what’s most likely to be the cause?

Many thanks,

Ross

I'd have to go for coilpack 4 / or plugs..

Maybe diverter valve, but the boost pressure fault could be due to it not making boost when misfiring..

Kev

Thanks Kev!

Coilpack 4 would seem to make sense given all the other symptoms. I'm confused as to why its only happening when the tuned map is in place though.

Having said that, I have noticed a very slight judder when idling sometimes, typically when the engine is hot.

Now for the 'silly' question...

When I look in to the engine bay at my four coil packs, am I correct in saying these are numbered 1 to 4 from left to right (i.e. coil pack and cylinder four are on the far right)?

Ross, yes they are aligned in that way. 1-2-3-4 as you look at them.

Definitely sounds like a coilpack issue to me aswell.

Quick update on this issue...

While on standard map, no reoccurance of the misfire. The dealer checked twice but they couldn't spot anything wrong either.

As soon as remap was reapplied this evening, I gave it a little push and the misfire was back! Could recreate it at will.

Swapped out coil pack 4 for a new shiny one this evening and gave it some more testing...

Problem solved!

Entirely smooth throughout the range.

Thanks again to Kev & Harry for the feedback.

I don't understand enough about coilpacks to understand why one would fail with a performance map, but be perfectly okay with the stock map...even when pushed to the limits, but hey - sorted now!

I'm fitting the Rev D Diverter Valve tomorrow as a precaution to the boost fault, plus I noticed a fair bit of whistling tonight while pushing it a bit.